Better known in the i-technology world as enterprise application integration (EAI), B2B integration, or middleware, integration involves connecting internal systems with external business partners, customers, and suppliers. Integrating systems running on heterogeneous platforms, typically developed in different programming environments and managed by different groups (or different companies), is quite a complex task.

And guess what technology has been used to solve this complex problem? XML. Truly, the integration services space is probably the largest application area of XML. XML provides the world of integration with an open and extensible standard to define and implement loosely coupled business documents and processes.

To appreciate the value that XML brings to integration, I decided to talk with leading integration software providers who have used XML in various incarnations (a.k.a. markups) within their products and have extensively leveraged the benefits of XML.

Self-Describing Data Is the Key
Not surprisingly, there was a consensus among competitive vendors about what has been the biggest benefit of using XML in their core technologies. XML's success as the open-standard mechanism for self-describing data is most significant. The ability to carry metadata with data is particularly important in integration that involves sharing data within a heterogeneous environment where there isn't even a basic common element, such as data types. This "data-typing" information (XML Schemas) allows data to be efficiently routed and processed intelligently. This is a radically different approach to solving the integration problem - before XML, integration was all about connecting individual systems to each other, in most cases using a proprietary mechanism.

Toward Loosely Coupled Architectures
Another fundamental reason XML is important, which builds on the fact that it is self-describing, is that by using XML we're able to facilitate a document-centric, loosely coupled model for integration instead of the more tedious RPC/API-centric model. This model resembles in many ways how enterprises have functioned for years using a paper-based (document) model. This approach makes integration a lot easier to sell to businesses that conceptually agree with it. A natural extension of this loosely coupled architecture is really what the whole Web services phenomenon is about.

Web Services Orchestration - Silver Lining?
In a number of ways the emerging (or should I say already emerged?) Web services space has close ties to the world of integration. The core standards for Web services - XML, SOAP, and WSDL - are close to being "officially stamped," and lately there has been a lot of activity around establishing a standard mechanism for tying Web services together (a.k.a. orchestration of business processes). This is increasingly thought of as the missing link in the current integration and Web services technology infrastructures. Of course, this isn't an easy problem to solve; in addition, it's not an easy standard to get industry consensus on. Of course this is natural because there's inherent complexity as we move up the stack.

Isn't XML Verbose?
What about XML's being too verbose, which can in some cases lead to a performance hit? This is definitely a concern in some scenarios. Most vendors accept this fact; some consider it a serious problem and even suggest the need for a standard for compact/binary representation of XML. However, most don't consider a revolutionary change necessary. It's mainly evolutionary, and most of the vendors feel that, in line with Moore's law, growing processing power and improvements in parsers will solve this problem over time.

What About EDI?
It's true that EDI documents are still being utilized, and this will continue. The core benefit of EDI, however, is not the format but the fact that over the 20+ years during which EDI has evolved and been implemented by thousands of companies, it has established ubiquity in the business world. Much of the benefits of EDI lie in the fact that it's been used as the de facto format by numerous applications that have "built-in" support for the standard. Compared to EDI with its 20+ years of experience, XML is still a young child at 5 years old. XML does have technology advantages over EDI, but most of the integration players see EDI and XML as coexisting technologies, where EDI will continue to be used within established interfaces (applications/business partners) and XML will be gradually injected as the downstream integration mechanism. The presence of EDI systems was compared to the existence of the mainframe. Mainframe-based systems aren't going away, and neither is EDI. What started as coexistence will, however, gradually move toward replacement, as we have consensus in required transaction management, security, and quality of service infrastructure and standards. In addition, XML/Web services solutions will gradually emerge as much more financially optimal.

Common Business Markup - Not Yet a Reality
In XML's early years in the world of integration, we saw a number of industry initiatives that attempted to standardize common business documents within a particular domain. Some of these initiatives have reaped benefits, while others weren't able to harvest enough interest. However, apart from these industry-specific vocabularies, we've seen initiatives in action that attempted to create a cross-domain standard for business documents and in some cases even business processes - similar in a sense to what EDI has accomplished in the supply-chain world. In this area, most of the vendors feel that we're probably better off working on industry-specific standardization initiatives such as RosettaNet, CIDX, HIPAA, HL7, OFX, SWIFT, etc. Consensus on a standard for horizontally applied common business documents and processes is quite far away.

Vittorio Viarengo
Director of Product Management,
BEA Systems, Inc.
XML is the key technology that is enabling a whole new way of integrating applications and systems: loosely coupled integration. XML, and related standards such as XSchema, XSLT, and XQuery are bringing the cost of integration down by providing enterprises with a set of standards-based technologies to describe, query, and transform data. This makes it possible to tackle integration challenges that before XML were either too costly (proprietary technology, lack of skills) or not feasible (B2B integration over the Internet). Moreover XML's extensibility makes it easier to accommodate changes driven by ever-evolving business requirements and to integrate any type of data sources from structured (databases) to semi-structured data (content).

Tommy Joseph
CTO,
TIBCO Software Inc.
XML and related standards provide a standards-based expression for several of the concepts that lie at the core of the integration problem. For example, TIBCO pioneered the use of self-describing data for application integration. This concept lies at the heart of the XML standard. Other examples include the concepts of data transformation and service-oriented architectures. These concepts are expressed through the XSLT and WSDL standards, respectively. As these standards have gained acceptance, TIBCO has made them increasingly central to its strategy.ŠThe advantage of standardization is that it makes it easier for more and more services to be plugged into TIBCO's integration platform.Š On the other hand, integration is by definition a heterogeneous problem. The real world is composed of heterogeneous systems. So TIBCO's platform also includes support for other standards like J2EE, Microsoft's .NET and COM, CORBA, and a wide variety of legacy and proprietary technologies.

Dave Wascha
Lead Product Manager,
E-Business Servers,
Microsoft Corporation
The key value of XML is that its self-describing nature helps simplify integration. It might not be the best technically, but it has a lot of industry consensus. XML is still a relatively young technology. What we have seen so far is only 2-3 years of credible usage. We have a long way to go and we still have much to realize in tangible benefitsŠ. With the core standards around XML/Web services - SOAP/WSDL/UDDI being broadly agreed on - and the next set layer of standards in the stack close to being finished, we are about to hit the acceleration point of adoption. New technologies and products will be key in making the barrier to entry low. Even mom-and-pop shops, which form 80% of the global supply chain, need these technologies to be efficient, and they don't have much money to spend. We need real products that solve real business problems in a cost-effective way.

John Magee
Vice President,
Oracle9i Middleware and Tools,
Oracle Corporation
XML has become the key foundational technology for integration. Its powerful descriptive capabilities, combined with its relative simplicity, make it an ideal tool for addressing a wide variety of integration challenges. From data and application integration to distributed computing and Web services, XML has provided a means to codify and standardize interfaces that is driving a new level of software interoperability. As core standards such as Schema, XSLT, and XPath continue to solidify, and as emerging standards for Web services security, orchestration, reliability, and adapter-based integration architectures mature, XML-based middleware will provide a platform for automating business processes that span system and organizational boundaries.

Dale Skeen,
CTO,
Vitria Technology, Inc.
Adopting XML inside and outside the firewall makes some of the lower-level integration problems typically associated with data formats go away. This adoption is forcing companies to acknowledge and confront the harder problems in integration: What are my business semantics? How do I orchestrate with my business partners?ŠEmerging XML technologies, particularly around Web services, are definitely becoming pervasive, despite the existence of certain technical issues, especially around security and reliability. The real problem going forward lies not with these technical issues, which have known solutions, but with getting consensus and political buy-in for a single solution to each issue.

Eric Newcomer
CTO,
IONA Technologies
Wide adoption of XML-based standards such as Web services could eliminate historical barriers to interoperability and drastically reduce the price of integration - and speed time-to-market through rapid application assembly. Because the standards process is currently controlled by the software manufacturers and not the customers, however, it's very possible that progress toward reaching this goal will be slow rather than quick, since the manufacturers naturally protect established practices and business models. Industries tend to reap the benefits of standardization only when the consumers insist upon them, and this has yet to be the case for Web services. An open, end user-driven standards process will soon become a necessity to ensure that the industry progresses rapidly to produce the standards-based integration solutions that companies are demanding.

Rachel Helm
Director, Product Management,
WebSphere Business Integration,
IBM Corporation
Many IBM customers have chosen to revitalize their EDI solutions rather then completely replace them. Why? Because they've got tremendous investment in the semantic content of those EDI transaction formats they defined with their partners. Why abandon those partner agreement formats while they are still applicable? The VANs, on the other hand, are increasingly not cost-effective. So our customers move their existing EDI transactions over to an EDI/INT platform in order to have the best of both worlds: leveraging of still-relevant transaction document formats along with the cheap, pervasive technology of the Internet. What technology do they use as the data format bridge? You guessed it - XML.

Jim Green
CTO,
webMethods, Inc.
In the pre-1995 era in middleware, before EAI became a topic, the middleware space consisted of middleware products that view data as a BLOB, and we didn't have any ability to carry structure with the data. Both the sending and receiving applications knew about the proprietary structure, but there wasn't any easy way for a third-party application to know what was going on. XML truly emerged as an unambiguous standard to represent structure with the data. Including structure with the data provides a schema representation to the middleware that is fundamental to the technology and its ability to route data based on the type. XML was required to enable today's integration technologies.

David Litwack
Senior VP, Web Application
Development Products,
Novell, Inc.
XML is key to developing today's services-oriented applications. These are composite applications that pull information from a variety of existing and new data sources and transform them into business uses for which they were never originally intended. Going forward, an ever-increasing percentage of information that flows across networks will be XML-based. To date, the industry has been largely focused on the creation or production of Web services, but in the next several months I think we'll see increased focus on the consumption of services. For example, emerging standards like XForms will enable data binding of XML to presentation, thereby providing end-to-end production and delivery of services. This is where it starts to get interesting, as these new technologies empower a broader range of developers to quickly build services-oriented applications.

Conclusion
XML has truly emerged as one of the most significant technologies changing the landscape of technology itself. What was conceived as simple markup language has evolved as a ubiquitous data model for almost anything. XML is still, however, five years young. We have yet to realize the benefits of XML and its applications, particularly Web services. With the core infrastructure around XML, Schemas, and Web services laid out, XML adoption is about to take off.