SOA Web Services - Guidelines for Creating Interoperable Web Services

Guidelines for Creating Interoperable Web Services

Fundamentally, web services are interoperable. Thus, regardless of the client's hardware and software, it should be able to run a web service. The functionality of the web service should remain independent of the following:

• Application platform such as Weblogic server, SunOne App Server, .NET Server, and so on
• Programming language such as Java, C++, C#, Visual Basic
• Hardware such as PC, PDA, Mainframes
• Operating systems such as Unix, Linux, Windows, and so on
• Application data models

However, we have seen previously that due to differing implementations of the specifications by different vendors, some web services may not correctly interoperate with others. To create interoperable web services the following tips may be useful.

Avoid using Vendor-Specific Extensions

Some vendors may extend certain specifications such as SOAP and WSDL. Avoid using such extensions in your applications.

Use the Latest Interoperability Tests

WS-I publishes the tools for interoperability tests. Use the latest version of these tools while testing for interoperability. This will ensure the BP conformance of your web services.

Understand Application Data Models

When you integrate two applications, it is most likely these two applications will be using different data models though they may be providing similar functionality such as accounting. Understand carefully the data models of the two interacting applications and reconcile them in a common model.

Understand Interoperability of Data Types

All the data types of the two interacting applications may not be compatible to each other. Thus, when you pass parameters and receive the resulting values from a method call, if these data types are not compatible, the two applications will not interoperate correctly.

Having considered the various aspects of implementing SOA, the requirements for creating interoperable web services and various standards for interoperability, we will now take a practical approach to learning by demonstrating the creation of interoperable .NET and J2EE web services in the next section.