Currently there is no support for compression in the activemq http transport. It seems like a sensible enhancement. Please raise a jira issue to track this.

Connection configuration URI, follow-up question: How do I tell which protocols implement the useCompression property? For example does nio: implement useCompression="true"?

There was actually an issue recently fixed that was causing the TextMessage objects to not honor the ActiveMQConnectionFactory useCompression option, it was  AMQ-3556 you will find that if you use a recent 5.6 SNAPSHOT build that your sent TextMessages will arrive with the compressed option set to true. 

The compression that is done when the ActiveMQConnectionFactory useCompression option is enabled affects the Message body only and is not dependent on the transport so it should work over Http, TCP, SSL, or NIO without issue.

I agree that the property is on the connection and only the body/payload is compressed. Hence, it should apply for all protocols/transports and message types. 

However,

"Currently there is no support for compression in the activemq http transport. It seems like a sensible enhancement. Please raise a jira issue to track this." - gtully  above.

Gary's quote is essentially correct, the HTTP transport in 5.5 has no support for additional compression beyond what is already done in the code elsewhere, however it should allow the already compressed Message's to pass through with compression intact, which it will do for all Messages with the fix in the issue I referenced above.  The fact that the TextMessage was not getting its contents compressed was a bug which is fixed in 5.6.

I just completed  AMQ-3566  today which allows you to enable HTTP compression using gzip for the entire HTTP payload in the HttpTransport.

Thanks for the clarification.