Handle and raise exceptions from Web services

Easy SOAP Web Services: Since Web services provide a platform-independent way of leveraging a specific functionality, the exceptions that occur in Web services must also be communicated in a platform-independent manner. To accomplish this communication, it must be compliant with the SOAP specification.

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by Thiru Thangarathinam, Intel Corp.

An exception is any error condition or unexpected behavior encountered by an executing program. Exceptions can occur for a number of reasons, such as faulty code, unavailable operating system resources, unexpected Common Language Runtime conditions, and so on. While your application can recover from some of these conditions, most runtime exceptions are irrecoverable. In that case, you need an effective way of handling the exception.

Web services are a relatively new form of distributed computing. In distributed computing, applications are designed as services that run on a server. Clients access these services through a programmable interface. When there is an exception during the execution of a Web service, the exception not only needs to be captured, but it also must be communicated back to the consumers of the Web service.

Since Web services provide a platform-independent of way of leveraging a specific functionality, the exceptions that occur in Web services must also be communicated in a platform-independent manner. To accomplish this communication, it must be compliant with the SOAP specification.

.NET Provides Robust Structured Exceptions Handling
The crux of the exception handling support in a .NET Web service is provided by the try Catch finally construction. The try keyword precedes a block of normal processing code that may throw an exception. The catch keyword precedes a block of exception-handling code. The finally keyword precedes a block of code that will always be executed after handling the exceptions. Once an exception is thrown from a try block, the program flow switches to the first catch block following it.

A well-designed set of error-handling code blocks can go a long way in making a program more robust and less prone to crashing. The best practices for handling exceptions can be summarized as follows: