StreamWriter and ResponseContext

[James M Snell]

All,

General FYI...

The new StreamWriter interface provides significantly better performance
 when writing out documents than the object model.  To give you an idea
of the improvement, in my testing I was able to create 100 feeds with
5000 entries each in around 500ms.

When implementing an Atompub server, a significant performance
improvement can be realized by implementing a custom ResponseContext
implementation that takes pojo's and writes them out using StreamWriter
instead of building up an object model and using the
BaseResponseContext.  Below is a simple example of a custom
ResponseContext using StreamWriter:

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;

import org.apache.abdera.Abdera;
import org.apache.abdera.protocol.server.impl.AbstractResponseContext;

public class MyObjectResponseContext
  extends AbstractResponseContext {

  private final Abdera abdera;
  private final Foo foo;

  public MyObjectResponseContext(Abdera abdera, Foo foo, int status) {
    this.abdera = abdera;
    this.foo = foo;
    setStatus(status);
  }

  public boolean hasEntity() {
    return foo != null;
  }

  public void writeTo(
    OutputStream out)
      throws IOException {
    writeTo(new OutputStreamWriter(out,"UTF-8"));
  }

  public void writeTo(
    Writer javaWriter)
      throws IOException {
    if (hasEntity()) {
    abdera.newStreamWriter()
      .setWriter(javaWriter)
      .startElement("foo")
        .startElement("a")
          .writeElementText(foo.a)
        .endElement()
        .startElement("b")
          .writeElementText(String.valueOf(foo.b))
        .endElement()
      .endElement()
      .flush();
    }
  }

  public void writeTo(
    OutputStream out,
    org.apache.abdera.writer.Writer writer)
      throws IOException {
    throw new UnsupportedOperationException();
  }

  public void writeTo(
    Writer javaWriter,
    org.apache.abdera.writer.Writer abderaWriter)
      throws IOException {
    throw new UnsupportedOperationException();
  }

}

- James