My team at work recently encountered an interesting problem that required us to configure an Apache XML-RPC client to use a web-proxy when communicating with a server. In most corporate environments, the internal network sits behind a firewall and filtering web-proxy. If your XML-RPC client needs to communicate with a server outside of the firewall, the only way out is through a web-proxy that supports XML-RPC. After talking with several colleagues, I found that this seemingly simple need isn't very well documented. So this post is an attempt to somewhat officially document how to use a web-proxy with Apache's XML-RPC Java implementation. Surprisingly, it's actually quite simple once you've put the pieces together correctly.
If you're not familiar with XML-RPC, you can read up on it here.
Continue reading for the HOWTO.
If you're not familiar with XML-RPC, you can read up on it here.
Continue reading for the HOWTO.
The solution involves using an Apache Common's HttpClient with an XmlRpcCommonsTransportFactory. In a nutshell, it's a matter of configuring your XML-RPC transport factory to use an Apache Common's HttpClient with the web-proxy set accordingly.
Step 1, set the XML-RPC server URL in an XmlRpcClientConfigImpl object. Step 2, create a new XmlRpcClient object, and set the XmlRpcClientConfigImpl as its config. Step 3, create a new XmlRpcCommonsTransportFactory and a new HttpClient. Step 4, set the proxy you wish to use with the HttpClient using the setProxyHost() or setProxy() methods. Step 5, call setHttpClient() on the transport factory to set the HTTP client to the one you just created with the proxy configuration. Step 6, set the transport factory on the XmlRpcClient using setTransportFactory().
Here's some sample code ...
That's it!
Step 1, set the XML-RPC server URL in an XmlRpcClientConfigImpl object. Step 2, create a new XmlRpcClient object, and set the XmlRpcClientConfigImpl as its config. Step 3, create a new XmlRpcCommonsTransportFactory and a new HttpClient. Step 4, set the proxy you wish to use with the HttpClient using the setProxyHost() or setProxy() methods. Step 5, call setHttpClient() on the transport factory to set the HTTP client to the one you just created with the proxy configuration. Step 6, set the transport factory on the XmlRpcClient using setTransportFactory().
Here's some sample code ...
XmlRpcClientConfigImpl config = new XmlRpcClientConfigImpl();
config.setServerURL( serverURL );
client = new XmlRpcClient();
client.setConfig( config );
XmlRpcCommonsTransportFactory transportFactory
= new XmlRpcCommonsTransportFactory( client );
HttpClient httpClient = new HttpClient();
HostConfiguration hostConfiguration = httpClient.getHostConfiguration();
hostConfiguration.setProxy( "proxy.example.com", 8088 );
hostConfiguration.setHost( serviceURL );
transportFactory.setHttpClient( httpClient );
client.setTransportFactory( transportFactory );
That's it!
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