JMS is the bread and butter of the adapter; it’s been supported even since it was first released. We use JMS as the backbone of all our community deployments; we aren’t picky about the vendor, so long as it supports JMS 1.0 then the adapter will quite happily work with it. I’ve written previously about JMS Connections and the adapter. Most of time, it just works; the problems that you might be having will be configuration based because the default behaviour just aren’t suitable for your environment.
JMS Message Types and translation
All the standard JMS types are supported, BytesMessage, TextMessage, MapMessage, ObjectMessage are supported in the adapter via their associated MessageTypeTranslator implementations. Of course, vendor specific message types are also supported; such as Progress SonicMQ’s XMLMessage type. There’s also AutoConvertMessageTranslator which is primarily useful when configuring a consumer. By convention, we like you to know what type of message is being delivered onto the JMS destination that the adapter is receiving messages from; of course, sometimes there might be a mix of message types, or maybe you just don’t know. AutoConvertMessageTranslator automagically handles the standard types by delegating to the correct MessageTypeTranslator implementation so if it thinks the javax.jms.Message is a TextMessage then it will delegate to TextMessageTranslator. The mapping from MapMessage is quite simplistic: all name value pairs are assumed to be strings, and they are converted directly into metadata; the resulting payload is empty.
The JMS correlation ID is used, well for correlating things; typically a request with a reply message. If you need to handle the correlation id, then you need to configure a CorrelationIdSource implementation. The default is NullCorrelationIdSource which essentially ignores this JMS Header.
If the adapter is initiating a request and then waiting for a reply, then the JMSReplyTo header has a temporary destination associated with it. The expectation being that whatever is responding to the request will just use the JMSReplyTo header when replying to the request. Sometimes it doesn’t work, perhaps the back-end application doesn’t handle temporary destinations very well, or they don’t translate well into whatever underlying message system the JMS layer sits on tops of (back-end apps that use IBM MQSeries seem quite prone to this); in situations like this we need to specify a static reply to destination that already exists. Our JMS Producers can be told to not generate a temporary destination and to use a fixed JMSReplyTo destination by using the metadata key JMSAsyncStaticReplyTo; this will cause it to set whatever value stored against the metadata key as the JMSReplyTo header. This happens whenever the adapter produces a message to JMS, so it can be applied even if the workflow not trying to do a synchronous request reply (you might be making a request in one workflow, and having a different workflow handling the reply).
So if you wanted to force replies to a given message to come back on MyReplyToDestination then the configuration you need is something similar to this :
Conversely, if the adapter needs to reply to the JMSReplyTo Header, then within the same workflow, you can use JmsReplyToDestinationin the JMS Producer; this will cause it use JmsReplyTo header as the target destination.
JMSPrority, JMSDeliveryMode and JMSExpiration headers
By convention, the JMSPriority, JMSDeliveryMode, JMSExpiration are configured directly on the producer; time-to-live is configured on the producer, but this is used to derive the JMSExpiration header, as it is the exact time the message expires, but you pass how long the message is valid for at the point of the QueueSender.send() (blame the JMS API if you like). It is possible to control these headers dynamically on a per message basis by having per-message-properties on the producer set to true. If you are going to do that, then the following metadata keys come into effect.
- JMSPriority - this overrides the priority of the message. An integer value is acceptable here; any behaviour when you set the JMSPriority field is determined by the JMS vendor.
- JMSDeliveryMode - this overrides the the delivery mode of the message; it should either be the text “PERSISTENT”, “NON_PERSISTENT” or an integer value supported by the JMS vendor (for instance, 6 would be equivalent to NON_PERSISTENT_REPLICATED for SonicMQ).
- JMSExpiration - this will be used to generate the correct TTL when producing the message. The format of this value should either be a long value (similar to System.currentTimeMillis(), the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC); or a string value in the date format