COMMENTARY --
The promise of Web services and services-oriented architecture (SOA) is interoperability among disparate software components, regardless of platform. It's the next software development nirvana, which is at the beginning of its ascendancy--meaning that there is lot of room for new companies to pave the way to the future.
I met with one of those companies, San Mateo, CA-based startup Brixlogic, which has developed a development tool for creating Web services based on XML schemas. XML schemas provide a way to define the structure, content and semantics of XML documents for a particular industry or set of tasks. For example, the Interactive Financial eXchange (IFX) schema was developed in collaboration with the financial industry as a way to express, in XML, standards for electronic bill presentment and payment, business-to-business payments, , business-to-business banking and ATM communications, as well as consumer-to-business and banking payments. It sets up relationships for performing processes among the various entities involved in financial transactions, such as debiting an account prior to an ATM withdrawal. Similarly, the ACORD Life Data Model defines a structured way of sharing complex insurance information to all parties involved in the industry.
However, working with Web services and XML schemas can be a difficult and produce unreliable results. Brixlogic claims that its software overcomes much of the complexity and unreliability in developing Web services derived from custom or industry standard XML schemas.
Brixlogic's XML Services Builder takes a high-level, 4GL (fourth-generation language, such as XML, BPML, XSLT, BPEL and XQuery) approach to building Web services. It uses a visual programming model to hide the complexity and a native XML processor language to create Web services that are correct by design. Using a native XML language rather than more traditional languages has some advantages. (Brixlogic does use Java as its deployment engine, and is developing runtimes for C++, C# and possibly SAP's ABAP.) Coding the application logic in Java or C#, for example, and then service-enabling it by generating Web service-related code using a Web services toolkit can result in interoperability and reusability problems.
According to Guillaume LeBleu, co-founder and CTO of Brixlogic, "Each programming language has its own type system, and each platform comes with multiple custom complex types [e.g., J2EE, .NET], which facilitate the creation of programs. In the same fashion, the XML schema language has its own XML typing system. While for simple primitive types, mapping the Java or C# type system to the XML schema type system is easy, it is not in most cases, such as for a vector or a data set. This mismatch has led to largely non-standardized XML representations of those types, called encodings. As a result, while the XML schema instance describing the service seems to describe an XML element, what is actually presented is a (.NET+XML) service or a (Java +XML) service--a hybrid containing information that ties the service to its originating platform, which can create costly interoperability issues."
Even using WSDL or a schema as the starting point can lead to problems. The type-checking associated with each pre-XML language still cannot verify compliance with the Web Service description at implementation times, resulting in expensive testing procedures, LeBleu said.
Brixlogic's guided development methodology enables validation of schemas based on service definitions and enforces compliance at implementation time. If the schema changes, the software track dependencies and show all services that are impacted by changes, LeBleu said. For example, after each operation in each branch of a schema, the XML types that were modified or newly created are computed to ensure that all of the output's constraints defined in the XML schema or WSDL are satisfied.
"Our language directly leverages the constraints [the characteristics of a type] enabled by XML schema," LeBleu said. "For example, in a schema like IFX, you can express how many times a field is optional or not. When you compile to Java or C#, there isn't a way to specify if the field is optional, so you lose the constraints. Because we are native XML, we keep the constraints and use them to drive the process and validate whether the field is compliant with the schema," LeBleu said.
The model-driven, iterative development environment hides much of the complexity--business people who have the domain expertise around the business process can work with the visual tools.
Brixlogic integrated modules include Studio, which is used to visually create XML-based scenarios designs and validate them. The Brixlogic Testing Module and Debugger is used to test sample input and outputs and debug live scenarios, including remotely. The Brixlogic Runtime supports BEA Weblogic, IBM WebSphere and Tomcat on Windows, Linux, Solaris, AIX and any runtime environment using the Brixlogic Runtime API. Current Brixlogic customers include NCR, Diebold, Verisign and Banco Popular in Puerto Rico.
You can write to me at dan.farber@cnet.com. If you're looking for my commentaries on other IT topics, check out my blog Between the Lines.
