UvA Web University of Amsterdam - UvA
Faculty of Science








Ongoing development



WS-VLAM FAQ - For users and developers

This page provides WS-VLAM users and developers with the most frequently asked questions. Please have a quick look at the following questions before you send a request to support, this can save a lot of time.

  1. You cannot create a Grid Proxy (Wrong password)
  2. Cannot get the graphical output from one of the workflow components
  3. Where can I get examples of source code for module developers?
  4. I cannot run the experiments (possible reasons)

You cannot create a Grid Proxy (Wrong password)

If you have followed the procedure of creating a Grid credential as described in the document WS-VLAM Users Guide, you should be able to create a Grid Proxy.

If you are logged on a machine where Globus is installed (ask your system administrator about the Globus installation), you can do a very simple test, but before, make sure you add the Globus bin directory to your PATH variable environment.

  • Try the following command: $ grid-proxy-init
  • You will be requested to enter your password
    • if an error message is displayed on your screen, just copy it and send it to gvlam-dev@lists.vl-e.nl
    • In case you get a message similar to the following

    • > Creating proxy ........................................... Done
      > Your proxy is valid until: Wed Mar 17 21:51:49 2004
  • Solution: The Grid Proxy creation problem is probably due to the fact that you are using a java jdk other than the Sun jdk, it is known that for example the IBM jdk security package is not compatible with the COG toolkit developed in the Globus project.
  • Action: Change your JAVA_HOME and make your that your PATH environment is also pointing to the sun java jdk bin directory (if you don't know how to do that ask your system administrator).

Cannot get the Graphical output from one of the workflow components

If you cannot get the Graphical output from one of the workflow components after you have successfully submitted the workflow to the WS-VLAM web service. You may have got the message similar to the following:

  • Cause: The passwd file in .vnc directory does not exist.
  • Action: Create a new passwd file using "vncpasswd" (the password will not be used to authenticate it is just a work around until the bug is fixed Known Bug to be fixed in the next releases.

Where can I get examples of source code (for module developers)?

You can download a tar file containing examples of code of WS-VLAM modules from: www.science.uva.nl/~gvlam/wsvlam/

I cannot run the experiments (possible reasons)

This means that one or more modules composing your experiment could not be started. There are some reasons for this problem:

  1. You don't have a .vlamrc file in your home directory (this is hidden file created when you run the first time the VL script)

    Action: if no .vlamrc in your home directory, you can create one just by running the VLscript with the option env.

    Type the following command: $ VL env

  2. You are trying to run your modules on Hosts where Globus is not installed.

    Action: If you are testing new modules, you have deployed locally, you cannot test them unless, the localhost is a Grid node (ask your system administrator if your localhost is a Grid node)

  3. You cannot start jobs on the Grid, because you are not mapped on the grid-mapfile of the hosts you want to start your module on. The are two simple explanations for this situation, either you are trying to use a host you are not allowed to use, or the WS-VLAM administrator has forgotten to add you to the grid-mapefile.

    Action: for linux users: If you know a little bit about Linux, try to submit a very simple job on the host you have selected do the following test (don't forget to set the GLOBUS env)

    • $ globus-job-run hostname /bin/ls
    • If you have an error message similar to the following:
      > GRAM Job submission failed
    • Then, you have just found the reason why you failed to run your experiment contact your WS-VLAM administrator. However, if you can execute this job, it means you have been added to the grid-mapfile.

    Action: If you cannot perform the test, contact your WS-VLAM local administrator and about the resource access policy.

  4. The modules are not deployed as specified in the document WS-VLAM developers Guide on the host you have selected.

    Action: In the current version of WS-VLAM (WS-VLAM 1.0), we do not support automatic deployment of modules. Modules need to be deployed manually on the host where you want to run them (Ask your local WS-VLAM administrator to help you deploy your module on the host you want to use. This procedure will be automated in the next versions of the WS-VLAM software.

  5. If none of the previous cases match your case, please copy the error message and log files in the vlam/var and send them to gvlam-dev_no-spam_@lists.vl-e.nl

University of Amsterdam UvA
Kruislaan 403 NL-1098 SJ
Amsterdam, The Netherlands
Tel: +31(0)20 525 7514
Fax: +31 (0)20 525 7490

Last update:
March 2013