European Masters
in Interactive Multimedia Projects


Organisés à Bruxelles par l’Institut Supérieur de Commerce Saint-Louis

et l’Institut Supérieur de Formation Sociale et de Communication

 avec le soutien du

Programme LEONARDO da VINCI de la Commission européenne






Open Technologies for an Open World

Open Standards, Open Source, Open Mind





© 2003 Jean Binder







Document version : 1.2 - Revision: 25/05/2003


Table of Contents


Foreword_ vi

1.     Introduction_ 1

1.1.      Structure_ 1

1.2.      Open_ 3

1.3.      The Open Model_ 3

1.3.1.       Open Source 3

1.3.2.       The Open Standards 6

Part I – Open Technologies_ 9

2.     Open Infrastructure_ 10

2.1.      Hardware_ 10

2.1.1.       Traditional Server Families 10

2.1.2.       Servers – The new generation_ 13

2.1.3.       Autonomic grid on demand_ 14

2.1.4.       Clients 15

2.2.      Operating Systems_ 17

2.2.1.       z/VM and z/OS_ 17

2.2.2.       UNIX®_ 20

2.2.3.       Linux_ 24

2.2.4.       Windows 28

2.2.5.       Other Operating Systems 32

2.2.6.       Classification_ 33

2.3.      Communication_ 35

2.3.1.       Network_ 35

2.3.2.       Addressing_ 36

2.3.3.       The Internet 38

2.3.4.       Trend: Open Spectrum_ 39

2.4.      Open Trends_ 39

3.     Open Internet Development_ 43

3.1.      Design_ 43

3.1.1.       MDA_ 43

3.1.2.       CORBA_ 46

3.1.3.       UML_ 48

3.2.      Web Platforms_ 52

3.2.1.       Java_ 52

3.2.2.       .NET_ 57

3.2.3.       Java.NET_ 61

3.2.4.       The outsiders: LAMP_ 61

3.3.      Web Services_ 63

3.4.      Agile Development_ 66

3.5.      Extreme Programming_ 66

3.5.1.       Extreme Programming and Open Source 66

3.6.      Open decision_ 68

4.     Common structures for data exchange_ 70

4.1.      Content_ 70

4.1.1.       Character Codes 70

4.1.2.       Multimedia_ 71

4.1.3.       Formats for the Document Interchange 71

4.2.      XML_ 72

4.2.1.       Introduction_ 72

4.2.2.       Technical Strengths 73

4.2.3.       Openness 73

4.2.4.       XML components 74

4.2.5.       Industry Applications 74

4.3.      Trends_ 75

Part II – Brave Open World_ 76

5.     The Network Society_ 77

5.1.      Networks_ 77

5.2.      The Network Enterprise_ 78

5.2.1.       From merchant networks 78

5.2.2.       To the merchantable network_ 78

5.3.      Peer-to-peer and collective conscience_ 78

5.3.1.       Online communities 79

5.3.2.       Peer networks and cooperative computing_ 80

5.3.3.       May the force be with the hackers 80

5.3.4.       The motivated and ethical hacker 80

5.3.5.       May the force be with the hackers 81

5.3.6.       Lingua Franca_ 81

5.4.      Privacy_ 81

6.     The New Economy_ 83

6.1.      Standard wars_ 83

6.2.      Network externalities_ 84

6.3.      Feedback_ 84

6.3.1.       Positive 85

6.3.2.       Negative 87

6.3.3.       The role of the standards 88

6.4.      Cost Analysis_ 88

6.4.1.       Production Costs 88

6.4.2.       Reproduction Costs 88

6.4.3.       Distribution Costs 89

6.4.4.       Transaction Costs 89

6.4.5.       Changing costs 89

6.4.6.       TCO_ 90

6.4.7.       Cost comparison_ 91

6.4.8.       ROI - The conclusion is beyond the costs 92

6.4.9.       Case studies – cost reduction_ 93

6.5.      Evolution and Control: Two flavours, four strategies_ 94

6.5.1.       Openness or Control 94

6.5.2.       Performance or Compatibility 96

6.5.3.       The strategies 96

6.6.      The shift of power_ 97

6.6.1.       Behind the marketing scenes 98

6.6.2.       The experience economy 98

6.6.3.       Branding_ 99

7.     Politics_ 100

7.1.      Openness by research_ 100

7.2.      Openness by usage_ 100

7.3.      Openness by law enforcement_ 101

7.4.      Openness by stimulation_ 102

Part III – CODA_ 103

8.     Open Future_ 104

8.1.      INCA_ 105

Part IV – Annexes_ 106

Appendix A.       The Open book_ 107

Appendix B.       Standards Organizations_ 108

Appendix C.       References_ 110

C.1.     Trademarks_ 110

C.2.     Figures_ 110

C.3.     Tables_ 111

Appendix D.       Bibliography_ 112





·                 Motivations

“Sometimes dreams are all that separate us from the machines” – Dan Simmons in The Fall of Hyperion


“Sometimes (…) the shortest route to courage is absolute ignorance” – Dan Simmons in Endymion



Recently we have heard a lot about Linux. Several discussions have been held in the professional circles, and the media is getting the message to the general public. It can be considered the major open source product, and the responsible for this public awareness. However, the concepts behind open source must also be explained, and - beyond this - the existence of open standards and protocols shall be understood. The comparison between “open” and proprietary software should not be limited to the cost, neither be influenced by the impression that open means free. What is the importance of this understanding for multimedia project managers?


There is a general theory about the transparency of the computer infrastructure for the Internet and intranet implementations, in phases like design, project management and decision-making. During this document, I aim to prove the importance of a general understanding of the hardware, software and communication infrastructure, to improve the overall quality of the project and the decision making process. The first battle between open and proprietary solutions will take place in the technological field. And this is only the beginning of the war.


The knowledge acquired when studying the impact of standards and open source for the Internet infrastructure, may be used to understand the consequences in other levels, like the design, the development and the exchange of structured information. Intensive research has been performed in the last decade, now the solutions are ready to be deployed. It’s time to participate in the dialogs, discussion and analysis, which will make the standards for the future. It’s essential to understand the social and economical rationales behind open and proprietary solutions, and how the political world can help to build a technological future.


This is an ambitious though, I agree. Nevertheless, the ongoing social movements using the peer-to-peer concept are showing the power of tightly coupled motivated persons. Linux is there to prove it.


·                 Sources


I tried to be eclectic, using some books and syllabi as basic references for the technological, economical and social analysis, my 2-year collection of Datanews magazines to analyse the current evolutions of the Belgian and European market and political environment, seminars and the Internet to complete the evaluation from a global and updated standpoint. These are always fully referenced in the footnotes, with complete details being given in the Appendix D.





·                 Method


There are many different technological aspects discussed in this document. At a first sight, it may look like a collection of superficial investigations about different topics. However, it aims to discuss open solutions in a very broad scope. So I studied every information technology aspect, which is at the same time important to the development of multimedia applications and currently with interesting questions about the choice of open or proprietary alternatives. A brief explanation about the technology itself is always given in the beginning of each chapter and paragraph, to allow the reading of this document without pre-requisites. The focus of the discussion is always around open source and open standards. To allow this document to be read in modules or in non-sequential browsing, the conclusions are often done in the end of each chapter and paragraphs.


·                 The light side of the moon


There are two ways of reading this thesis. The shortest and funny way is to go directly to the online conclusion (, play around with the suggested architecture for the future, and then come back to the document and read only the topics that really interest and attract you. Then disagree with my standpoint and tell me why (by using the website to exchange opinions, the readers can have an open discussion around the topics discussed in this document, which can be a basis for the effective design of the new architecture).


The second way is to continue reading this document.


·                 Acknowledgements


Many thanks to my wife Joyce for the strong support during the long research evenings, nights and weekends. Big thanks to my sister Mariana who helped me to keep concentrated to finish this work. The open spirit of my daughter and family, from the cradle, were also fundamental for my motivations.


Special regards to the Professor Jean-Luc Vidick for the help to structure this document in its final form, and to complete it with important topics about the extreme development; to the professor Michel Bauwens for the interesting discussions that helped me to find the target subjects and to compose the bibliography; to the professor Attila Darabos for the final revision; and to the professor Pierre Rummens for the remarks about the research methods and the document formats and structures.


I hope you enjoy the reading, and if you feel motivated by my ideas please feel free to help me improving this document[1].



1.   Introduction


1.1.        Structure

“Let’s say there are four steps. Four stages. Four levels. The first Is learning  the language of the dead, the second is to learn the language of the living, the third is hearing the music of the spheres. The fourth step is learning to take the first step.” – Dan Simmons in The Fall of Hyperion


The standardization is an important point to be considered in the evolution of the different technologies, and so is their openness. It gives developers the possibility to understand the infrastructure requirements, to create compatible products, to participate in their evolution, to innovate. This openness may be well represented in the source code, the “alma mater” of every computer program. We need to understand “Open Source” as the concept created by computer programmers united under the hackers ethic. However, we should not be limited by it: We shall go one abstraction level further to define the “Open” concept, by analysing also the Open Systems, the Open Standards and the Open Platforms. The first part of the analysis will be divided into three different tiers, which compose together the realm of IT and Internet today. They are the infrastructure, the development and the information exchange (see figure below).





























Figure 1 – The three tiers under the scope of the first part of this analysis


Let’s start by the bottom-level tier, and discuss in the first chapter the hardware and the operating systems used to build the Internet infrastructure. Different alternatives are investigated, trying to understand their original goals, their evolution, their current situation and the tendencies. The analysis is always focused on the applicability of the platforms as servers taking part on the Internet infrastructure. And what is the base of Internet? The standards. They participated in the spread of the Net from the very beginning, so they do in this document. The goal is to understand what are the different hardware platforms, the software environments, their concepts, history and targets, and how they became standards. We will also analyse what benefits we may expect from the open environments, together with the level of openness available from the common proprietary alternatives. We conclude with the role of standards on the creation of network protocols used worldwide, tantamount for the success of Internet.


In the second tier - development - we can consider the ongoing battle for a common web platform and the role of the web services. This is excellent for a case study, as we have three different warriors: An open source, an open platform, and a proprietary solution. Additionally we will analyse the usage of common rules to exchange information about the design of applications and data, with the goal of technology independence: MDA and UML. We briefly discuss the extreme programming concepts and their relation with the open source products and projects.


The analysis ends with the third tier – information exchange - by exploiting the benefits of a common language to exchange information and data definitions, coupled and structured. This is done by XML and its derivates.


The aim of the second part is to analyse the technologies by a broader standpoint. We should be able to trace some conclusions and imagine future trends and proposals. Using the cases detailed in the first part, we will analyse some of the basic concepts around the network society and the new economy, trying to understand the impact of standards in the usage of technological power, the strategies currently used by the enterprises, the comparative elements between open and proprietary solutions. Finally, we will discuss the role of politics, to enforce or stimulate the usage of open technology.


This study contains background material that introduces some important topics for readers who are not familiar with them. References are provided for those who want more complete understanding. The hyperlinks fans should refer to the Appendix A, on page 107, and feel free to use the online version on, which intend to be often up-to-date. As an avant-goût, the basic concepts used during the rest of the document.


1.2.        Open


To define the Open general concept, under the scope of this study, let us consider two definitions, with the help from the dictionary[2]:



1: having no enclosing or confining barrier: accessible on all or nearly all sides

5: not restricted to a particular group or category of participants


Based on this, we can consider as “Open” any product, concept, idea or standard:


§         That is freely available to be researched, investigated, analysed and used with respect to the intellectual property;


§         That can be adapted, completed and updated by any person or company interested in improving its quality or the functionality, possibly coordinated by a person or organization.


Let us now analyse the open model, used for Open source development and the establishment of open standards.


1.3.        The Open Model


1.3.1.         Open Source


·                 Definition


Historically, the makers of proprietary software have generally not made source code available. Defined as “any program whose source code is made available for use or modification as users or other developers see fit” [3], open source software is usually developed as a public collaboration and made freely available.


Open Source is a certification mark owned by the Open Source Initiative (OSI). Developers of open software (software intended to be freely shared, potentially improved and redistributed by others) can use the Open Source trademark if their distribution terms conform to the OSI's Open Source Definition[4]. All the terms below must be applied together, for the product and its license, and in all cases:


§         Free Redistribution – The software being distributed must be redistributed to anyone else without any restriction.










As Perens summarizes, from the programmer’s standpoint, these are the rights when using Open Source programs:


§         The right to make copies of the program, and distribute those copies.





·                 Licenses


There are many different types of licenses used by Open Source products. The most common are[6]:


§         Public Domain – A public-domain program is one upon which the author has deliberately surrendered his copyright rights. It can’t really be said to come with a license. A public domain program can even be re-licensed, its version removed from public domain, with the author name being replaced by any other name.


§         GPL (GNU General Public License) – the GPL is a political manifesto as well as a software license, and much of its text is concerned with explaining the rationale behind the license. GPL satisfies the Open Source Definition. However, GPL does not guarantee the integrity of the author’s source code, forces the modifications to be distributed under the GPL and does not allow the incorporation of a GPL program into a proprietary program.


§         LGPL (GNU Library General Public License) – The LGPL is a derivative of the GPL that was designed for software libraries. Unlike the GPL, a LGPL program can be incorporated into a proprietary program.


§         X, BSD and Apache – These licenses let you do nearly anything with the software licensed under them. This is because their origin was to cover software funded by monetary grants of the US government.


§         NPL (Netscape Public License) – This license has been prepared to give Netscape the privilege of re-licensing modifications made to their software. They can take those modifications private, improve them, and refuse to give the result to anybody (including the authors of the modifications).


§         MPL (Mozilla Public License) – The MPL is similar to the NPL, but does not contain the clause that allows Netscape to re-license the modifications.



Can be mixed with non-free software

Modifications can be taken private and not returned to their authors

Can be re-licensed by anyone

Contains special privileges for the original copyright holder over the modifications

Public Domain






























Table 1 – Comparison of Open Source licensing practices[7]


·                 Open Source software engineering


The traditional software engineering process generally consists of marketing requirements, system-level design, detailed design, implementation, integration, field-testing, documentation and support. An Open Source project can include every single one of these elements:


§         The marketing requirements are normally discussed by using a mailing list or newsgroup, where the needs from one member of the community are reviewed and complemented by the peers. Failure to obtain consensus results in “code splits”, where other developers start releasing their own versions.


§         There is usually no system-level design for a hacker-initiated Open Source development. A basic design allows the first release of code to be built, and then revisions are made by the community. After some versions, the system design is implicitly defined, and sometimes it is written down in the documentation.


§         Detailed design is normally absent of pure open source initiatives, mostly because most of the community is able to read the code directly, interpret the routines, functions and parameters, and modifying them as required. This makes further development more difficult and time-consuming.


§         Implementation is the primary motivation for almost all Open Source software development effort ever expended. It is how most programmers experiment with new styles, ideas and techniques.


§         Integration usually involves organizing the programs, libraries and instructions in such a way they can be used by users in other systems and equipments to effectively use the software.


§         Field-testing is one of the major strengths of Open Source development. When the marketing phase has been effective, many potential users are waiting for the first versions to be available, and willing to install them, test and make suggestions and correct bugs.


§         The documentation is usually written in a very informal language, free style and usually funny way. Often websites are created to allow the documentation to be provided and completed by the user community, and becomes a potential source for examples, “tips and tricks”. One of the brightest examples is the online documentation for PHP[8].


§         The support is normally provided via FAQS and discussion lists or even by the developers themselves by e-mail, in a “best effort” basis, depending on their availability, willingness and ability to answer the question or correct the problem. The lack of official support can keep some users (and many companies) away from Open Source programs, but it also creates opportunities for consultants or software distributors to sell support contracts and/or enhanced commercial versions.


The commercial versions of Open Source software (like BSD, BIND and Sendmail) often use the original Open Source code, developed using the hackers model, later refined by most of the phases described above.



·                 Open-source cycle


Many Open Source software start with an idea, discussed via the Internet, developed by the community, implemented as first draft versions, and consolidated into final versions after a lot of debugging. After this final software starts to be used globally, and interesting companies, the authors may decide to start receiving some financial compensation for their hard work.


Then an organization may be created, or some existing company can start to distribute the product alone or bundled with other similar pieces of software. Sometimes, after a reasonable funding is raised and more development is done (now remunerated) a commercial version of the product may be released, often with more functionality than the free version, and sometimes without the source code being generally distributed. This is attributed to the difficulty of small companies to remain profitable by distributing only open source software.



·                 Open Source Science


As argued by DiBona, Ockman and Stone[9], “Science is ultimately an Open Source enterprise. The scientific method rests on a process of discovery, and a process of justification. For scientific results to be justified, they must be replicable. Replication is not possible unless the source is shared: the hypothesis, the test conditions, and the results. The process of discovery can follow many paths, and at times scientific discoveries do occur in isolation. But ultimately the process of discovery must be served by sharing information: enabling other scientists to go forward where one cannot; pollinating the ideas of others so that something new may grow that otherwise would not have been born.”


Ultimately, the Open Source movement is an extension of the scientific method, because at the heart of the computer industry is computer science. Computer science differs from all other sciences, by having one means of enabling peers to replicate results: share the source code. To demonstrate the validity of a program, the means to compile and run the program must be provided.


Himanen considers that the scientists have developed this method “not only for ethical reasons but also because it has proved to be the most successful way of creating scientific knowledge. All of our understanding of nature is based on this academic or scientific model. The reason why the original hackers Open Source model works so effectively seems to be – in addition to the facts that they are realizing their passions and are motivated by peer recognition, as scientists are also – that to a great degree it confirms to the ideal open academic model, which is historically the best adapted for information creation”[10].


1.3.2.         The Open Standards


One of the important factors in the success of the Internet comes from the "governance mechanisms" (rather than regulation) that guide its use and evolution, in particular, the direct focus on inter-connection and interoperability among the various constituent networks.




·                 Standards 


The standards are fundamental for the network economy. They allow the companies to be connected by establishing clear communication rules and protocols. For manufacturing networks, composed by the company with the product design, the suppliers of different components and the assembly lines, standards guarantee the compatibility of all the different parts in the production process. In the information and technology networks, the standards guarantee the compatibility of the infrastructure components analysed in the first chapter – hardware, operating systems and application software – and the interoperability of the companies via the Internet with clear network protocols.


Standardization is by definition a political, economical and technological process aiming to establish a set of rules. These are documented agreements containing technical specifications or other precise criteria to be used as rules, directions or definitions. Thus, equipments, products, processes and services based in the same set of rules are fully compatible with each other.


·                 De facto or De jure


Standards are normally classified according to their nature. De facto standards are products and protocols which conquer the market by establishing a network of interconnected and compatible products, and gaining recognition from the consumers. An example is the set of de facto standards built around the IBM PC specification.























Figure 2 – Examples of de facto standards and their connectivity


De facto standards are normally preferred by companies because they don’t need to follow a complex and time-lengthy process for its validation. Often – as the case of Windows – they are accepted by the market even without being elaborated by scientific process, and without strong R&D investments. These are also the reasons by which they are not easily accepted by normalisation organisations, by the scientific institutions and by the academic circle.


By opposition, de jure standards are often based on a new technology, created by a company that accept to publish their concepts and definitions for a review of the academic and scientific communities, and be officially approved by a normalisation institution. A good example is the OSI standard and the protocols compatible with its different tiers (see the Figure 14 on page 35).


Some of the main motivations for this are the ability to compete with existing dominant standards, to easily found a cooperation network of software and hardware suppliers, to obtain credibility from the academic world and consequently gathering the cooperation from the students community.


A good practice from the really independent and non-profit normalisation organisations is to only accept to recognise open standards. This is necessary to avoid the formation of monopolies and unfair commercial practices by the royalty-owners. This has recently been contested when standards for web services have been analysed.


De facto standards

De jure standards


-         Quickly developed

-         Optimal solution for the original goal


-         Lengthy development

-         Solution can be used beyond the original goal

-         Compromise of technical choices


-         Short-sighted

-         Not clearly defined

-         Stimulates monopolies (by copyrights)

-         Multiple solutions for the same type of applications


-         Long term analysis by experts

-         Clear and complete definitions

-         Stimulates competition

-         Standard controlled by independent organizations rather than companies

-         Possibility of independent certifications

Table 2 – Comparison between de facto and de juri standards[11]


·                 Mare liberum or Mare clausum


One standard is known as proprietary when it has been developed by a company, which remains the owner of royalties that limit the usage of the standard specifications by the payment of licence fees.


Open Standards are standards with specifications which are open to the public and can be freely implemented by any developer. Open standards usually develop and are maintained by formal bodies and/or communities of interested parties, such as the Free Software/Open Source community. Open standards exist in opposition to proprietary standards, which are developed and maintained by commercial companies. Open standards work to ensure that the widest possible group of contemporary readers may access a publication. In a world of multiple hardware and software platforms, it is virtually impossible to guarantee that a given electronic publication will retain its intended look and feel for all viewers, but open standards at least increase the likelihood that a publication can be opened in some form.


From a business perspective, open standards help to ensure that product development and debugging occurs quickly, cheaply and effectively by dispersing these tasks among wide groups of users. Open standards also work to promote customer loyalty, because the use of open standards suggests that a company trusts its clients and is willing to engage in honest conversations with them. Criteria for open standard products include: absence of specificity to a particular vendor, wide distribution of standards, and easy and free or low-cost accessibility.



·                 Protocols


A protocol is the special set of rules used by different network layers, allowing them to exchange information and work cohesively. In a point-to-point connection, there are protocols between each of the several layers and each corresponding layer at the other end of a communication.[12]


The TCP/IP protocols (TCP, IP, HTTP…) are now quite old and probably much less efficient than newer approaches to high-speed date networking (e.g. Frame Relay or SMDS). Their success stems from the fact that the Internet is often today the only possible outlet that offers a standardized and stable interface, along with a deliberate focus on openness and interconnection. This makes the Internet extremely attractive for very different groups of users, ranging from corporations to academic institutions. By contrast with traditional telecommunications networks, the rules governing the Internet focus on interconnection and interoperability, rather than attempting to closely define the types of applications that are allowed or the rate of return permitted to its constituents.[13]


·                 Architectures or Platforms


Architecture is a term applied to both the process and the outcome of thinking out and specifying the overall structure, logical components, and the logical interrelationships of a computer, its operating system, a network, or other conception. Architectures can be specific (e.g. IBM 360, Intel Pentium) or reference models (e.g. OSI). Computer architectures can be divided into five fundamental components (or subsystems): processing, control, storage, input/output, and communication. Each of them may have a design that has to fit into the overall architecture, and sometimes constitute an independent architecture[14].


As it will be exploited in the chapter 2.2.1 (z/VM and z/OS), the usage of open architectures – even when maintained by commercial companies - can bring many technical advantages to the suppliers of the building blocks (Software, hardware and network components) and mainly to the user community, which can profit from a large network of compatible components, ensuring an independence and favouring concurrence, creativity and innovation. The economic potential will be analysed in details on the chapter 6.3 (Feedback).


The term platform may be used as a synonym for architecture, and sometimes may be used to designate their practical implementations.


·                 Certification


Certify is to validate that products, materials, services, systems or persons are compliant to the standard specifications. One chapter of the standard definitions is always dedicated to the certification steps to be performed, and the specifications to be verified.


The certification process may be performed by any entity. However, independent organizations are normally responsible for the certification process, which may be expensive and require specialized technological knowledge.[15]


Part I – Open Technologies

“It’s the question that drives us. The question that brought you here. You know the question,

 just as I did.” Trinity in The Matrix






2.   Open Infrastructure


“Technology is neither good nor bad, nor is it neutral” – Melvin Kranzberg


According to Patrick Gerland, “the three essentials of computer technology are: hardware - the physical machinery that stores and processes information -, software - the programs and procedures that orchestrate and control the operation of hardware - and people who know what the hardware and software can do and who accordingly design and implement applications that exert appropriate commands and controls over hardware and software to achieve desired results”.[16]


Despite the broad discussion about open source and its influence on the evolution of hardware and software, there’s a general lack of knowledge about the different types of operating systems, their original and current targets, and their relationship with the hardware platforms and architectures. For a better understanding of the further topics, let’s start by discussing this infrastructure and analyse the status of the hardware and basic software. This analysis will also solidify the definition of architecture, standards and protocols, to be used on the following chapters. We will see, for example, that new concepts as Open Source and ASP are largely inspired in their parents Open Systems and Time Sharing.


The hardware and software components are sometimes generically referred to as middleware.


2.1.        Hardware


Hardware is a broad term. It covers all the equipment used to process information electronically, and it’s traditionally divided into two main categories: computers and peripherals[17]. In this section, we will concentrate our analysis in the evolution of the computers, from owned machines into commodities. Peripheral references to the peripherals will be done. Let us consider the division of the computer into servers and clients, discuss the traditional server families, and the new concept of servers. After, we will briefly analyse the machines in the client-side.


2.1.1.         Traditional Server Families


In the beginning, they were simply called computers. And they were large-scale computers. In the mid-1980’s, after the surge of the personal computers, we started to classify the computers according to their capacity, their price, their “original” goal and their target users. This classification remained until the end of the 1990s, and the three different families will now be briefly described.




·                 Mainframes


Let’s not talk about the big computers filling entire rooms, weighting tons and composed by valves[18]. This is not a mainframe any more, for a long time. Let’s think about relatively small servers (they are often not larger than a fridge) with big power capacity, enough to run online applications for thousands of users spread over different countries, and to process batch jobs which can process millions of nightly database updates. They have never been sexy (and this was not the goal: we are talking about a period between 1970 and 1985, when graphics, colours, sound and animation were not part of the requirements for a professional computer application) and today it seems that the only alternative for them to survive is to mimic and co-operate with open systems environments.


Usually mainframe applications are referred to as “legacy” (“Something received from the past[19]”). One can argue the usage of this term[20], mainly because of the undeniable stability and performance of these machines and considering that most of the core applications for big companies are still processed using mainframe computers, connected with computers from other platforms to get profit from a better user interface.


Current mainframe brands are IBM zSeries, Hitachi M-Series, Fujitsu-Siemens PrimePower 2000 and BS2000 and Ahmdal Millenium[21]. The term mainframe is also being marketed by some vendors to designate high-end servers, which are a direct evolution from the mid-range servers, with a processing capacity (and price) aiming to compete with the traditional mainframes.

Figure 3 – IBM ZSeries 900


·                 Mid-range servers


This is a difficult assumption to make. The capacity of the machines in this category is increasing fast, and they are already claiming to be high-end servers, and winning market share from the mainframes. Let’s consider it a separate category, for the moment.


Once upon a time, there were the minicomputers[22]. They used to fill the mid-range area between micros and mainframes. As of 2001, the term minicomputer is no longer used for the mid-range computer systems, and most are now referred to simply as servers[23]. Mid-range servers are machines able to perform complex processing, with distributed databases, multi-processing and multi-tasking, and deliver service to the same number of users than a high-end server, but with lower cost and often with an inferior level of protection, stability and security.

The main suppliers in this area are HP and Sun.





Figure 4 – HP RISC rp8400


·                 Low-range servers


Initially the microcomputers were used as desktop, single-user machines. Then they started to assume functions from the minicomputers, like multi-tasking and multi-processing. Nowadays they can provide services to several users, host web applications, function as e-mail and database servers. Initially each server was used for a different function, and they were connected via the network. This is called multi-tier server architecture. With the evolution of the processing speed, today each server  may be used for several functions.

They may also work as metaframes, providing service to users connected via client or network computers. All the applications run in the server side (that is required to have a very good processing capacity), which exchange the screens with the clients (that can be relatively slow).


There are several suppliers in this area, like Dell and Compaq.

Figure 5 – DELL Poweredge 1600SC
















Figure 6 – Traditional Server families[24]


2.1.2.         Servers – The new generation


The classification categories discussed before are becoming more difficult to define and the division lines are blurring. The new generation of servers span a large range of price and processing capacity, starting by low-entry models, until powerful high-end servers, which can be tightly connected into clusters. This methodology is implemented – in different ways – by the most part of the hardware suppliers in the server market.



















Figure 7 – The new generation of servers


The differences between the entry-level and high-end servers depend on the architecture and the supplier. They may imply the number of parallel processors, the type and capacity of each processor, the memory available, cache, and connections with the peripherals. The clusters are normally used for applications demanding intensive calculations, and are composed by several servers connected by the usage of high-speed channels (when they are situated in the same space) or high-speed network links (when the servers are geographically dispersed to provide high availability in cases of natural disasters). There are many different ways to implement the clusters to obtain a single point of control and maintenance, treating the cluster almost as a single server – without creating a single point of failure, which could imply the complete unavailability of the cluster in case of problems with one of the elements.


Estimate the throughput for future applications is only possible with a good capacity planning, prepared by experimented specialists. To find a server – as performance tests with the real charge are quite difficult to be elaborated - there are several benchmarks, organized by recognized independent companies, each one with a clear advantage for a different supplier. As the cost is extremely important - and when the hardware supplier participates in the capacity planning – a Service Level Agreement (SLA) may specify guarantees that the capacity installed will satisfy the estimated demand.


However, another differentiating factor, which is gaining importance nowadays, is the openness of the hardware and operating systems. This will be largely exploited further in this document.


2.1.3.         Autonomic grid on demand


The current challenge, in the quest for the holy server, is to build flexible, scalable and resilient infrastructures, able to respond to unexpected surges in traffic and use. The solution may be found by implementing concepts like grid computing and autonomic computing, which are highly dependent on open standards and tightly related to open source.


·                 Grid Computing


Grid computing[25] is a new, service-oriented architecture that embraces heterogeneous systems and involves yoking together many cheap low-power computers - dispersed geographically - via open standards, to create a system with the high processing power typical of a large supercomputer, at a fraction of the price. The goal is to link – mainly through the Internet – computers and peripherals, by cumulating their processing and stocking capacities. All the connected systems may then profit from the set of assembled resources – like processing capacity, memory, disk, tapes, software and data – that are global and virtual at the same time.[26]


The challenges are to connect different machines and standards, to develop software able to manage and distribute the resources over the network, to create a development platform enabling programs to make profit of the parallel and distributed tasks, security issues (authentication, authorisation and policies) and to develop reliable and fast networks.


The basic principle is not new, as the HPC (high performance computing) technology is already used in academic and research settings, and the peer-to-peer has already been used to create a large network of personal computers (e.g. SETI@home). The target now is to expand this technology to the business area via associations like the Global Grid Forum (assembling more than 200 universities, laboratories and private companies).


Another initiative is the Globus project, formed by many American research institutes, responsible for Globus toolkit, which uses Open Source concepts for the basic software development, and has created the Open Grid Services Architecture (OGSA), a set of open and published specifications and standards for grid computing (including SOAP, WSDL and XML). The OGSA version 1.0 has been approved in December 2002. Other similar projects are Utility Computing (HP) and N1 (Sun)[27].


With the costs to acquire, deploy, and maintain an expanding number of servers weighing down potential productivity gains, the market is shifting toward various concepts of service-centric computing. This may hold deep potential to not only lower the capital and operational costs of a data centre, but also to impart that infrastructure with the increased availability and agility to respond to an ever-changing business environment.


·                 Autonomic Computing[28]


As IT systems become more complex and difficult to maintain, alternative technologies must manage and improve its own operation with minimal human intervention. Autonomic computing is focused in making software and hardware that are self-optimising[29], self-configuring[30], self-protecting[31] and self-healing[32]. It is similar to the grid concepts, by embracing the development of intelligent, open systems that are capable of adapting to varying circumstances and preparing resources to efficiently handle the workloads placed upon them. Autonomic computers aren’t a separate category of products. Rather, such capabilities are appearing in a growing number of systems.


The objective is to help companies more easily and cost-effectively manage their grid computing systems. It’s expected that when autonomic computing reaches its full potential, information systems will run themselves based on set business policies and objectives. The implementation of such a system start with a trial phase, in which the system suggests actions and then wait for approval. After a fine-tuning of the rules, the system may run unattended.


It’s believed that only a holistic, standards-based approach can achieve the full benefits of autonomic computing. Several standards bodies – including the Internet Engineering Task Force, Distributed Management Task Force and Global Grid Forum – are working together with private companies to leverage existing standards and develop new standards where none exist. Existing and emerging standards relevant to autonomic computing include:


One example of current technologies using autonomic components is disk servers with predictive failure analysis and pre-emptive RAID reconstructs, which are designed to monitor the system health and to detect potential problems or systems errors before harming the data. Performance optimisation is also obtained via intelligent cache management and I/O prioritisation[33].


2.1.4.         Clients


·                 Desktops (and laptops)


In the beginning of the personal computers, hobby was the main objective, and there were several different platforms (Amiga, Commodore, TRS80, Sinclair, Apple, among others) completely incompatible. BASIC[34] was the common language, although with different implementations. Then, in 1981, IBM created the PC – the first small computer to be able to run business applications - and in 1984, Apple released the Macintosh – the first popular graphical platform. The era of microcomputers started.


The natural evolution of the microcomputers, today’s desktops are able to run powerful stand-alone applications, like word processing and multimedia production. They are normally based on Intel or Macintosh platforms and used by small businesses or home users. They are much more powerful when connected to one or more servers, via network or the Internet. They become clients, and can be used to prepare and generate requests that are processed by the servers, and then receive, format and display the results.


Most of the desktop market is dominated by computers originated from the IBM PC architecture, built from several suppliers (and even sold in individual parts) around Intel and AMD processors. Apple is also present – with a different architecture - traditionally in the publishing and multimedia productions.


















Figure 8 – Desktop x Network computers


·                 Network Computing


Recent evolutions from the desktops, the Network Computers (also called WebPC or NetPC) are also used as clients, with less power and more flexibility. Normally these computers have built-in software, which is able to connect to the network and fetch the needed applications from the servers, or simply use the applications running on the servers themselves.


The main objective is to allow shops and sales persons to work from anywhere in the world in the same way, with the same profile, even if changing the hardware interface. It also allows a better level of control over personalization, as all the information is always stored in the server, the client working simply as the interface.


Main suppliers are IBM and Compaq, with network computers working as PC clients, and Citrix with a proprietary client able to connect only to Citrix servers and obtain a perfect image of PC client applications via the network. Similar technology can be found under the names “thin clients” and “smart display”.


To support the development of network computing, the company Sun developed a new language (Java[35]), aiming to guarantee the independence of the hardware equipment or platform by the usage of Virtual Machines[36].



·                 Pervasive Computing


The idea is to connected small devices than laptops to the network. The PDAs are largely used today, and have the capacity to work in network, even if the communication costs avoid many to use them to send e-mails and to connect to the Internet.


With the decreasing size of the chips, and with the development of wireless protocols – like bluetooth and WiFi - some technology “hype-makers” are trying to convince the general public that they need every single appliance connected to the network. Although with some interesting applications, most of them are simply gadgets. With the current economic crisis, there is a low probability that such products will have a viable commercialisation soon.


Some companies are using these technologies in warehouse management systems, to reduce costs and increase the control on stock and product tracing. Also current is the usage of Linux in set-top boxes, able to select TV channels, save programs in hard disks for later viewing, filter channel viewings according to license keys.


See also chapter 2.3.4 (Trend: Open Spectrum).

2.2.        Operating Systems


As we already discussed, hardware is the equipment used to process information. An Operating System is the system software responsible to manage the hardware resources (memory, Input/Output operations, processors and peripherals), and to create an interface between these resources and the operator or end-user[37].


Originally, each hardware platform could run its own operating system family. This is not true any more. Here we are going to briefly analyse some examples of well-known operating systems, and present some historical facts related to standards, architectures and open source. Later we are going to discuss the initial dependence between the operating systems and the architecture, and how this has changed.

2.2.1.         z/VM and z/OS


With a history started in 1964, IBM mainframe operating systems are currently z/VM and z/OS (a third one, VSE/ESA[38], is only kept for compatibility issues). They share the same architecture (currently called z/Architecture[39]) and their main characteristics are:


§         z/VM[40] was originally built to ease the machine resources sharing by creating simulated computers (virtual machines), each running its own operating system[41].


§         z/OS[42] - has always been the operating system used by large IBM systems, offering a great level of availability and manageability.


·                 Architecture


IBM has been the leader of the mainframe commercial market since the very beginning, with strong investments in R&D and marketing strategies, and with a determination to use common programming languages (like COBOL) in the conquest of programmers and customers. One key factor for IBM’s success is standardization. In the 1950s, each computer system was uniquely designed to address specific applications and to fit within narrow price ranges. The lack of compatibility among these systems, with the consequent huge efforts when migrating from one computer to another, motivated IBM to define a new ”architecture” as the common base for a whole family of computers. It was known as the System/360, announced on April 1964[43], which allowed the customers to start using a low-cost version of the family, and upgrade to larger systems if their needs grew. Scalable architecture completely reshaped the industry. This architecture introduced a number of the standards for the industry - such as 8-bit bytes and the EBCDIC character set[44] - and later evolved to the S/370 (1970), 370-XA (1981), ESA/370 (1988), S/390 (1990) and z/Architecture (2000). All these architectures were backward compatible, allowing the programs to run longer with less or no adaptation, while convincing the customers to migrate to the new machines and operating systems versions to profit from new technologies.


The standardization of the hardware platforms, by using a common architecture, helped to unify the efforts from the different IBM departments and laboratories spread over the world. The usage of a common set of basic rules was also fundamental in the communication among the hardware and software departments, which allowed the existence of the three different operating system families, able to run in the same hardware.


·                 Relative Openness


This architecture is proprietary (privately owned and controlled - the control over its use, distribution, or modification is retained by IBM), but its principles and rules are well defined and available to the customers, suppliers and even the competitors[45]. This openness allowed its expansion by:





·                 The negative aspects


There’s also a dark side: several times, IBM has been accused of changing the architecture without giving enough time to the competitors to adapt their hardware and software. Only when the competition from other high-end servers suppliers increased, IBM has been forced to review this policy, creating the concept of “ServerPac”. The operating system started to be bundled with ISV software, giving the user a certain guarantee of compatibility.


A second problem is the complete ownership of the standards, by IBM. Even if other companies found good ways of implementing new technologies, thus improving the quality of the service or the performance, they always needed to adapt their findings to fit in the IBM architecture[47]. This limited the innovation coming from the OEM companies as they could rarely think about improvements that would imply architectural changes. On the other hand, the customers were never sure if the changes imposed by IBM were really needed, or simply another way of forcing them to upgrade the operating systems version or the hardware equipment with an obvious financial benefit for IBM.


A third aspect is related to the availability of the code source of the operating systems and basic software. Originally, IBM supplied the software with most part of the source code and a good technical documentation about the software’s internal structures. This gave the customers a better knowledge about the architecture and the operating systems, allowing them to analyse problems independently, to drive their understanding beyond the documentation, and to elaborate routines close to the operating systems. After, they created the “OCO” (Object Code Only) concept, which persists today. The official reason behind this was the difficulty for IBM to analyse software problems, due to the increasing number of customers that started to modify the IBM software to adapt them to local needs, or to simply correct bugs. In fact, by hiding the source code IBM also avoided that customers discovered flaws and developed interesting performance upgrades. This also helped to decrease the knowledge level from the technical staff, which is limited today to follow the instructions given by IBM, when installing and maintaining the software. The direct consequence was a lack of interest for the real system programmers and students, who have been attracted to UNIX and Open Source environments. A positive consequence of the OCO policy is the quicker migration from release to release. Since the code is not modified, but instead APIs (Application Programming Interfaces[48]) can be used to adapt the system to each customer needs.


·                 Impacts


These factors were crucial to create a phenomenon called downsizing: Several customers, unhappy with the monopoly in the large systems, and with the high prices practiced by IBM and followed by the OEM and ISV suppliers, started to migrate their centralized (also called enterprise) systems to distributed environments, by using midrange platforms like UNIX. In parallel (as it will be discussed on chapter 2.2.2), there were many developments of applications and basic software in the UNIX platforms, the most important around the Internet. To counterattack, IBM decided to enable UNIX applications to run in their mainframe platforms: MVS (the Open Edition environment, now called UNIX System Services) and VM (by running Linux as guest operating systems in virtual machines). IBM major effort today is to create easy bridges between those application environments, and to convince the customers to web-enable the old applications, instead of rewriting them.


Important is to notice that the standardisation on the hardware level was not abstracted to the operating system level. As mentioned above IBM always maintained three different operating systems, each one targeted to a different set of customers. This was not always what IBM desired, and in every implementation of a new architecture level (e.g. XA, ESA), the rumours were that the customers would be forced to migrate from VM and VSE to MVS, which would become the only supported environment. This is still true for the VSE (note that there’s no z/VSE announced yet), but z/VM became a strategic environment allowing IBM to implement Linux in all hardware platforms.


Usually, the mainframe implementations are highly standardized. As the professionals in this domain understood the need for standards, the creation of company policies is done even before installing the systems.


2.2.2.         UNIX®

"Unix was the distilled essence of operating systems, designed solely to be useful. Not to be marketable. Not to be compatible. Not to be an appendage to a particular kind of hardware. Moreover a computer running Unix was to be useful as a computer, not just a `platform' for canned `solutions'. It was to be programmable - cumulatively programmable. The actions of program builders were to be no different in kind from the actions of users; anything a user could do a program could do too...." (McIlroy - Unix on My Mind)


An analysed by Giovinazzo, “while it may seem by today’s standards that a universal operating system like UNIX was inevitable, this was not always the case. Back in that era there were a great deal of cynicism concerning the possibility of a single operating system that would be supported by all platforms. (…) Today, UNIX support is table stakes for any Independent Software Vendor (ISV) that wants to develop an enterprise class solution”[49].

It may surprise some people but the conception of UNIX (MULTICS) started almost in the same time than the IBM System/360, and the first UNIX edition was released just after the IBM System/370, in November 1971[50]. MULTICS was developed by the General Electric Company, AT&T Bell Labs[51] and the Massachusetts Institute of Technology to allow many users to access a single computer simultaneously, allowing them to share data and the processing cost. Bell Labs abandoned the project and used some of MULTICS concepts to develop UNIX on a computer called DEC PDP-7, predecessor of the VAX computers[52].


·                 Portability


The “C” language has been created under UNIX and then - in a revolutionary exploit of recursion - the UNIX system itself has been rewritten in “C”. This language was extremely efficient while relatively small and started to be ported to other platforms, allowing the same to happen with UNIX.


Besides portability, another important characteristic of the UNIX system was its simplicity (the C logical structure could be learnt quickly, and UNIX was structured as a flexible toolkit of simple programs). Teachers and students found on it a good way to study the very principles of operating systems, while learning UNIX more deeply, and quickly spreading UNIX principles and advantages to the market.


This helped UNIX to become the ARPANET (and later Internet) operating system by excellence. The universities started to migrate from proprietary systems to the new open environment, establishing a standard way to work and communicate.




·                 Distribution method


Probably one of the UNIX most innovations was its original distribution method. AT&T could not market computer products so they distributed UNIX in source code, to educational institutions, at no charge. Each site that obtained UNIX could modify or add new functions, by creating a personalized copy of the system. They quickly started to share these new functions and the system become adaptable to a very wide range of computing tasks, including many completely unanticipated by the designers.


Initiated by Ken Thompson[53], students and professors from the University of California-Berkeley continued to enhance UNIX, creating the BSD (Berkeley Software Distribution) Version 4.2, and distributing it to many other universities. AT&T distributed their own version, and were the only able to distribute commercial copies.


In the early 80s the microchip and local-area network started to have an important impact on the UNIX evolution. Sun Microsystems used the Motorola 68000 chip to provide an inexpensive hardware for UNIX. Berkeley UNIX developed built-in support for the DARPA Internet protocols, which encouraged further growth of the Internet[54]. “X Window” provided the standard for graphic workstations. By 1984 AT&T started to commercialise UNIX. “What made UNIX popular for business applications was its timesharing, multitasking capability, permitting many people to use the mini- or mainframe; its portability across different vendor's machines; and its e-mail capability”[55].



·                 The UNIX wars


Several computer manufacturing companies[56] - like Sun, HP, DEC and Siemens - adapted AT&T and BSD UNIX distributions to their own machines, trying to seduce new users by developing new functions to benefit from hardware differences. Of course, the more differences between the UNIX distributions, more difficult to migrate between platforms. The customers started to be trapped, like in all other computer families.


As the versions of UNIX grew in number, the UNIX System Group (USG), which had been formed in the 1970s as a support organization for the internal Bell System use of UNIX, was reorganized as the UNIX Software Operation (USO) in 1989. The USO made several UNIX distributions of its own - to academia and to some commercial and government users –and then was merged with UNIX Systems Laboratories, to become an AT&T subsidiary.


AT&T entered into an alliance with Sun Microsystems to bring the best features from the many versions of UNIX into a single unified system. While many applauded this decision, one group of UNIX licensees expressed the fear that Sun would have a commercial advantage over the rest of the licensees.


The concerned group, leaded by Berkeley, in 1988 formed a special interest group, the Open Systems Foundation (OSF), to lobby for an "open" UNIX within the UNIX community. Soon several large companies also joined the OSF.


In response, AT&T and a second group of licensees formed their own group, UNIX International. Several negotiations took place, and the commercial aspects seemed to be more important than the technical ones. The impact of losing the war was obvious: important adaptations should be done in the complementary routines developed, some functions – together with some advantages – should be suppressed, some hardware innovative techniques should be abandoned in the name of the standardization. When efforts failed to bring the two groups together, each one brought out its own version of an "open" UNIX. This dispute could be viewed two ways: positively, since the number of UNIX versions were now reduced to two; or negatively, since there now were two more versions of UNIX to add to the existing ones.


In the meantime, the X/Open Company – company formed in guise to define a comprehensive open systems environment - held the centre ground. X/Open chose the UNIX system as the platform for the basis of open systems and started the process of standardizing the APIs necessary for an open operating system specification. In addition, it looked at areas of the system beyond the operating system level where a standard approach would add value for supplier and customer alike, developing or adopting specifications for languages, database connectivity, networking and connections with the mainframe platforms. The results of this work were published in successive X/Open Portability Guides (XPG).


·                 The Single UNIX Specification[57]


In December 1993, one specification was delivered to X/Open for fast track processing. The publication of the Spec 1170[58] work as the proper industry supported specification occurred in October 1994. In 1995 X/Open introduced the UNIX 95 brand for computer systems guaranteed to meet the Single UNIX Specification. On 1998 the Open Group introduces the UNIX 98 family of brands, including Base, Workstation and Server. First UNIX 98 registered products shipped by Sun, IBM and NCR.


There is now a single, open, consensus specification, under the brand X/Open® UNIX. Both the specification and the trademark are now managed and held in trust for the industry by X/Open Company. There are many competing products, all implemented against the Single UNIX Specification, ensuring competition and vendor choice. There are different technology suppliers, which vendors can license and build their own product, all of them implementing the Single UNIX Specification.


Among others, the main definitions under this specification on version 3 - which is a result of IEEE POSIX, The Open Group and the industry efforts – are the definitions (XBD), the commands and utilities (XCU), the system interfaces and headers (XSH) and the networking services. They are part of the X/Open CAE (Common Applications Environment) document set.


In November 2002, the joint revision to POSIX® and the Single UNIX® specification have been approved as an International Standard[59].


·                 Today


The Single UNIX Specification brand program has now achieved critical mass: vendors whose products have met the demanding criteria now account for the majority of UNIX systems by value. UNIX-based systems are sold today by a number of companies[60].


UNIX is a perfect example of a constructive way of thinking (and mainly: acting!), and it proves that the academia and commercial companies can act together, by using open standards regulated by independent organisations, to construct an open platform and stimulate technological innovation.


Companies using UNIX systems, software and hardware compliant with the X/Open specifications can be less dependent of the suppliers. Migration to another compliant product is always possible. One can argue that, in cases of intensive usage of “non-compliant” extra features, the activities required for a migration can demand a huge effort.


Figure 9 – UNIX Chronology[61]

2.2.3.         Linux

“Every good work of software starts by scratching a developer’s personal itch” – Eric Raymond


This discussion is not completely separated from the previous one. Developed by Linus Torvalds, Linux is a product that mimics the form and function of a UNIX system[62], but is not derived from licensed source code. Rather, it was developed independently by a group of developers in an informal alliance on the net (peer to peer). A major benefit is that the source code is freely available (under the GNU copyleft), enabling the technically astute to alter and amend the system; it also means that there are many, freely available, utilities and specialist drivers available on the net.




·                 Brief Hacker History


The hackers – not to be confounded with the “crackers[63] – appeared in the early sixties and define themselves as people who “program enthusiastically”[64] with “an ethical duty (…) to share their expertise by writing free software and facilitating access to information and computing resources wherever possible”[65]. After the collapse of the first software-sharing community[66] - the MIT Artificial Intelligence Lab - the hacker Richard Stallman quit his job at MIT in 1984 and started to work on the GNU[67] system. It was aimed to be a free operating system, compatible with UNIX. “Even if GNU had no technical advantage over UNIX, it would have a social advantage, allowing users to cooperate, and an ethical advantage, respecting the user’s freedom”[68]. He started by gathering pieces of free software, adapting them, and developing the missing parts, like a compiler for the C language and a powerful editor (EMACS). In 1985, the Free Software Foundation[69] has been created and by 1990, the GNU system was almost complete. The only major missing component was the kernel.


In 1991, Linus Torvalds developed a free UNIX kernel using the FSF toolkit. Around 1992, the combination of Linux and GNU resulted in a complete free operating system, and by late 1993, GNU/Linux could compete on stability and reliability with many commercial UNIX versions, and hosted more software.


Linux was based on good design principles and a good development model. By opposition to the typical organisation – where any complex software was developed in a carefully coordinated way by a relatively small group of people – Linux was developed by a huge numbers of volunteers coordinating through the Internet.


Portability was not the original goal. Conceived originally to run on a personal computer (386 processor), later on some people ported the Linux kernel to the Motorola 68000 series – used in early personal computers – using an Amiga computer. Nevertheless, the serious effort was to port Linux to the DEC Alpha machine. The entire code has been reworked in such a modular way that future ports were simplified, and started to appear quickly.


This modularity was essential for the new open-source development model, by allowing several people to work in parallel without risk of interference. It was also easier for a limited group of people – still coordinated by Torvalds – to receive all modified modules and integrate into a new kernel version[70].




·                 To be or not to BSD


Besides Linux, there are many freely available UNIX and UNIX-compatible implementations, such as OpenBSD, FreeBSD and NetBSD. According to Gartner, “Most BSD systems have liberal open source licenses, 10 years' more history than Linux, and great reliability and efficiency. But while Linux basks in the spotlight, BSD is invisible from corporate IT”[71]. BSDI is an independent company that markets products derived from the Berkeley Systems Distribution (BSD), developed at the University of California at Berkeley in the 60's and 70's. It is the operating system of choice for many Internet service providers. It is, as with Linux, not a registered UNIX system, though in this case there is a common code heritage if one looks far enough back in history. The creators of FreeBSD started with the source code from the Berkeley UNIX. Its kernel is directly descended from that source code.



·                 (Dis)united Linux


Recursion or fate, the fact is that Linux history is following the same steps than UNIX. As it was not developed using the source from one of the UNIX distributions, Linux have several technical specifications that are not (and will probably never be[72]) compliant with UNIX98. Soon, Linux started to be distributed by several different companies worldwide – SuSE, Red Hat, MandrakeSoft, Caldera International / SCO and Conectiva, to name some –, bundled together with a plethora of open source software, normally in two different packages - one aiming at home users and another for companies. In 2000, two standardization groups appeared - LSB[73] and LI18NUX[74] - and have incorporated under the name Free Standards Group, “organized to accelerate the use and acceptance of open source technologies through the application, development and promotion of interoperability standards for open source development”[75]. Caldera, Mandrake, Red hat and SuSE currently have versions compliant with the LSB certification[76].


Still in an early format, the current standards are not enough to guarantee the compatibility among the different distributions. In a commercial maneuver – to reduce the development costs – SCO, Conectiva, SuSE and Turbolinux formed a consortium called UnitedLinux, a joint server operating system for enterprise deployment. The software and hardware vendors can concentrate on one major business distribution, instead of certifying to multiple distributions. This is expected to increase the availability of new technologies to Linux customers, and reduce the time needed for the development of drivers and interfaces. Consulting companies can also concentrate the efforts to provide more and new services.


However, Red hat – the dominant seller in the enterprise market segment – has not been invited to join the UnitedLinux family before its announcement. Few expect it to join now. Also missing are MandrakeSoft and Sun Microsystems[77].


With the help from important IT companies, it’s expected from the Free Standards Group the same unifying role than the one played by the Open Group, which was essential for the UNIX common specification[78]. This is very important to give more credibility for the companies willing to seriously use Linux on their production environments. As in the UNIX world, the Linux sellers could still keep their own set of complementary products, which would be one important factor to stimulate the competition. The distributions targeting the home users can continue separated, by promoting the diversity needed to stimulate creativity, and by letting the natural selection chose the best software to be elected for enterprise usage. Darwin would be happy. Also would the users.



·                 Servers and desktops[79]


Linux already proved to be a reliable, secure and efficient operating system, ranging from low entry up to high-end servers. It has the same difficulty level than other UNIX platforms, with the big advantage of being economically affordable – almost everybody can have it at home, and learn it by practice. However, is it technically possible for everyone to install it and use it?


The main argument supporting all the open source software is that a good support can be obtained from service providers, besides the help from the open source community, by using Internet tools like newsgroups and discussion lists. Although, our question may have two different answers: One for servers, other for clients.


It is certainly possible for companies to replace existing operating systems with Linux, and the effort needed is mainly related to the conversion of the applications than to the migration of the servers or the operating systems. Several companies have been created using Linux servers to reduce their initial costs, and they worked with specialized Linux people from the beginning. Most of the companies replacing other platforms by Linux already have a support team, with a technological background, responsible by the installation and maintenance of the servers. Part of this team has already played with Linux at home and has learnt the basic knowledge. The other part is often willing to learn it, compare with the other platforms, and to discover what it has that is seducing the world.


The desktop users have a completely different scenario. This is because Linux is based on a real operating system, conceived to be installed and adapted by people with a good technical background, and willing to dedicate some time for this task. The main goal of most of the people (except probably the hackers themselves) installing Linux at home is to learn it, to play around, to compare with the other systems. The Linux main objective (by using the recursion so dear to the hackers) appears to be Linux itself. In its most recent releases, even if the installation process is not difficult as before, simple tasks as adding new hardware, playing a DVD, writing a CD or installing another piece of software, can quickly become nightmares. Linux can’t yet match Windows on plug-and-play digital media or the more peripheral duties.[80] One should continue to be optimist and hope that the next versions will finally be simpler. The open source community is working on it, via the creation of the Desktop Linux Consortium[81].


·                 Ubiquity … and beyond!


Linux is considered the only operating system that will certainly run on architectures that have not yet been invented[82]. Four major segments of Linux key marketplaces are:

§         Workload consolidation - One of the capabilities of Linux is that it makes it very easy to take distributed work and consolidate it in larger servers. Mainframes and some large servers support hundreds of thousands of virtual machines, each one running one copy of Linux.


§         Clusters – Linux performs very well when connected in clusters (due to its horizontal scalability), like the big supercomputing clusters existing in universities and research labs.


§         Distributed enterprise – The central management of geographically distributed servers is among the chief growth areas for Linux.


§         Appliances –Linux is found as an embedded operating system in all kinds of new applications, like major network servers, file and print servers, and quite a number of them new kinds of information appliances. It’s very cost effective, reliable and fast. In addition, the open standards facilitate their operations.


2.2.4.         Windows 


The first Microsoft’s product – in 1975 – was BASIC[83], installed in microcomputers used by hobbyists. In 1980, IBM started to develop the personal computer (PC) and invited Microsoft to participate in the project by creating the operating system. Microsoft bought, from a small company called Seattle Computer, a system called Q-DOS[84], and used it as a basis for MS-DOS, which became the operating system of choice, distributed by IBM as PC-DOS.[85] By 1983, Microsoft announced their planning to bring graphical computing to the IBM PC with a product called Windows. As Bill Gates explains, “at that time two of the personal computers on the market had graphical capabilities: The XEROX Star and the Apple Lisa. Both were expensive, limited in capability, and built on proprietary hardware architectures. Other hardware companies couldn’t license the operating systems to build compatible systems, and neither computer attracted many software companies to develop applications. Microsoft wanted to created an open standard and bring graphical capabilities to any computer that was running MS-DOS[86].


·                 First steps


Microsoft worked together with Apple during the development of the Macintosh, and created for this platform their two first graphical products: a word processor (Microsoft Word) and a spreadsheet (Microsoft Excel). Microsoft also cooperated with IBM during the development of OS/2, which was aimed to become the graphic replacement for MS-DOS.


Using this knowledge, and a lot of ideas from the XEROX research, Microsoft release the first version of Windows in November 1985[87]. The impact of OS/2 was very limited, as it did not provide full compatibility with the old MS-DOS software. On the other hand, Windows was a large success mainly because it supported the existing MS-DOS character-oriented applications, in parallel with exploiting the potentials from the new graphical software.


Application support for Windows was initially sparse. To encourage earlier application support, Microsoft licensed a free of charge runtime version of Windows to developers, which made their programs available to end-users. This runtime version allowed use of the application although it did not give the benefits that the full Windows environment provided. With version 3.1, Windows acquired maturity, reducing the incredible number of bugs - mainly related with the user interface, and with the constant need of rebooting the system - and with the wide availability of graphic applications. Its popularity blossomed with the release of a completely new Windows software development kit (SDK) - which helped software developers focus more on writing applications and less on writing device drivers – and with the widespread acceptance among third-party hardware and software developers. The bugs are persistent, and today are the main source of virus by opening security flaws.


·                 Different families with different editions


Microsoft decided to keep the compatibility with the MS-DOS applications to avoid losing customers. However, this also avoided Windows desktop systems to be stable, and reduced the pace of innovation. Microsoft then started to develop a completely new desktop system from scratch, oriented to business customers that needed more stability. After 1993 two different families of desktop operating systems co-existed: the Windows 3x (that later evolved to Windows 9x and Windows Millennium), descended from MS-DOS and the Windows NT (that later evolved to Windows2000), completely built around the graphic interfaces and new hardware features. In 2001, Microsoft abandoned the 3x family and used the base code from NT to create the Windows XP, with two different packages and prices: one “edition” aimed for home users, another for professional use[88].

Figure 10 – Windows client evolution[89]


In July 1993, Microsoft inaugurated its Windows server family with the release of Windows NT Advanced server 3.1[90]. It was designed to act as a dedicated server (for tasks as Application, Mail, Database and Communications Server) in a client/server environment, for Novell NetWare, Banyan VINES, and Microsoft networks. The next releases improved the connectivity with UNIX environments (3.5), integrated a web server (4.0) and consolidated the web facilities with ASP (2000). To follow is the Windows .NET server[91], which aims to better exploit the XML Web services and the .NET framework. The different editions for the server families are Standard, Enterprise, Datacenter and Web[92].


Figure 11 – Windows server evolution[93]


·                 Easy-to-use, easy-to-break


The main advantage of the windows families – over Linux and UNIX - is their easy installation and operation. As we saw, Microsoft copied the concepts from Apple Macintosh and always based their windows products in graphic interfaces, with intuitive icons opening the doors for all the tasks, from running the applications to configuring the hardware and changing the software options, colours and sounds. This seems to be a major benefit for end users, that don’t need to bother with learning the concepts of operating systems to be able to write a letter, scan some photos, mix everything and print. The problems start to appear when something changes, like the version of the operating system, a new hardware component or simply when an inoffensive application is installed or removed from the computer. These tasks often need an intervention from a specialist, or a complete reinstallation of the windows system. This happens even with the recent XP releases, despite Microsoft publicity stating the opposite.


Finally, the main technical advantages disappear, and only the market dominance, compatibility of the document formats, and marketing strategies convince the user to keep the windows system, rather than installing Linux or buying a Macintosh system.


·                 Embrace and Extend


Microsoft strategy always consisted in identifying the good opportunities, react quickly and offer a solution (often without taking care of the quality) to conquer the market and later improve it to keep the customers. Again, as it was the case for IBM with the mainframes, marketing strategies revealed to be more important than technological features, paving the way for “de facto” standards.


Windows is extremely important for Microsoft’s marketing strategies, serving as a Trojan horse to introduce “free” Microsoft programs. This happened in 1995, when Internet Explorer quickly gained an impressive market place in a short time – again, instead of developing a concept and a product[94], Microsoft simply acquired Mosaic from the company Spyglass and make quick modifications transforming it into Internet Explorer. After, with the development of extensions to the standard HTML language, it almost eliminated Netscape from the market.


This drive us to the conclusion that Microsoft practices aim to conquer a complete monopoly – not only for operating systems, but also for applications, appliances, the internet and content[95] – through the complete elimination of the competition. This has already been analysed by the American and European justice departments.


·                 Hardware Independence


One of the main reasons behind Windows’ success is the independence from the hardware supplier. If the processor chip is usually built by Intel and AMD, the computers can be manufactured by any company following the specifications from the PC architecture, or even assembled at home, by using standard components available in any electronic shop. On the other hand, the Apple Macintosh and IBM PS/2 architectures force the customer to buy the hardware and software from the same supplier. There’s no compatibility with other vendors, thus the cost remains higher than the PC/Windows platforms, which benefit from the competition and the higher market share to decrease the production costs.


Yet, the windows systems remain dependent of the PC architectures, and this may be a serious disadvantage by opposition to the portability offered by Linux systems. This is important to understand what is behind the strategies adopted by the Microsoft competitors, to be studied on the next chapter.



·                 Social Organization


One important difference between the proprietary MS-DOS and Windows families and the open systems is not technical, but social. There is not such a concept as Windows hackers[96]. Windows environments were conceived to run alone, not in networks. The UNIX systems have been built with strong networking facilities, since their first versions, what allowed creating a large community that used, analysed, developed and cooperated for its improvements. Moreover, the UNIX systems appeared in the academic world, which favoured this community to be extremely creative and looking for technological innovations. This concept, also known as peer-to-peer (P2P), obtained its climax with Linux, which has entirely constructed (and still evolves) through the Internet.


As well defined by Eric Raymond[97], “the MS-DOS world remained blissful ignorant of all this. Though those early microcomputer enthusiasts quickly expanded to a population of DOS and Mac hackers order of magnitude greater than that of the ‘network nation’ culture, they never become self-aware culture themselves. The pace of change was so fast that fifty different technical cultures grew and died as rapidly as mayflies, never achieving quite the stability necessary to develop a common tradition of jargon, folklore and mythic history. (…) The fact that non-UNIX operating systems don’t come bundled with development tools meant that very little source was passed over them. Thus, no tradition of collaborative hacking developed.”.


Complementary, as Himanen explains, “Bill Gates (…) gained hacker respect by programming his first interpreter of the BASIC programming language (…) [but] in Microsoft’s subsequent history, the profit motive has taken precedent over the passion”[98].


2.2.5.         Other Operating Systems


·                 Apple Mac/OS


Released in 1984 and integrating the hardware and software into the same platform, the Apple Macintosh was the first to have good graphical interfaces to perform all the basic functions. Apple refused (until 1995) to let anyone else make computer hardware that would run it, limiting its success and avoiding it to become the standard for graphical platforms.


The technical comparison with PC and Windows is not easy to be done, and the eternal discussion is far from coming to an end. Apple addicts always considered the Mac as a more stable platform, and with best results with multimedia applications. The counterargument is that the modern windows / Intel systems improved their graphic and sound systems, with the help from external cards, and could produce the same quality. The reality today is that the Mac systems are more expensive, and are still preferred by designers and artists to produce graphic, music and images.


The new version, MacOsX, is based in the UNIX operating system OpenStep, and implement Vector-based graphic interfaces.[99]


·                 IBM OS/2 


It’s surprising that IBM is still maintaining versions of their OS/2 Warp operating system. In 1984, after having realized the real market potentials of personal computing, IBM decided to create a close platform (PS/2) with a stronger architecture than the IBM/PC – with mainframe customers in mind - and a solid operating system (OS/2), to be able to run professional applications and compete with the DOS, Windows and Macintosh families. The smaller prices of the PC clones, which already had a large installed base, and were sold with an incorporated DOS/Windows system, avoid this to happen. Contrarily to IBM hopes, the price was a more important factor than reliability, and the OS/2 platform has never been largely used.


·                 IBM OS/400


The only one that can unequivocally be called a “minicomputer” operating system, the OS/400 is the evolution of the IBM midrange System/36 and System/38 systems, implemented on PowerPC chips. Despite the lack of good technical reasons to keep both Unix and OS/400 platforms, the large installed base of these systems is able to guarantee their continuity.

Additionally, the current OS/400 gives the users the ability to run Java, Windows and UNIX applications (via PASE - Portable Application Solutions Environment which supports a subset of the AIX environment).


2.2.6.         Classification


Considering two major criteria discussed in the previous paragraphs – scalability and openness – the operating systems can be classified by using the following chart:











Figure 12 – Operating systems – Openness and scalability


Scalability is the ability of increasing the system throughput by adding processors or new systems, with a low impact in the efforts for managing the system (license costs and human resources). Linux outperform the other systems due to its capacity of running in virtually all hardware platform and machine sizes, its reduced cost, the openness of its source code and the usage of open standards and protocols.














Figure 13 – Operating systems – set-up costs and proven reliability


The number of installed mainframe and UNIX systems for critical systems in large companies, in addition to the decades of experience and fine tuning, help these systems to have more confidence from IT specialists. The reduced initial setup costs[100] for windows and Linux platforms justify their choice when price is an important element. Goldman Sachs considers Linux as “Enterprise Class”, and estimates that Linux will soon replace windows in medium-large servers[101]. The cost analysis and comparisons will be detailed on chapter 6.4.


2.3.        Communication


The co-existence of different standards on the hardware and software domains may stimulate the competition, the innovation and the market. For the network infrastructures, the absence of widely accepted standard and protocols can simply avoid the communication to happen in a global way.


One of the first problems identified when the Internet ideas started to flourish was “to understand, design, and implement the protocols and procedures within the operating systems of each connected computer, in order to allow the use of the new network by the computers in sharing resources.”[102]


The free exchange of information via the Internet, independently of the hardware or operating system we may use, is possible due to the previous definition of standards, which we may classify in three different tiers: The communication via the network, the addressing of each node and the content formatting and browsing. Standard bodies are responsible for their definition, publication and conformity. Let us discuss the communication and addressing tiers. The content will be discussed in details on the chapter 4 (page 70).

2.3.1.         Network


As we saw in chapter 2, the first mainframes and minicomputers performed very specific tasks, independent of any other computer, and the users and operators were connected locally, normally in the same building than the machines. When distant systems started to connect with each other, and to remote users, clear conventions needed to be established.


·                 The OSI model


The OSI reference model was developed by the International Organization for Standardization (ISO) in 1984, and is now considered the primary architectural model for inter-computer communications.


OSI is a conceptual model composed of seven layers, each specifying particular network functions. It only provides a conceptual framework. Several communication protocols have been developed using it as a reference, allowing their interoperability.


Figure 14 – The OSI model - Seven layers and two categories


The seven layers of the OSI reference model can be divided into two categories: the upper layers (which deal with application issues and generally are implemented only in software) and the lower layers (which handle data transport issues).


·                 The Internet Protocols


In the mid-1970s, the Defense Advanced Research Projects Agency (DARPA) started to develop a packet-switched network that would facilitate communication between dissimilar computer systems at research institutions. The result of this development effort was the Internet protocol suite[103] that contained several basic network protocols. Among others, Transmission Control Protocol (TCP) and the Internet Protocol (IP) are the two best known and commonly used together[104].


One of the main reasons of their quick adoption by the research institutions (and later the whole market) was their openness. The Internet Protocol suite is nonproprietary, born in an academic environment close to the UNIX developments, and soon both work in synergy. TCP/IP was included with Berkeley Software Distribution (BSD) UNIX to become the foundation of the Internet[105].

Figure 15 – Correspondence between the OSI layers and some Internet Protocols.


·                 SNA


In 1974, IBM introduced a set of communications standards, called SNA[106], which was extremely convenient to the mainframes hierarchical topologies. Like other IBM definitions for hardware and operating systems architectures, it is a proprietary protocol, but clearly defined and open for the use of other manufacturers. This allowed IBM and many other companies to provide servers communication hardware and programming products, which could be connected by the usage of common communication definitions, hardware specifications and programming conventions. The administration of a SNA network is centralized, what improves its security while reducing its flexibility.


IBM tried to evolve SNA to an open-standard known as High-Performance Routing (HPR), without success. SNA is still used in the core mainframe connections, although it is being replaced by TCP/IP in distant connections, due to pressures of intranets and the Internet, and for more flexibility.


2.3.2.         Addressing


A set of techniques is used to allow the identification of each single machine in the world, to allow the Internet packets to be distributed efficiently. Each computer with capability to be connected to the Internet receives from its manufacturer a single and unique address (called MAC address[107]). When a computer connects to an Internet or intranet server, it receives a network address[108].


As the IP addresses are quite difficult to remember, a domain name is created for important servers (like web or FTP servers)[109]. A hierarchy of systems have been created to locate a domain name. It is called DNS[110]. The intelligence behind the DNS servers is provided by the open source program BIND, and soon the “Domain Wars” started to decide who would control the domains.


The conflicts have been solved by a policy specifying the codification of roles in the operation of a domain name space:


§         Registrant - The entity that makes use of the domain name.


§         Registrar - The agent that submits change requests to the registry on behalf of the registrant.



One non-profit organization has been created, ICANN[111], which the role is to oversee administer Internet resources including Addresses (by delegating blocks of addresses to the regional registries), Protocol identifiers and parameters (by allocating port numbers, etc.) and Names.


2.3.3.         The Internet


·                 History


The Internet is the result of many technologies developing in parallel, around the Advanced Research Projects Agency (ARPA, today called DARPA[112]) of the U.S. Department of Defense. Motivated by the launching of the first sputnik, ARPA started to design a communications system invulnerable to nuclear attack. It was the ARPANET[113] project, based on packet switching communication technology. “The system made the network independent of command and control centers, so that message units would find their own routes along the network, being reassembled in coherent meaning at any point in the network”[114].


Important is to notice that, since the beginning, the concept around the network had stronger cultural and social than technical motivations: "The ARPA theme is that the promise offered by the computer as a communication medium between people, dwarfs into relative insignificance the historical beginnings of the computer as an arithmetic engine."[115]


J.C.R. Licklider[116] perceived the spirit of community created among the users of the first time-sharing systems.  He envisioned an “'Intergalactic Network”, formed by academic computer centers. His ideas took almost one decade to become reality: On October 25, 1969 a host-to-host connection has been successfully established between the University of California Los Angeles (UCLA) and the Stanford Research Institute (SRI), creating the network roots for the Internet.


In the same time – as we already discussed – UNIX was born and the Internet Protocols have been defined. In 1973, 25 computers were connected using the ARPANET structure[117], opened to the research centers cooperating with the US defense Department. Other networks - using the ARPANET as the backbone communication system – started to appear, aimed to connect scientists from all disciplines, military institutions. This network of networks, formed during the 1980s, was called ARPA-INTERNET, then simply INTERNET, still supported by the Defense Department and operated by the National Science Foundation.


In 1995, motivated by commercial pressures, the growth of private corporate networks, and of non-profit, cooperative networks, the Internet was privatized. About 100,000 computer networks were interconnected around the world in 1996, with roughly 10 million computers users.[118] The internet has posted the fastest rate of penetration of any communication medium in history: in the United States, the radio took 30 years to reach 60 million people; TV reached this level of diffusion in 15 years; the Internet did it in just three years after the development of world wide web.[119]


·                 The World Wide Web


In addition to being a means of communicating via e-mail, the Internet has become a means of propagating information via hypertext documents. Hypertext documents contain specific words, phrases, or images that are linked to other documents. A reader of a hypertext document can access these related documents as desired, usually by pointing and clicking with the mouse or using the arrow keys on the keyboard.


In this manner, a reader of hypertext documents can explore related documents or follow a train of thought from document to document, in the intertwined web of related information. When implemented on a network, the documents within such a web can reside in different machines, forming a network-wide web. Similarly, the web that has evolved on the Internet spans the entire globe and is known as World Wide Web.[120]


·                 Standard Bodies


A wide variety of organizations contribute to internetworking standards by providing forums for discussion, turning informal discussion into formal specifications, and proliferating specifications after they are standardized.


Most standards organizations create formal standards by using specific processes: organizing ideas, discussing the approach, developing draft standards, voting on all or certain aspects of the standards, and then formally releasing the completed standard to the public. They are normally independent, aimed to stimulate a healthy competition, but they are often influenced by companies and lobbies.


·                 The Internet Standardization


Some of the organizations that contributed to the foundation of Internet with internetworking standards may be found in the chapter Appendix B. The heart of Internet standardization is the IETF, which coordinate the developments in working groups. According to Scott Bradner, co-director of the Transport Area in the IETF, “IETF working groups created the routing, management, and transport standards without which the Internet would nor exist. They have defined the security standards that will help secure the Internet, the quality of service standards that will make the Internet a more predictable environment, and the standard for the next generation of the Internet protocol itself. (…) There is enough enthusiasm and expertise to make the working group a success”[121].


Apart from TCP/IP itself, all of the basic technology of the Internet was developed or refined in the IETF.


Resulting from the working groups are the base documents in the standardization process, known as RFC (Request For Comment)[122]. The RFC series of documents on networking began in 1969 as part of the original ARPANET project. Initially they were submitted for comments (as the name indicates) but, after the Internet has been developed, they ave generally gone through an extensive review process before publication. In the end, they become proposals for standards (and following the standard track possibly become Draft Standards and Internet Standards), best current practice guides, informational guidelines, etc. They are freely available on the Internet and may be republished in its entirety by anyone. Interesting examples of RFC are the 2026[123], which recursively describes the Internet standards process and the 3160[124], known as “The TAO of IETF”.


The proposed standards are analysed by the IAB, which may use them to create the final standards. The research is done by the IRTF.


Also important are the IANA