The http implementation of BTT Message is provided as bttmessage.jar and an eclipse plug-in com.ibm.btt.message_7.1.0.
You can use the bttmessage.jar in server side and use the plug-in in client side.
You can find them at: <BTTInstallationPath>\plugins\com.ibm.btt.remote_7.1.0\lib\
Please make sure they are in the runtime CLASSPATH of your project.
See the following steps to configure BTT Message with HTTP implementation