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Stomp is a text-orientated wire protocol that allows Stomp clients to communicate with Stomp Brokers. HornetQ now supports Stomp 1.0, 1.1 and 1.2.
Stomp clients are available for several languages and platforms making it a good choice for interoperability.
HornetQ provides native support for Stomp. To be able to send and receive Stomp messages,
you must configure a NettyAcceptor with a protocol
parameter set to stomp:
<acceptor name="stomp-acceptor"> <factory-class>org.hornetq.core.remoting.impl.netty.NettyAcceptorFactory</factory-class> <param key="protocol" value="stomp"/> <param key="port" value="61613"/> </acceptor>
With this configuration, HornetQ will accept Stomp connections on
the port 61613 (which is the default port of the Stomp brokers).
See the stomp example which shows how to configure a HornetQ server with Stomp.
Message acknowledgements are not transactional. The ACK frame can not be part of a transaction
(it will be ignored if its transaction header is set).
HornetQ currently doesn't support virtual hosting, which means the 'host' header in CONNECT fram will be ignored.
HornetQ specifies a minimum value for both client and server heart-beat intervals. The minimum interval for both client and server heartbeats is 500 milliseconds. That means if a client sends a CONNECT frame with heartbeat values lower than 500, the server will defaults the value to 500 milliseconds regardless the values of the 'heart-beat' header in the frame.
Stomp clients deals with destinations when sending messages and subscribing. Destination names are simply strings which are mapped to some form of destination on the server - how the server translates these is left to the server implementation.
In HornetQ, these destinations are mapped to addresses and queues.
When a Stomp client sends a message (using a SEND frame), the specified destination is mapped
to an address.
When a Stomp client subscribes (or unsubscribes) for a destination (using a SUBSCRIBE
or UNSUBSCRIBE frame), the destination is mapped to a HornetQ queue.
Well behaved STOMP clients will always send a DISCONNECT frame before closing their connections. In this case the server will clear up any server side resources such as sessions and consumers synchronously. However if STOMP clients exit without sending a DISCONNECT frame or if they crash the server will have no way of knowing immediately whether the client is still alive or not. STOMP connections therefore default to a connection-ttl value of 1 minute (see chapter on connection-ttl for more information. This value can be overridden using connection-ttl-override.
If you need a specific connection-ttl for your stomp connections without affecting the connection-ttl-override setting, you can configure your stomp acceptor with the "connection-ttl" property, which is used to set the ttl for connections that are created from that acceptor. For example:
<acceptor name="stomp-acceptor"> <factory-class>org.hornetq.core.remoting.impl.netty.NettyAcceptorFactory</factory-class> <param key="protocol" value="stomp"/> <param key="port" value="61613"/> <param key="connection-ttl" value="20000"/> </acceptor>
The above configuration will make sure that any stomp connection that is created from that acceptor will have its connection-ttl set to 20 seconds.
Please note that the STOMP protocol version 1.0 does not contain any heartbeat frame. It is therefore the user's
responsibility to make sure data is sent within connection-ttl or the server will assume the client is dead and clean up server
side resources. With Stomp 1.1 users can use heart-beats to maintain the life cycle of stomp
connections.
As explained in Chapter 9, Mapping JMS Concepts to the Core API, JMS destinations are also mapped to HornetQ addresses and queues. If you want to use Stomp to send messages to JMS destinations, the Stomp destinations must follow the same convention:
send or subscribe to a JMS Queue by prepending the queue name by jms.queue..
For example, to send a message to the orders JMS Queue, the Stomp client must send the frame:
SEND destination:jms.queue.orders hello queue orders ^@
send or subscribe to a JMS Topic by prepending the topic name by jms.topic..
For example to subscribe to the stocks JMS Topic, the Stomp client must send the frame:
SUBSCRIBE destination:jms.topic.stocks ^@
Stomp is mainly a text-orientated protocol. To make it simpler to interoperate with JMS and HornetQ Core API,
our Stomp implementation checks for presence of the content-length header to decide how to map a Stomp message
to a JMS Message or a Core message.
If the Stomp message does not have a content-length header, it will be mapped to a JMS TextMessage
or a Core message with a single nullable SimpleString in the body buffer.
Alternatively, if the Stomp message has a content-length header,
it will be mapped to a JMS BytesMessage
or a Core message with a byte[] in the body buffer.
The same logic applies when mapping a JMS message or a Core message to Stomp. A Stomp client can check the presence
of the content-length header to determine the type of the message body (String or bytes).
When receiving Stomp messages via a JMS consumer or a QueueBrowser, the messages have
no properties like JMSMessageID by default. However this may bring some inconvenience to
clients who wants an ID for their purpose. HornetQ Stomp provides a parameter to enable
message ID on each incoming Stomp message. If you want each Stomp message to have a unique ID,
just set the stomp-enable-message-id to true. For example:
<acceptor name="stomp-acceptor"> <factory-class>org.hornetq.core.remoting.impl.netty.NettyAcceptorFactory</factory-class> <param key="protocol" value="stomp"/> <param key="port" value="61613"/> <param key="stomp-enable-message-id" value="true"/> </acceptor>
When the server starts with the above setting, each stomp message sent through this
acceptor will have an extra property added. The property key is
hq-message-id and the value is a String representation of a long type internal
message id prefixed with "STOMP", like:
hq-message-id : STOMP12345
If stomp-enable-message-id is not specified in the configuration, default
is false.
HornetQ also support Stomp over Web Sockets. Modern web browser which support Web Sockets can send and receive Stomp messages from HornetQ.
To enable Stomp over Web Sockets, you must configure a NettyAcceptor with a protocol
parameter set to stomp_ws:
<acceptor name="stomp-ws-acceptor"> <factory-class>org.hornetq.core.remoting.impl.netty.NettyAcceptorFactory</factory-class> <param key="protocol" value="stomp_ws"/> <param key="port" value="61614"/> </acceptor>
With this configuration, HornetQ will accept Stomp connections over Web Sockets on
the port 61614 with the URL path /stomp.
Web browser can then connect to ws://<server>:61614/stomp using a Web Socket to send and receive Stomp
messages.
A companion JavaScript library to ease client-side development is available from GitHub (please see its documentation for a complete description).
The stomp-websockets example shows how to configure HornetQ server to have web browsers and Java
applications exchanges messages on a JMS topic.
StompConnect is a server that can act as a Stomp broker and proxy the Stomp protocol to the standard JMS API. Consequently, using StompConnect it is possible to turn HornetQ into a Stomp Broker and use any of the available stomp clients. These include clients written in C, C++, c# and .net etc.
To run StompConnect first start the HornetQ server and make sure that it is using JNDI.
Stomp requires the file jndi.properties to be available on the
classpath. This should look something like:
java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory java.naming.provider.url=jnp://localhost:1099 java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces
Make sure this file is in the classpath along with the StompConnect jar and the
HornetQ jars and simply run java org.codehaus.stomp.jms.Main.