You can invoke the migration tool using either gui or cmd line. Follow the link "Invoking the Migration Tool" http://wiki.glassfish.java.net/Wiki.jsp?page=M2G-onlineHelp for more info and examples. I personally prefer the cmd line usage.
The java.util.MissingResourceException exception you encountered is a bug. Please file an issue on https://migrate2glassfish.dev.java.net/servlets/ProjectIssues IssueTracker for this. The bug can mask the real problem which is that InputArchive was specified in GUI but no archive file ( war/ear/jar file ) was specified (this is as far as I can tell just by looking at the code).
The DD should be bundled in an ear/war/jar file. I used war only as an example in my previous post. As Vince pointed out, exporting a WebSphere application does produce an archive with all the necessary WebSphere specific DDS. The GF Migration tool assumes that the archive used as input is J2EE / Java EE compatible (it does perform some checks).
[Message sent by forum member 'sekhar' (sekhar)]