Marc recently published a short
tutorial on how to use Apache Abdera with Apache
Abdera with our reference implementation of JAX-RS, Jersey. His code is server side, i.e.
it explains using Jersey and Abdera for creating RESTful web services with
Atom payload[1]. In this article I will give an example on how the
Jersey client API can be used to consume such a service with realitve ease.
It is hopefully known that Jersey contains a very simple, yet effective
HTTP client API. Core to it is the heavy use of the builder pattern for
creating and configuring requests. For our example, I start with creating the
client:
Client c = Client.create();
WebResource r = c.resource(new URI(someLocation));
We can now get the InputStream from the WebResource to read the Atom feed
into an Abdera Feed:
InputStream is = (InputStream) r.get(InputStream.class);
Document<Feed> doc = Abdera.getNewParser().parse(is);
Feed feed = doc.getRoot();
for (Entry entry : feed.getEntries()) {
doSomething(entry);
}
Now let’s say we want to post an entry to the resource in Marc’s article.
In this case we would also have to use his AbderaSupport class, which
implementes the proper MessageBodyReader
and MessageBodyWriter
interfaces for the Abdera objects. On the server side providing these
interfaces is enough, but on the client side we need to configure the Jersey
client. The following code helps doing this:
public static class AbderaClientConfig extends DefaultClientConfig {
@Override
public Set<Class<?>> getProviderClasses() {
Set<Class<?>> classes = new HashSet<Class<?>>();
classes.add(AbderaSupport.class);
return classes;
}
}
Thus completing our sample app:
ClientConfig cf = new AbderaClientConfig();
Client c = Client.create(cf);
WebResource r = c.resource(new URI(someLocation));
Entry entry = AbderaSupport.getAbdera().newEntry();
entry.setTitle(...);
entry.setContent(...);
ClientResponse cr = r.type(MediaType.APPLICATION_XML).put(ClientResponse.class, entry);
Done.
tags: Jersey Apache Abdera Atom JAX-RS
[1] Tim pointed
out that this style should properly called “AtomPub”, and not APP,
AtomPub/Sub or similar.