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Modeling Web Applications Using Java And XML Related Technologies Introduction Standards can drive revolutionary changes in technology: consider the impact that SQL has had on the database market, or consider that the World Wide Web was launched by the combination of HTML, HTTP, URL, and SSL. My belief is that protocol standards (XML, Web services) and programming standards (Java and the. NET alternatives, XML Query, etc. ) will have a similarly profound impact on integration. Integration encompasses a broad range of information technology (IT) needs: Enterprise application integration (EAI): Directly interconnecting two or more business applications over intranets (that is, behind corporate firewalls) Business-to-business integration (B 2 BI): Directly interconnecting the business applications of one company with those of a business partner across the Internet or a virtual private network User interface (UI) integration: Aggregating and personalizing UI across applications so that the human user experiences a single unified "Web flow" (e.
g. , Java page flows within a portal), bringing together those disparate back-end systems Data integration: Aggregating data queried from disparate applications and data stores in order to define a unified view of a business object -- for example, creating a unified "customer" schema by combining data from a customer relationship management (CRM) system, an Enterprise Resource Planning (ERP) system, and so on Modeling Using Java and Xml for Web Applications Today Today, the integration market remains largely fragmented across proprietary solutions, none of which scale to meet the needs of our Web-oriented world. It is also important that proprietary integration technologies generally require the user to run a particular vendor's software on all participating nodes. Convincing a worldwide company and all of its business partners to run the same proprietary integration software just will not fly. At the same time, integration remains very expensive -- by various measures consuming 70 +% of discretionary IT funding, and remains sufficiently complex that organizations tend to only integrate applications as it becomes a business imperative. Clearly, the industry must do better. We are convinced the answer lies in extending the Web from the UI platform it is now (browser to data / application ) to become an integration platform.
Today, most new applications are "Web ready" out of the box -- i. e. , designed to support a Web browser front end. Our claim is that future applications will also be "Web integration ready" out of the box -- that is, ready to plug into this emerging "backplane" of eXtensible Markup Language (XML) and Web services that will enable them to seamlessly interconnect with other Web-based applications. But XML and Web services only define the protocols -- that is, the standard wire formats that ensure interoperability.
How will the industry protect investment in the programming of the orchestration logic that ties Web applications together? Just as application programming standards like servlets, JavaServer Pages (JSP), and Active Server Pages (ASP) were crucial to the success of the Web, integration programming standards are essential to Web-based integration. In fact, most of the infrastructure standards necessary to enable such a "sea change" are already in place. As a result, the integration market, like that for Web application development before it, is poised for sweeping standardization. BEA has been collaborating with our platform competitors (primarily IBM and Microsoft) to remake the Web into an application development and integration platform -- Web 2. 0 if customer will.
Assuming some are successful (as industry analysts now predict), Web application servers (for Web application development and hosting) will be superceded by Web application platforms, which include tightly integrated portal, EAI, B 2 BI, and data integration technologies. Web 2. 0, then, may well have a bigger impact on enterprise IT than Web 1. 0 did. Middleware Infrastructure The foundation of all integration products (including the more traditional proprietary technologies as well as the emerging Web platform alternatives) is the middleware bus that provides interconnections and ensures quality of service. Historically, the industry has selected industry-standard middleware (either Java 2 Enterprise Edition/[J 2 EE] or.
NET-based) for developing and hosting Web applications, but proprietary middleware for integrating those applications. But the promise of Web 2. 0 is based on convergence to a single unified platform that does both. As a result, the standard Web application servers (WebLogic, WebSphere, . NET, etc. ) are displacing proprietary integration middleware: it turns out to be a lot easier to extend standard Web application servers to do integration than it is to remake proprietary integration brokers into Web-standard application servers. (Note: The fact that most of the historically proprietary integration vendors are now including application server technology within their next-generation integration solutions is more compelling evidence for this convergence. The challenge for those vendors, of course, is that this is the "home court" that the Web application platform leaders [BEA, IBM, Microsoft] staked out years ago. ) Web services and adapters link the Web integration platform to other applications and data sources. While the middleware layer is colored green (meaning that J 2 EE and.
NET are now safe bets), this layer is a mix of red and green since the essential Web services standards are still being fleshed out. It is clear within this core the technologies that Web Services Interoperability (WSI) validates in its basic profile. Today inter-container interoperability for Web services should likely be restricted to the WS-I basic profile of XML Schema, SOAP 1. 1, and WSDL 1. 1. By venturing outside the scope of what we vendors are ourselves testing, you are likely to encounter interoperability issues between different containers -- e. g. , between WebLogic and. NET.
Intra-container interoperability, however, should not be an issue for the newer Web service standards. An XML-based schema language, typically XML Schema, is the preferred choice for Web service payloads. If XML Schema is becoming a lingua franca for interoperable business objects, then the Simple Object Access Protocol (SOAP) is the framework of "comparable" message headers for defining ever higher qualities of service for passing those business objects between applications (e. g. , security, guaranteed delivery). With Web services, programmers should be careful not to "hardware" schemas to the business logic so as to achieve the looser coupling that made the Web so successful. Unfortunately, loose coupling is not inherent in Web services -- you must program for it. (Note: Loose coupling works on the Web in the sense that a Web site can undergo dramatic change [say a migration from.
NET to Java] without affecting the end users [who may not even notice ASPs turning into JSPs]. Web services loose-coupling is fundamentally harder to achieve. The Web client [browser] and schema [HTML] are fixed, while both sides of the Web services "wire" are expected to accommodate change independently. ) In particular, it is recommended that if you use Java as your Web services "design center" (that is, you auto generate Web Services Definition Language [WSDL] from Java classes), you should use "wrapper" classes rather than directly exporting application objects. Specialists also recommend that customers leverage the extensibility model of XML Schema, and use higher-level bindings like XML Query and "schema compilers" such as XML Beans, JAX-B, and JAX-RPC. Developers can thereby ensure that application changes will be less likely to break Web service interfaces and interface changes will be less likely to break applications. Above the basic profile defined by WS-I are specialists proposals for the standards that will complete the Web services core.
WS Security provides selective encryption (privacy), non repudiation, and support for delegation (propagation of security context). This emerging OASIS standard is poised to be the "SSL" of Web services. WS-Reliable Messaging (WS-RM) and WS-Addressing (from BEA, IBM, Microsoft, and others) ensure that message delivery can be transactional guaranteed across unreliable networks and systems. WS-RM and WS-Addressing use store and forward messaging to commodities into the Web services stack what has historically been the domain of proprietary message-oriented middleware like MQSeries. BEA remains convinced that such asynchronous Web services are the "sweet spot" for transactions/ updates, while synchronous Web services tend to be better suited to queries. This is why we have put so much energy into making asynchronous Web services as easy to program as synchronous ones.
ADAPTERS Adapters solve the "last mile" problem of integration: they provide the link from the Web technology to a non-Web or "legacy" technology (such as COBOL/CICS). By using the term "legacy, " I intend no insult: becoming part of the legacy is the highest goal that software can achieve, of course, many of them never make it, and in a very real sense, all production applications are legacy. Even with the emergence of XML and Web services, adapters remain essential because so little of today's legacy applications will be directly extended to support Web services. (Instead, legacy applications will be "wrapped" with Web services and new business logic deployed on containers like WebLogic, WebSphere, and. NET. ) Without a standard model for adapters, it's nearly impossible for an integration platform to get to critical mass. Consider the impact that standardizing a common database adapter -- Java Database Connection (JDBC) -- had on Java's success. The J 2 EE Connector Architecture (CA) generalizes JDBC to define a universal model for Java adapters.
J 2 EE CA (like the. NET alternative) eliminates the m x n cost of each integration vendor (m) having to "one off" their own proprietary adapter for each and every legacy system (n). Moreover, J 2 EE CA protects your programming investment in integration solutions just as JDBC protects investment in database applications. Transformation, Aggregation, and Mapping Inherent in our notion of Web 2. 0 is the expectation that XML becomes the inter application data representation. Despite the marketing hype to the contrary, XML does not itself resolve impedance mismatches between differing data representations, and we are witnessing the proliferation of XML Schemas across the enterprise. (Some large companies may already have more than a hundred schemas for "customer." ) XML simply defines a common alphabet for constructing documents (think "structured ASCII"); it is still up to the respective companies and industries to define the vocabularies (the semantic mapping from XML to business objects) that enable conversations to take place. Some of these vocabularies will be defined "top down" by industry standards bodies and consortia.
Other vocabularies will grow "bottom up" (much as natural languages have) as individual companies or small groups of companies specify the Web services necessary for conducting business with them. XML-based EAI faces the same challenges, albeit within a single company. Tools that map from one vocabulary to another dramatically ease this burden -- XML Query in particular is becoming the "SQL" of XML processing. But while XML transformation is getting easier and faster, you should nevertheless seek to constrain the explosion of XML Schemas by introducing a review / approval process by your business application architects. Programming The cost of integration solutions is still dominated by the cost of programming the glue code that ties the integration business process (workflows and Web flows) to the underlying business applications. Unfortunately, the state of the art still remains a long way from nirvana -- when a business analyst will define only the high level business process, and the infrastructure will "magically" generate the necessary glue code.
Historically, one of the biggest risks to integration projects has been their dependence on proprietary application programming interfaces (APIs) for programming this glue. With no standard APIs, there is no investment protection in integration programs or programmers. Nor are there the richer tools that follow from API standardization (such as those created for SQL and J 2 EE). Independent software vendors (ISVs) in particular are desperate to build integration solutions that can be deployed across multiple containers (e. g. , be portable to both WebLogic and WebSphere).
Of course, the Java and XML communities have been hard at work extending the Web application platform standards to protect investment in integration tasks. Some highlights worth a closer look: XML Query (W 3 C) Java Web Services (JWS) (JSR- 181) Process Definition for Java (JSR- 208) BPEL 4 WS (published by BEA, IBM, and Microsoft) Java Meta Data (JSR- 175) XML Beans (open source from BEA) Portlets (JSR- 168) Content Management Interface (JSR- 170) Apache Struts and Java Server Faces (JSR- 127) Web Services for Remote Portlets (WSRP; OASIS) Orchestration At the orchestration level, programmers include the declarative glue essential to integration: workflows, "Web flows, "work-lists" (collaborative document flow through an organization), and choreography -- abstracted message sequences that define how workflows can be composed within and even between companies. The most well understood technology at the orchestration level is Business Process Management (BPM). BPM refers to the graphical languages and tools for composing workflows -- computational sequences of tasks and exceptions. Most programmers are convinced that a variety of workflow representation languages will be required by the enterprise: Those targeted at the business analyst (e. g. , Aris) Those that are seamlessly integrated with Java (Process Definition for Java/JPD) Those that are programming language independent (BPEL 4 WS) For Java-based workflows, PDJ will remain the best fit.
BPEL 4 WS, however, provides a level of independence between the Java and. NET worlds, at the cost of introducing a new XML programming language. User should expect PDJ and BPEL to converge going forward -- PDJ will become the Java realization of a BPEL workflow Integration Brokering and Management While integration solutions still require coding, the goal remains to minimize that coding. Security is similar in this regard: historically, authorization was hand-coded into the application. Now the leading Web platforms define security policies administratively through business-oriented rules (that can be applied to a particular endpoint or across an entire application). The same shift is already underway for command and control -- the decision about how to route a particular request (say a trade) could depend upon the client (quality of service obligation), the content (dollar value), the receiver (which transform or adapter to apply), or the state of the infrastructure (availability, load).
If such logic is programmed into the application, then it cannot be changed without modifying and redeploying the business logic. By capturing such metadata administratively, change can be accommodated far more easily and economically. The integration platform's management environment must provide a comprehensive operational view into the interworking's of the integration broker and its connections to various applications. Looking forward, integration environments will have to become more self-optimizing and self-healing -- raising alerts to the human administrator only when the available resources are insufficient to meet the committed quality of service. Conclusion Addressing the complexity and cost of integration may well be IT's single biggest need. Unfortunately, there are no panaceas: integration is and will remain an inherently hard problem.
However, with Web 2. 0, the industry can still do dramatically better -- better by increasing investment protection and by cutting non inherent complexity. With a standard integration platform and the associated tools, the industry should be able to cut non inherent complexity by a factor of 10 -- making integration projects more predicable, more successful, and maybe even fun. Of course, Web 2. 0 is going to take time to mature. Web services standards, in particular, continue to evolve: interoperable end-to-end security and guaranteed delivery should appear later this year. So if the Web 2. 0 standards are not all in place just yet, does that mean organizations should wait? Hardly.
Products that represent the leading edge in Web- and Java-standard integration -- like WebLogic Integration, Portal, Liquid Data, and their direct competitors -- are feature / function competitive with the proprietary alternatives today, and in a dramatically better position to protect your long-term investment. How, then, should organizations best prepare themselves for Web 2. 0 -based integration? By treating integration challenges both tactically and strategically: tactically, by getting the job done with a mix of benefit standard and proprietary technologies; and strategically, by betting on the emerging Web 2. 0 integration platform. For those who still have doubts about integration converging around these standards, a little history: in 1997 specialists made a little-noticed prediction that an emerging mix of server-side Java standards (which later became J 2 EE) would have a profound impact on Web application development. At the time, there were some 30 -odd Web application server vendors, each promoting their own proprietary programming models and tools. Today, there is a multi-billion dollar market for J 2 EE-standard Web application servers led by BEA WebLogic and IBM WebSphere, and Microsoft has launched the.
NET Server family, at least partially in response to the popularity of J 2 EE. The smart money is on history repeating itself for Web-based integration. The compelling need for a more scalable approach to integration, for investment protection via standards, and for the ease-of-development tools that follow from standards will drive this convergence. As with all technology transformations, right now there are compelling opportunities to gain a competitive advantage, especially for independent software vendors and systems integrators focused on integration. Of course, there is also risk. Yes, risk in betting on technologies that are not fully baked, but also risk in throwing good money after bad by not recognizing an impending paradigm shift.
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