Usage example:

    public class Person {
        public String name;
        public Integer age;
    }

    private Database db;
        
    public void onModuleLoad() {
        createDocument();
    }

    void createDocument() {
        db = new Database("test");
        
        Person p = new Person();
        p.name = "John";
        p.age = 31;
        db.save(p, new DoneCallback<Person>() {
            public void onFailure(Throwable exception) {}
            public void onSuccess(Person document) {
                editDocument(document);
            }
        });
    }
    
    private void editDocument(Person p) {
        p.age = 32;
        db.save(p, new DoneCallback<Person>() {
            public void onFailure(Throwable exception) {}
            public void onSuccess(Person document) {
                getDocument(document._id);
            }
        });
    }
        
    private void getDocument(String id) {
        Person p = new Person();
        p._id = id;
        db.get(p, new DoneCallback<Person>() {
            public void onFailure(Throwable exception) {}
            public void onSuccess(Person p) {
                getAll();
            }
        });             
    }

    private void getAll() {
        db.getAll(new Person(), new DoneCallback<List<Person>>() {
            public void onFailure(Throwable exception) {}
            public void onSuccess(List<Person> all) {
                for (Person p : all) {
                    delete(p);
                }
            }
        });
    }
        
    private void delete(Person p) {
        db.delete(p, new DoneCallback<Person>() {
            public void onFailure(Throwable exception) {}
            public void onSuccess(Person document) {}
        });
    }


How to try it:
Compile the example
$ cd example
$ mvn package

Create a document in CouchDB, and upload all files in target/gwt-couch-example-1.0-SNAPSHOT/gwt_couch_example/ as attachments.
Create the database named "test" that the example uses (database creation not supported yet).
If you attached the build output to a document named 'example' in a database named 'gwt-couch', you can now run the app by pointing your browser at something like http://localhost:5984/gwt-couch/example/example.html