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I have a requirement to implement an API using .NET technologies. The protocol is "plain old XML" (POX) over HTTP. There are 6 API calls, but all delivered from the same URI. The API method is identified by a "method" attribute in the top-level XML element. The child XML elements in the request and response depend on which method is being invoked.

For example:

<req method="GetStuff"><id>42</id></req>

might give response

<resp method="GetStuff"><Thing name="Bob"/></resp>

Or:

<req method="Status"><verbose>false</verbose></req>

might give response

<resp method="Status"><status>OK</status></resp>

I've considered WCF - I can see that following the example for a REST API I can easily get XML serialised and deserialised but cannot see an obvious way to get the method attribute to map to separate ServiceContract methods. I could also consider MVC but would need to mess about in the MVC pipeline somewhere to map the method to the appropriate Action.

Suggestions please?

MrBlueSky
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1 Answers1

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The method dispatch technique that you want (<req method='methodName'>) is a non-standard technique, so there is no built-in support for it. You have a couple of options:

1) Just do the dispatch yourself. E.g. if using WCF, have a single OperationContract method that looks at the attribute and then calls one of the 6 methods you need.

2) Create a custom dispatcher. For WCF, take a look at http://msdn.microsoft.com/en-us/library/ms734665%28v=vs.110%29.aspx . For ASP.NET Web API, you can probably start here - http://www.asp.net/web-api/overview/advanced/http-message-handlers - but I have less experience with it so can't tell you for sure.

Approach #1 is certainly much easier, but if you're going to create a lot of such APIs, #2 may be the way to go. Or just switch to something more standard - either SOAP, or a "true" RESTful API where all the routing/dispatch information is in the URL itself and not in the message body.

Eugene Osovetsky
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