The public API for XTS 1.1 is all that you need. It is located in the service archive file jbossxts.sar which is the released build product for XTS. Unofrtunately, this build product was not integrated into the AS release process under 5.0.0.GA (this has now been fixed for upcoming AS releases).
So, to obtain an XTS release you need to build jbossxts.sar youself. Youc an do this by checking out a JBossTS release and building first the JTA and then XTS.
You should check out the latest tagged JBossTS release which is 4.6.0.CR1.
Set JBOSS_HOME to point to the root fo your AS build (the directory containing common, server, etc).
In the root of your JBossTS checkout type
Then cd to the XTS subdirectory and type
ant clean install
You should find the relevant build products in XTS.xts-install
Note that the api jar is also embedded within the sar file.
Drop the sar file in $JBOSS_HOME/server//deploy to deploy the XTS services. Alternatively, unzip it (or jar xf ...) to $JBOSS_HOME/server//deploy/jbossxts.sar to provide an exploded sar tree.
In the former case you can link the bridge code against the api jar in your xts-install tree. In the latter case you can link against the api jar in the exploded sar directory under JBOSS_HOME. The release process for XTS in the latest AS will assume that the sar is deployed exploded so you probably ought to make the bridge code link against the api jar in the exploded sar under JBOSS_HOME.
BTW there is a new version of the bridge for WS-AT 1.1 / AS 5 currently on my workstation. It will get added to trunk after the 4.6.1 release next week.
Thanks for the info Andrew and Jonathan.
I will now proceed to manually build the full JTA and XTS (1.1), as you indicated, from JBoss 4.6.0.CR1. Then, after exploding this manual build's resulting jbossxts.sar into $JBOSS_HOME/server//deploy/jbossxts.sar, I will then rebuild all of the WS-BusinessActivity Framework (i.e. both org.jboss.ba.demo and org.jboss. txbridge packages).
The resulting WS-BA Framework should then be fully 1.1 compliant (I will confirm) and should work out of the box with the next EAP 5 point release (which will include XTS 1.1)