FAQ

JWIG is so cool! How can I contribute to the project?

JWIG is Open Source and all contributions are welcome. However, you should probably coordinate your efforts with the current JWIG team to allow everyone to benefit from your work.

I have carefully followed the JWIG installation instructions, but nothing happens when I try to run the Hello.jwig example from a browser. What can be wrong?

Try looking in the Apache Web server error log file and in the service log file. If nothing shows up, try setting LogLevel in httpd.conf to debug and restart the Apache server.

Why do I have trouble receiving form input in my JWIG service?

Hints from the HTML specification: The "get" method restricts form data set values to ASCII characters. Only the "post" method (with enctype="multipart/form-data") is specified to cover the entire [ISO10646] character set. The content type "multipart/form-data" should be used for submitting forms that contain files, non-ASCII data, and binary data.

I get a parse error from the JWIG compiler, but the error message looks strange. What's happening?

JWIG uses a simple JFlex-based translation from JWIG code to Java code and then compiles the Java code with a standard Java compiler. This means that parse and type errors in the JWIG program are often not detected until the Java compiler runs. For a future version of JWIG, we plan to use a more intelligent translation from JWIG to Java to solve this problem.

Why do I get a ConcurrentModificationException when running the JWIG analyzer?

This appears to be caused by a bug in J2SDK 1.4, which confuses the Soot classfile parser used by the analyzer. (Try running javap on your class files - that tool is also confused...)

Why do I get a runtime error "java.lang.InternalError: internal error: SHA-1 not available"?

This appears to be a bug in J2SDK 1.4. Try inserting the following line in jwig.policy:
  permission java.security.SecurityPermission "putProviderProperty.*";

Why do I get an InvalidClassException at runtime?

You have probably overwritten the service class files with incompatible classes such that the stored state cannot be unserialized. See the section Updating a Running Service in the user manual.

Why do I get an ClassNotFoundException at runtime?

Make sure the Apache user has read permission to the application directory and all its ancestor directories. (Execute permission is not enough.)

I have a JWIG problem not mentioned above. What do I do?

Send us an email and we will try to help.