As promised, let me talk in more detail on the metaweblog API addition to this blog. This is very useful feature for me as my blog posting page is very basic (think of a text box that accept blog title, category drop down, and a blog entry multiline text box). Now, I can use third party clients to post the entries. Currently I am using Windows Live Writer to post the blogs. So what goes into implementing this API? It sits on top of XML-RPC protocol making it almost feel like a web service. XML-RPC messages are more leightweight, simpler. The .NET Framework doesn't implement XML-RPC client or server sides, so first I had to obtain the .net implementation for the protocol. It seems to me that the number one choice for this in .net world is http://www.xml-rpc.net/ provided libaries.
Next you have to implement and provide a service end point for the API implementation. Since I chose to implement the xml rpc request handler in the generic handler (ashx in asp.net), I added the handler to my project. This is where the metaweblog API gets implemented. Writing xml-rpc type class is pretty much the same as writing a web service. Just reference xmlrpc.net library and add xml-rpc methods (indicated by the attributes). Here is the implementation of metaWeblog.editPost RPC call:
public class metweblog : XmlRpcService
{
[XmlRpcMethod("metaWeblog.editPost")]
public string UpdatePost(string blogid,
string username,
string password,
XmlRpcStruct entry,
bool publish)
{
if (!Authenticate(username, password))
return null;
Entry e = Entries.GetEntry(Convert.ToInt32(blogid));
if (publish)
e.Active = true;
else
e.Active = false;
e.Body = entry["description"].ToString();
e.Title = entry["title"].ToString();
e.EditDate = DateTime.Now;
return e.Save().ToString();
}
}
Notice how the implementing class inherits from XmlRpcService (which provides all the plumbing code for the handler). The methods have XmlRpcMethod attribute. "metaWeblog.editPost" specifies what procedure in the API the method implements. One interesting construct in the whole XML-RPC protocol is the XmlRpcStruct. I think of it as a simple key-value collection allowing to pass many values to the methods.
Anyways, that's about it. Besides "metaWeblog.editpost" I also provide other metaWeblog API implementation methods:
[XmlRpcMethod("metaWeblog.newPost")]
public string NewPost(string blogid, string username, string password, XmlRpcStruct entry, bool publish)
[XmlRpcMethod("metaWeblog.getRecentPosts")]
public XmlRpcStruct[] GetRecentPosts(string blogid, string username, string password, int numberOfPosts)
[XmlRpcMethod("blogger.deletePost")]
public bool DeletePost(string appKey, string postid, string username, string password, bool publish)
[XmlRpcMethod("blogger.getUsersBlogs")]
public UserBlog[] getUsersBlogs(string appKey, string username, string password)
[XmlRpcMethod("metaWeblog.getCategories")]
public XmlRpcStruct[] getCategories(string blogid, string username, string password)
[XmlRpcMethod("metaWeblog.newMediaObject")]
public XmlRpcStruct NewMediaObject(string blogid, string username, string password, XmlRpcStruct rpcstruct)
The above shown 6 methods and the editPost method provides all that I needed to use Windows Live Writer to post the entries. I should look around for other clients and see how they work. In any case, it was a fun little coding exercise.
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