In the past, the current situation and prospects of Web Services (upper) ORIGINAL: http://webservices.org/article/articleprint/663/-1/24/ Original title: The Past, Present and Future of Web Services, part 1 Author: Uche ogbuji Original Published: September 28, 2002 Translators: Chen Jian (JCHEN@263.net) Date: October 10, 2002 Copyright Notice: This article English copyright belongs to the original author uche ogbuji and WebServices All the Chinese translation of this article is not allowed to use this paper for any commercial nature. Welcome to, but please keep this article integrity
Introduction The big propaganda of Web Services (HYPE) has been close to the peak, which has become the most popular speculation of popular media. This publicity offensive is nothingordual with other technologies in full development and going to mature. Regardless of the interest of the media, Web Services is undoubtedly an important technology that is very optimistic about development prospects. Those motives that appear to Web Services, some specific technologies are better than competitors, as well as Web Services, have a thorough understanding of companies and developers will succeed in the use of Web Services.
is based on this reason, I will start with the history of Web Services. This is not for nostalgic purposes, Web Services can give birth to commercial and technical environments and incompetent participants (companies or organizations) in their development process will have an important impact on the future of Web Services. You may have noticed this trend, such as a group similar to structured information standard propulsion organization (OASIS) is playing a role in which the Web Services develops security, workflow and transaction processing and other protocol standards. Interestingly, Oasis has been seen as an opponent of the mainstream technology of Web Services.
Web Services' performance stations The development of distributed applications has become an important field of development in traditional computing techniques by centralized host calculation to peer-to-peer computer and workstation network transition phases. During this trend, IT managers are still experts in their field. The strategy of distributed development is limited to the IT manager accepts the necessary input and submits the necessary report to the management. Running and maintaining a well-integrated data center is the key, and support for asynchronous platforms and environments is not that important. In this case, a department such as electronic data exchange (EDI) is usually present as a completely independent entity in the enterprise.
Although almost all Web Services has developed from the small machine era, because of some reasons, in the history of distributed computing, the small machine era is often ignored. This is probably because of the revolutionary rise of the PC in the same period, covering the rays of the small machine era. But until the Internet is invested in a wide range of business applications, the PC does not have a prominent contribution to the field of distributed calculations. In order to organize and increase the scalability of the data center, the service is dispersed to multiple workstations, which requires a range of communication mechanisms and underlying application integration mechanisms including synchronous and asynchronous. As a result, this period of this period is developed by the distributed message communication (for example, DEC VMS, TANDEM, HP, and Sun's UNIX system). The complexity is even more than today. People are soaked. IBM portally with MQSeries to enter the distributed newsletter. After seeing that the application can run from a small machine until the demand on its large host, IBM acquires the popular EZBRIDGE software at the time and develops MQSeries based on it. MQSeries will be uncommon from that era until now. However, news communication technology requires programmers who are used to procedural programming language and solve problems with new ideas. The programmer hopes to access the remote process with a simple function call method that you are familiar with. In the late 1980s, the launch of the distributed computing environment (DCE) tried to standardize multiple mutually competitive remote processes. This effort is intentionally ignored news communication technology, and mainly due to political reasons, DCE did not receive extensive support in the industry. At this point, a new generation (but not necessarily better) distributed computing technology begins to emerge. During this period, IT managers began to manage high-level, information systems, became the foundation of the company's strategy, and increased in the investment budget. The reality in the organization means that most companies' calculation technology focus is no longer limited to a single data center. In contrast, all kinds of departmental systems have explosive growth. System integration instead of single platform criteria becomes the most important consideration in technology selection. IT managers are now looking for standardization of network technology. Because of the benefits of object-oriented technology promises, the code reuse, reducing costs, and the improvement of return on investment, IT companies began using the object system as the standard of software development. The result of this is that the distributed technology that emerged in this stage has hopped a deep object technology. Like DCE, CORBA (General Object Request Agent Architecture) is also a product of the industry alliance attempts to standardize distributed process technology. This time, large-scale Object Management Group (OMG) will focus on the access requests of remote objects in cross-platform applications. Since the CORBA is trying to transparency transparency of the object status and life cycle, it is not as good as message mechanisms and DCE ideals in scalability. The same problem also plagues Microsoft's Remote Object Protocols that compete with CORBA: Component Object Model (COM) and Distributed Component Object Models (DCOM). At the same time, E-mail and web proved to be the most successful distributed architecture ever, and the distributed development technology used by the designer fully utilizes the universality of the message communication technology and the Internet. These major manufacturers are generally supported by the purpose of reducing risk. During the same period, other specialized distributed technology also appeared successively. Java's popularity leads to the emergence of RMI (remote method call) protocol. After MQSeries succeeds, Microsoft and Java have also launched their own news communication technology.
On the occasion of the new millennium, based on the needs of information systems and the experience of network technology, the new generation of distributed computing technology is coming. The requirements for distributed computing techniques include: a distributed operation in a single application and a call of common services between different applications. In other words, it is to support developers and system integrators. Suitable for information exchange between organization and inter-organization, requiring cross-platform support and data-driven. Together with existing Internet infrastructure harmoniously. There is good scalability when the number of nodes, the number of heterogeneous nodes, and the complexity of the node are increased. Powerful international support. Fault tolerance. Node tightly coupled networks typically exist of single-point failure, which is more serious in distributed systems. Very strong support for general software development and business process management tools from popular vendors. While supporting the easiest request / response mechanism, it also provides complex process collaboration, transaction, security support when necessary. Web Services passed the eye-catching steps directly on its high-end UNIX platform into modern Web Services, which enters modern web services. From the early 1990s to the mid-term, HP laboratory began to study how to solve the technical and cost of distributed systems. The research results of HP were known as E-Speak, which was officially launched in the second half of 1999. E-SPEAK is committed to solving the vast majority of demands listed in the end, perhaps the first Web Services technology of the industry, of course, is also the first commercial web services technology. E-Speak uses a general protocol such as HTTP, the representation of data is XML, and various networking systems appear as "electronic services" ("e-services") that can quickly plug the data stream. Unfortunately, E-Speak's philosophy is stronger than the current Web Services technology, HP has recently decided to fade E-Speak, and support more mainstream Web Services.
TheUserland community also tried to use HTTP and XML technology to meet the above needs. Userland's Dave Winer leads the development of XML-RPC. XML-RPC is a simple system for calling remote methods, and its protocol text is only a short number of pages. Currently, XML-RPC is still very popular in opening the original code. Open the project and many open projects and many open and licenses free implementation make XML-RPCs have good interoperability and low cost. However, due to the grassroots of XML-RPC from the grassroots and earlier launch time, it is inevitable to have some significant shortcomings. For example, XML-RPC adheres to the use of ASCII strings (although it is using international support for good XML standards), this causes it to be basically used in English. Moreover, XML-RPC is also more casual in the selection of data types. However, more importantly, XML-RPC is limited to a simple request / response service using a highly unified and structured message format. At the same time as XML-RPC, there are other more common XML messaging mechanisms. Although most of them are more suitable for the content dump of the program language structure and the content dump of the database, not for the document-oriented newsletter, but compared to strict RPC mode It is still more flexible. The most famous of which is the Web Distributed Data Exchange Protocol (WDDX) proposed by Allaire, and a related community is currently continuing to develop. At the same time, the XML and Internet protocols also brought revolutionary impact on other technical groups like EDI industry. First, an EDI running on SMTP (E-mail) has occurred, and the HTTP (Web) is also adopted by EDI in order to avoid value-added network (VANS) high transaction costs. Connected, such as European CEN / ISSS and US XML / EDI groups begin to develop technologies encoding EDI transactions into XML, as EDI transactions are named. This series of trends makes the early Web Services mainly solved the problem of enterprise application integration (EAI), but is mainly used to simplify B2B transactions. These early XML / EDI systems utilize existing stable and universal EDI process collaboration, security, etc., which is currently still lacking in Web Services. These efforts have led to a formal standard called e-commerce XML (EBXML). The supporters of EBXML are mainly from the EDI camp, but it is generally considered to be a SUN that is good at the process and objects. Since the end of 1999, EBXML entered the June development cycle. EBXML is developed and maintained by the SGML / XML industry pioneer Oasis and the United Nations trade promotion and e-commerce organization (UN / CEFACT) developed in traditional EDI. back to 1998, a specification for structured exchange XML documents - Simple Object Access Protocol (SOAP) is brewing in a small range of organizations, including software giants Microsoft. SOAP was officially released until the second half of 1999. History of Distributed Computing
SOAP reproductive hyperplasia SOAP is born to cause disputes between all parties. Although the special type of system adopted from SOAP is full of controversies with the SOAP camp (by Microsoft leaders) or EBXML (by Sun leaders), the main industry manufacturers will become the next heavyweight technology for Web Services (The next Big " It's all right. SOAP Since the same community of XML-RPC, SOAP, Soil, so it is popular in the grass root Web Services camp. SOAP is not as simple as XML-RPC, but it does solve some problems in early norms. Developers who open source code were surprised to find that almost all commercial system vendors supported this open protocol. In fact, think about XML success, this is not surprising. The emergence of SOAP provides a good opportunity for distributed development to the strict limit of larger vendors and associations, so, various SOAP development organizations have emerged in the spring. is just a communication protocol. There is a significant indication that the standardization of metadata (metadata) of Web Services is important. In terms of creating this special language, many aspects have made efforts. WebMethods proposed by the Web Interface Definition Language (WIDL) is one of the earliest standards, and its goal is to use the first generation Web Services system like XML-RPC and WDDX. The WIDL design is equivalent to the interface definition language as the CORBA and COM base, but it appears in XML. Microsoft developed a Service Description Language (SDL) and SOAP Contract Language (SCL) in 2000 for the Web Services node. Microsoft also developed the Web Services Discovery Protocol (DISCO) for Web Service Information Registration and Find, which can find the service described with SCL. IBM launched a range of norms to compete: and SDL similar to SCL Visible Network Service Specification Language (NASSL), and DISCO Similar Service Publishing and Discovery Protocol (ADS). These standards are integrated into the IBM AlphaWorks Web Services kit. Companies such as IBM, Microsoft, and Ariba finally proposed the Web Services Description Language (WSDL) based on these agreements mentioned above.
These three companies also integrate other proprietary discovery systems, proposed a Web Services directory system - General Description, Discovery, and Integration Protocol (UDDI). UDDI includes white pages, yellow pages and green pages. UDDI was launched as a product of 36 companies participating in alliances, and the members of the alliance have exceeded 100. The definition of this product is very detailed and highly formified, which is different from SOAP and WSDL. SOAP and WSDL specification text is easy to understand and easy to implement. This difference reflects the status quo of Web Services: the evolution of underlying technology details such as core communications and service descriptions is Bottom Up, which uses a range of language and tools that can be available for free; and discovery and business / legal description Then, according to the centralized information authorization and certification, it is evolved by top down.
This has led to the differentiation of Web Services in "Personality"). First, the Web Services grassroots represented by the "Desperate Perl Hacker") is water, but the whole company's strategy is laid. Second, enterprise-level Web Services as the basis of e-commerce strategy, etc. Currently, most of the successful Web Services is concentrated in the grassroots level. Enterprise Web Services represented by UDDI has not yet found their core value (and in some cases, even denying the lessons learned for a long time of the EDI group). Developer Station to the front desk W3C Web Services, W3C Workshop On Web Services, WSWS, held in April 2001, is a plan for the future development of Web Services. Previously, Web Services was mainly developed by a grassroots level or an independent group such as uddi.org from outside W3C. W3C's support for Web Services is natural. As, it is also the same as other Web standards such as HTML, XML. WSWS's goal is to determine the form and target of the W3C related to Web Services. W3C has established an XML protocol working group, XMLPWG, although so far, the Working Group does not complete how much substantive work in addition to a series of XML recommendations and candidate protocols. For WSWS, XMLPWG will continue to be enrichment to extend SOAP into a perfect W3C recommended standard.
For Web Services, the opportunity is to enable a variety of technical strategies to get new students. WSWS is considering achieving a series of advanced features on the basis of the basic protocol: IBM's Web Services Node Language (WSEL) attempts to resolve network management of Web Services (QoS), Web Services Streaming Language (WSFL) It is committed to the process collaboration of Web Services. HP's Espeak technology puts forward a broader and ambitious Web Services strategy, discussing the core concepts of all kinds of specific services, and the need for operational environments, especially for small embedded devices. Microsoft also emphasizes QoS and jointly developed with IBM. Jamcracker and BEA emphasize the importance of Web Services in integration. VeriSign emphasizes the importance of security and the role of digital authentication. Novell emphasizes the management of authorization and certification in directory services. Some other developers are just a proprietary framework that supports Web Services development and deployment, and proposes it as a model that can appear in the future. Wsws also has a representative from the Web Services grassroots (for example, Userland's Dave Winer, XML-RPC and SOAP) and representatives from Oasis and EBXML. The latter has recently concluded an internal argument of a Web Services association and decided to adopt a SOAP over e-mail with attachment with annex EMAIL instead of a more refined special news communication protocol that was previously developed. . The author also invited to express the paper on how to use the W3C's resource description framework standard (RDF) to integrate web services and other metadata systems.
Progress in the protocol stack The main purpose of WSWS is to build the "protocol stack" of Web Services or the architecture. Standards such as QoS (Service Quality), Security, Process Collaboration (Orchestration), and Transaction Management will find their own place in this protocol stack. SOAP and WSDL have established the status of the Web Services core standard, so the main vendors fill the combat parties in the protocol stack of the protocols into the main melody in the second half of 2002. security has always been specially valued. It is easy to understand that strong security must be guaranteed before web services become popular communication mechanisms outside the company's firewall. Safety is manifested in multiple aspects, one of which is to ensure that the content of the transmission is not tampered with. W3C's XML Signature Working Group is committed to developing a digital signature system for an XML document, supports protocol specifications such as Canonicalization (C14n). C14n converts an XML document into a standard format to avoid misjudgment of a digital signature system for factors such as an XML attribute. XML Encryption Working Group is committed to encrypting technology to develop XML encryption syntax and processing specifications that include encrypted data and guarantee results for XML documents that have good format (Well-Formed). XML Key Management Working Groups Develop a simple Web Services specification for managing digital keys and creditation tokens. 2002 new standards also include a security assertion mark language (SAML) and WS-Security Specification Framework. I will discuss these specifications in the lower part of this article. Business processes and workflows are another active areas of standard development in the protocol stack. EBXML is an early member of this field. The Commercial Process Normative Mode (BPSS) in the EBXML protocol is provided with its registration and storage standards for the management of business partnerships and protocols. It also provides support for the management, security, and service quality of continuous operation transactions. Early development of the transaction rights marker language (XAML) proposed by IBM, HP, Oracle, Sun et al. This protocol has been combined into the development of trading specifications for other Web Services. IBM's WSFL and WSEL are respectively proposed for workflow and service quality (QoS). Microsoft proposed a workflow protocol called XLANG. WSFL and XLANG are extension to WSDL. As people expect, these two standards are merged into a more common business process language WS-CORDINATION. In the lower part of this article, I will discuss WS-CORDINATION, WS-Transaction and BPELWS. Get into 2002 When we step into 2002, Web Services got a long-term progress at all levels. In the grassroots, multiple developers groups begin to solve the problem of interoperability in the early Web Services audio. In the company, the Web Services protocol stack gradually forms, and developers are urgently expected to improve the Web Services related specification as soon as possible. In the second part of this article, I will outline the situation of Web Services in the current (2002) and looking forward to its future development.
About the author: Uche Ogbuj is the founder and consultant of Fourthought Inc.. His company provides professional XML solutions for corporate knowledge management, including software development and consulting services. FourtHough developed an open source platform for XML, RDF, and knowledge management applications. Mr. Ogbuji is a computer engineer and writer. He was born in Nigeria, and now lives in the US Colorado Boulder. You can contact him through email. About the translator: Chen Jian, IBM China Development Center Software Engineer. Pay attention to J2EE, Web Services, object-oriented, software engineering and other technologies. Born in Sichuan, the country of Tianfu, now Beijing work and life. You can contact him through email.
