CODEWITHSUNDEEP
activemq-classicstomp
Yakitawa
Yakitawa

Reputation: 169

ActiveMQ: Transforming OpenWire and STOMP messages

EDIT2: My issue here was caused by an insufficient understanding of how transport connectors work in ActiveMQ. TL;DR is that ActiveMQ will implicitly "transform" or "relay" messages between your transport connector configurations defined in activemq.xml.

EDIT: Additional info, the STOMP messages received by the Angular application are used for debugging and demo purposes. Hence, simply converting the OpenWire message to a blob of readable text is sufficient.

I'm creating an Angular application (preferably website, avoiding native applications), which objective is to "tap in" by web sockets on an ActiveMQ server and subscribe to OpenWire messages. How do I let ActiveMQ transform OpenWire messages to STOMP messages and send these to any clients (i.e. my Angular application) connected to the ActiveMQ WebSocket connector? In addtiion, it would be nice-to-have if I could transform STOMP to OpenWire as well.

In my understanding, what I am trying to do should be possible. It is noted by other users but not how. E.g. users hint that what I want is possible in ActiveMQ but not Apollo: ActiveMQ to Apollo transition, Openwire to Stomp protocol configuration.

I expect (preferably) the need to use something like an ActiveMQ transformer (e.g. adding transformer to the connector configuration: AMQP & Openwire - Activemq broker and 2 different consumers) or maybe writing an ActiveMQ plugin (http://activemq.apache.org/developing-plugins.html). On ActiveMQ's website, an existing transformer is mentioned (http://activemq.apache.org/stomp.html Message Transformations section):

Currently, ActiveMQ comes with a transformer that can transform XML/JSON text to Java objects

... but no mention of how to use this and I am unsure if I can benefit from this and if this means that there are no transformers for OpenWire-->STOMP or vice versa.

I expect I might have misunderstood some of the concepts, and a "you're going in a wrong direction, do this instead" can work out as a good answer for me. At the time of writing, I expect I will have to create an ActiveMQ plugin using their Message Transformer interface (http://activemq.apache.org/message-transformation.html) although their sub links are 404. I hope to achieve a more simple solution, e.g. an existing OpenWire-->STOMP transformer:

<transportConnector name="openwire" uri="{some-openwire-uri}?transport.transformer=stomp"/>

Upvotes: 2

Views: 1661

Answers (1)

Tim Bish
Tim Bish

Reputation: 18366

ActiveMQ will "transform" any Openwire message into a STOMP message and vice versa as needed based on client connections. I an Openwire based JMS client connects and places a message onto a queue and a STOMP based client comes along and subscribes to that queue the message will be converted into a STOMP message to send to that client.

Without knowing more about what issue you are having it is hard to provide more insight than that though. There are some cases where the transformation from Openwire to STOMP might not yield exactly the right thing for you such as a MapMessage or StreamMessage and definitely an ObjectMessage so some care needs to be taken about cross protocol messaging.

You do of course need to add a transport connector for each of the protocols you want to support, Openwire, STOMP, AMQP etc. The clients need something to connect to, then once they connect the broker manages the message transformations amongst subscriptions on Topics and Queues.

Upvotes: 2

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