i am wondering what is use of jbossall-client.jar ?
It's a bundling of all JBoss client code into a single JAR, for those who don't want to bother with selecting the individual smaller JARs.
Up to JBoss version 4.2.3 these file contains client code for application.
But since JBoss 5.0 these file contains only dependences against other libraries from server client directory. If you want use it you must put also other jar file on in the same directory as jbossall-client.jar. These is excerpt from readme.txt file from jbossall file:
This jar file contains a classpath reference to various client jar files used by jboss client applications.
Each of the jar files in the following list must available in the same directory as the jbossall-client.jar, Otherwise they will not be found by the classloader.
In readme.txt you can also find the list jar files against which jbossall-client has dependencies.