I doublechecked inside alfresco.war (which got created by install) that it indeed has all the new and correct XML and class files and the new jar file. I manually copied the my.jar inWEB-IN\lib and restarted Tomcat.
I am fine if I have to manually copy my.jar yo WEB-IN\lib (although I should not).
Perhaps I am missing something else. I am not sure why I keep getting 404 error when I try to display the sercice/index.html page.
Re: Edited URL in an existing Java-backed websctript is now showing up
Check that your generated artifact is correctly deployed.
Go to <tomcat_dir>/webapps/alfresco/WEB-INF/lib and find your artifact. First of all, check that there's only one customized jar in this folder. When you change artifact versions, old jars remain there. Clean up old jars if that's the case.
Next, open your jar with any zip tool, and check that it effectively contains your modified file. If that's not the case, stop tomcat and execute apply_amps with the -force option.
Start tomcat, and check again that your deployed jar contains the changes you expect.