Performance Test Web Services
If we look into the unique characteristics of Web Service performance two aspect stands out; on the server side there’s quite a bit of XML/JSON processing going on, both XML/JSON parsing and serialization, and the thing that often fails first is the processing of the payloads. The reasons why this fails can be multifold; it can be in the platform in the shape of for example weaknesses in the application server, and in the implementation in the shape of unnecessarily complex WSDL’s. It could also be that the code is making a request to a database that is slow in responding.
The complexity of parsing the XML/JSON payloads means that we have to put an extra focus on Scalability Testing, while the issue of security means we will have to focus some extra on doing testing of requests that are secure. If the entire Web Service is secure this means Load Testing is more important especially if WS-Security and token handling is used.
It also means we have to examine the WSDL’s closely. If the requests and responses are either complex or larger, or if they include large attachments, we have to focus on emphasizing that complexity and see how it behaves under load.