io.cdap.cdap.api.service.http

Class HttpContentProducer

java.lang.Object

io.cdap.cdap.api.service.http.HttpContentProducer

public abstract class HttpContentProducer
extends Object

Instance of this class is for producing an HTTP response body in small chunks to avoid running out of memory when responding with a large body. An instance of this class can be provided to one of the send methods in HttpServiceResponder.

Constructor Summary

Constructors

Constructor and Description
HttpContentProducer()

Method Summary

Modifier and Type	Method and Description
long	getContentLength() Returns the length of the content or -1L if the length is unknown.
abstract ByteBuffer	nextChunk(Transactional transactional) This method provides a new chunk of data to be sent to the client.
abstract void	onError(Throwable failureCause) This method will get invoked when there is an error while sending body chunks.
abstract void	onFinish() This method will get invoked after the last chunk of data is sent.

Methods inherited from class java.lang.Object

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

Constructor Detail

HttpContentProducer

public HttpContentProducer()

Method Detail

getContentLength

public long getContentLength()

Returns the length of the content or -1L if the length is unknown.

nextChunk

public abstract ByteBuffer nextChunk(Transactional transactional)
                              throws Exception

This method provides a new chunk of data to be sent to the client. It is guaranteed that no concurrent calls to this method will be made. The implementation can reuse the same ByteBuffer instance across multiple calls to this method.

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

Parameters:

transactional - for executing a TxRunnable in a single transaction.

Returns:

a ByteBuffer containing the next chunk of bytes to be sent to the client. If the returned ByteBuffer is empty (Buffer.hasRemaining() == false), it signals that's the end of the response body.

Throws:

Exception - if there is any error

onFinish

public abstract void onFinish()
                       throws Exception

This method will get invoked after the last chunk of data is sent. It is always executed inside a single transaction unless annotated with TransactionPolicy(TransactionControl.

Throws:

Exception - if there is any error

onError

public abstract void onError(Throwable failureCause)

This method will get invoked when there is an error while sending body chunks. Any issues related to network as well as any Exceptions raised from either nextChunk(Transactional) or onFinish() methods will have this method invoked. This method is always executed inside a single transaction unless annotated with TransactionPolicy(TransactionControl.

Parameters:

failureCause - the reason of the failure