io.cdap.cdap.api.service.http

Class HttpContentConsumer

java.lang.Object

io.cdap.cdap.api.service.http.HttpContentConsumer

public abstract class HttpContentConsumer
extends Object

An instance of this class is for consuming an HTTP request body incrementally. Methods defined in HttpServiceHandler can return an instance of this class to consume the request body in small chunks, to avoid running out of memory for requests with a large body. Example:

      public class MyHttpHandler extends AbstractHttpServiceHandler {

         @POST
         @Path("/digest")
        public HttpContentConsumer computeDigest(HttpServiceRequest request,
                                                 HttpServiceResponder responder,
                                                  @HeaderParam String digestType) throws Exception {
          if (digestType == null) {
            responder.sendError(400, "No message digest type is provided");
            return null;
          }

          final MessageDigest messageDigest = MessageDigest.getInstance(digestType);
          return new HttpContentConsumer() {

             @Override
            public void onReceived(ByteBuffer chunk) throws Exception {
              messageDigest.update(chunk);
            }

             @Override
            public void onFinish(HttpServiceResponder responder) throws Exception {
              responder.sendString(Bytes.toHexString(messageDigest.digest()));
            }

             @Override
            public void onError(HttpServiceResponder responder, Throwable failureCause) {
              responder.sendError(500, failureCause.getMessage());
            }
          }
        }
      }
   

Constructor Summary

Constructors

Constructor and Description
HttpContentConsumer()

Method Summary

Modifier and Type	Method and Description
abstract void	onError(HttpServiceResponder responder, Throwable failureCause) This method is invoked when there is an error while processing the request body chunks.
abstract void	onFinish(HttpServiceResponder responder) This method is invoked when the end of the request body is reached.
abstract void	onReceived(ByteBuffer chunk, Transactional transactional) This method is invoked when a new chunk of the request body is available to be consumed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HttpContentConsumer

public HttpContentConsumer()

Method Detail

onReceived

public abstract void onReceived(ByteBuffer chunk,
                                Transactional transactional)
                         throws Exception

This method is invoked when a new chunk of the request body is available to be consumed. It is guaranteed that no concurrent calls to this method will be made.

Access to transactional Datasets must be through the Transactional.execute(TxRunnable) method.

Parameters:

chunk - a ByteBuffer containing a chunk of the request body

transactional - for executing a TxRunnable in a single transaction.

Throws:

Exception - if there is any error when processing the received chunk

onFinish

public abstract void onFinish(HttpServiceResponder responder)
                       throws Exception

This method is invoked when the end of the request body is reached. It must use the given HttpServiceResponder to send the response in order to complete the HTTP call. This method is always executed inside a single transaction unless annotated with TransactionPolicy(TransactionControl.

Parameters:

responder - a HttpServiceResponder for sending response

Throws:

Exception - if there is any error

onError

public abstract void onError(HttpServiceResponder responder,
                             Throwable failureCause)

This method is invoked when there is an error while processing the request body chunks. It must use the given HttpServiceResponder to send the response in order to complete the HTTP call.

Any issues related to network as well as any Exceptions raised from either onReceived(ByteBuffer, Transactional) or onFinish(HttpServiceResponder) methods will have this method invoked.

This method is always executed inside a single transaction unless annotated with TransactionPolicy(TransactionControl.

Parameters:

responder - a HttpServiceResponder for sending response

failureCause - the reason of the failure