Registers ReplicationReceiverWrapperFilter to the http service using Whiteboard

Replication Receiver Wrapper

This filter is to be installed on a AEM publish instance.
It will buffer the replication request responses until completion before sending back a success (200).
This will help AEM author to detect that the replication request has really succeeded which is really important in case of package replications.

ReplicationReceiverWrapperFilter.java

package daycare.core.filters;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Properties;
import org.apache.felix.scr.annotations.Property;
import org.apache.felix.scr.annotations.Service;
import org.osgi.framework.Constants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Component
@Service(value = Filter.class)
@Properties({ @Property(name = "pattern", value = "/bin/receive", propertyPrivate = true),
		@Property(name = Constants.SERVICE_RANKING, intValue = Integer.MAX_VALUE, propertyPrivate = true) })
public class ReplicationReceiverWrapperFilter implements Filter {

	private final Logger logger = LoggerFactory.getLogger(this.getClass());

	private final class BufferingResponse extends HttpServletResponseWrapper {

		private StringWriter writer;

		public BufferingResponse(final HttpServletResponse resp) {
			super(resp);
		}

		/**
		 * @see javax.servlet.ServletResponseWrapper#getWriter()
		 */
		@Override
		public PrintWriter getWriter() throws IOException {
			if (writer == null) {
				writer = new StringWriter();
			}
			return new PrintWriter(writer);
		}

		@Override
		public void resetBuffer() {
			if (this.writer != null) {
				this.writer = new StringWriter();
			}
			super.resetBuffer();
		}

		public void finish(ServletResponse response) throws IOException {
			if (writer != null) {
				response.getWriter().write(writer.toString());
			}
		}
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		final HttpServletRequest req = (HttpServletRequest) request;
		final HttpServletResponse res = (HttpServletResponse) response;

		logger.debug("1. Buffered Replication Receiver is called");
		final BufferingResponse bufResponse = new BufferingResponse(res);
		res.setStatus(500);
		chain.doFilter(req, bufResponse);
		res.setStatus(200);
		logger.debug("2. Buffered Replication Receiver is writing the response");
		bufResponse.finish(response);
		logger.debug("3. Buffered Replication Receiver has finished");
	}

	@Override
	public void destroy() {

	}
}