21.3. Streaming large messages

HornetQ supports setting the body of messages using input and output streams (java.lang.io).
These streams are then used directly for sending (input streams) and receiving (output streams) messages.
When receiving messages there are two ways to deal with the output stream; you may choose to block while the output stream is recovered using the method ClientMessage.saveOutputStream or alternatively using the method ClientMessage.setOutputstream which will asynchronously write the message to the stream. If you choose the latter the consumer must be kept alive until the message has been fully received.
You can use any kind of stream you like. The most common use case is to send files stored on your disk, but you could also send things such as:
  • JDBC Blobs
  • SocketInputStream
  • Things recovered from HTTPRequests, and so on.
Anything that implements java.io.InputStream for sending messages, or java.io.OutputStream for receiving them can be used.

21.3.1. Streaming over Core API

The following table shows a list of methods available at ClientMessage which are also available through JMS by the use of object properties.

Table 21.1. org.hornetq.api.core.client.ClientMessage API

Name Description JMS Equivalent Property
setBodyInputStream (InputStream) Set the InputStream used to read a message body when sending it. JMS_HQ_InputStream
setOutputStream (OutputStream) Set the OutputStream that will receive the body of a message. This method does not block. JMS_HQ_OutputStream
saveToOutputStream (OutputStream) Save the body of the message to the OutputStream. It will block until the entire content is transferred to the OutputStream. JMS_HQ_SaveStream
To set the output stream when receiving a core message: 
...
ClientMessage msg = consumer.receive(...);

// This will block here until the stream was transferred
msg.saveToOutputStream(someOutputStream); 

ClientMessage msg2 = consumer.receive(...);

// This will not wait the transfer to finish
msg.setOutputStream(someOtherOutputStream); 
...
Set the input stream when sending a core message: 
...
ClientMessage msg = session.createMessage();
msg.setInputStream(dataInputStream);
...