Re: [xwiki-dev] Proposal: XML-RPC API - True Interoperability with Confluence

Hello, We have decided to implement the Confluence Remote API because the interoperability would bring many advantages to XWiki (as Vincent explained here http://tinyurl.com/ypfamt). However at this moment the XWiki implementation of this API is not yet interoperable with Confluence. And this is not only because we are implementing only a very small subset of the API, but more important because nobody ever checked that we are in fact behaving similarly. The goal should be to write clients that are able to run against XWiki or Confluence servers without being able to tell any difference. At this moment this is not the case and there are many reasons for this. One reason is that we are currently relying on dynamic proxies in our client code (http://ws.apache.org/xmlrpc/advanced.html). In this setting the client and the server have to use the same Java interface, namely com.xpn.xwiki.xmlrpc.ConfluenceRpcInterface. And no, there is absolutely no chance to convince the Confluence team to implement this XWiki-specific interface. One way around this is to write client code which does not use dynamic proxies, but that is tedious and error prone (e.g. you can pass as many agruments as you like and you can call methods that don't exist). Remote calls look like this: token = (String)rpc.execute("confluence1.login", new Object[] {token, username, password}); There is however a better option, and that is to use swizzle-confluence, a client proxy for the confluence XML-RPC API (http://docs.codehaus.org/display/SWIZZLE). This would offer all the advantages of calling a typed proxy. Still all calls would eventually look like the one above, so they could go to any server that implements the interface (whether it's XWiki or Confluence). There are many other advantages: swizzle is intuitive, well-documented, well-tested and makes it unnecessary to explicitly pass a token around. Switching to swizzle would mean that all our client code would need to be modified. I already started to convert our tests to swizzle and it seems an easy task. Setup is a lot easier than before. Compare this: XmlRpcClientConfigImpl clientConfig = new XmlRpcClientConfigImpl(); clientConfig.setServerURL(new URL("http://127.0.0.1:8080/xwiki/ xmlrpc")); XmlRpcClient rpcClient = new XmlRpcClient(); rpcClient.setConfig(clientConfig); ClientFactory factory = new ClientFactory(rpcClient); xwikiRpc = (ConfluenceRpcInterface)factory.newInstance (ConfluenceRpcInterface.class); to this Confluence rpc = new Confluence("http://127.0.0.1:8080/xwiki/xmlrpc"); And using swizzle for the tests will allow not only to test the xwiki implementation, but to validate that we are testing the right behavior by running the tests against a confluence instance (this can be done once when designing the test, not all the time). Using swizzle is however not enough. Additionally we need to ensure that the observable behavior of XWiki matches that of Confluence. For example we will need to adjust the way we deal with page modifications and histories to the way Confluence does it. And we will need to mirror even strange behavior in Confluence. For example we will need to convert all non-string primitive values (e.g int, Date) into strings in the maps and lists that get exchanged between the client and server. Even if this is strange, this is how Confluence does it and this is how clients (like the ones using swizzle) expect their results. I'm already working on these modifications and if everybody agrees they will make it into the trunk after the M4 release. The easiest way to adapt clients to these changes will be to make them use swizzle. Regards, Catalin -- You receive this message as a subscriber of the xwiki- dev(a)objectweb.org mailing list. To unsubscribe: mailto:xwiki-dev-unsubscribe@objectweb.org For general help: mailto:sympa@objectweb.org?subject=help ObjectWeb mailing lists service home page: http://www.objectweb.org/ wws