Sunday, November 13, 2011

Integrating Spring.NET with ASMX WebServices

In one of the previous post, we saw how easily we can Enable Dependency Injection for Web Forms Web Pages and User Controls.  In this post we will cover the last topic in the Dependency Injection series i.e. Enabling Dependency injection in ASMX WebServices using Spring.NET.

Its not at all difficult to Enable Dependency Injection in ASMX WebServices.  Lets look at the steps we will need to it
  • Configure the Spring Context in web.config
  • Add the Spring WebSupportModule Module to the list of httpModules
  • Configure the WebServiceHandlerFactory to intercept any path that matches the pattern *.asmx
  • Configure the WebService class in spring config file with its dependencies
Let's look at each step in a little more detail.

Step - 1 - Configure the spring context in web.config

First we need to add spring config section handler in the configSections.  The updated web.config looks like
Next we need to add the spring config section in web.config. This section will inform Spring.NET as to where should it look for its configuration file. Add the following section to web.config
Nothing special about the above piece of configuration. We are informing Spring.NET that its configuration file is located in ~/Config/ directory and its called webservice.xml.

Step - 2 - We need to add the Spring WebSupportModule module to the list of httpModules

In this step, we will need to add the WebSupportModule to the list of httpModules in the web.config.  This is how the updated web.config looks like
Step - 3 - Configure the WebServiceHandlerFactory to intercept any path that matches the pattern *.asmx

Again, all we need to do here is add an Handler in the httpHandlers section in web.config. Update web.config looks like
Step - 4 - Configure the WebService class in spring config file with its dependencies

We are almost there. All that is left now is to configure the WebService class in the Spring.NET configuration file webservice.xml.

Let's say that we want to develop a HelloWorld webservice, that has one method called GreetUser.  This method takes in the user name as argument.  We will inject the greeting to be used using Spring.NET.

The code of the HelloWorld webservice looks like

Nothing to explain here, all we are doing is prepending the Greeting Property to the userName passed and returning the value as the result.

Notice that this HelloWorldService class is a POCO and there is nothing web service specific to it.

The spring configuration that will inject the Greeting into the HelloWorldService looks like
Notice that, we are configuring the implementation of WebService with the ID HelloWorldServiceImpl.  However, the actual WebService is exposed via Spring.NET.  The Spring.Web.Services.WebServiceExporter acts as a proxy over the actual WebService implementation.

All set!

Lets run the server and browser the URL which would look like http://localhost:<your-port-number>/HelloWorldService.asmx?op=GreetUser.  This should open up a page which looks like this
Page which will let us invoke the HelloWroldService.GreeUser WebService
This is the page from which we could invoke the HelloWorldService.GreetUser WebService.

Let's type in Git Shah in the user name field and click Invoke.  Here is what we get
As you can see, the greeting message Good Morning was injected in the HelloWorldServiceImpl class via Spring.NET.

That's all folks, we have successfully Integrated Spring.NET with ASMX WebServices!

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