This page last changed on Jun 21, 2007 by scytacki.

This is an important obstacle to design for. I think a hub architecture would work best. - TA

We have been having problems with proxies and networks for the last year. Every school has a different setup and causes different problems.

We've had to use the HTTPClient package as a replacement for Java default networking package. This was to get through proxies that require authentication or require cookies.

The current problem we are having is with flakey network connections inside the school or between the school and us:

  • This is seen by getting incomplete files.
  • Sometimes these get cached on the proxy server and then they take a while (~ 6 hours) to update.
  • Slow networks. Even when there there is proxy server that is caching files. It still takes ~20 seconds to check the date of a file.

The files in some workspaces are checked to see if files they are valid. But this isn't the case for the workspaces with the siteconfig and student_activity_status. When a invalid file is found it...

In the short term we have taken the schools mostly offline. These means they don't get any updated files from us but we still get their log files. Problems:

  • New Students can't be added or passwords changed
  • Activities can't be disabled for particular students.
  • Activities can't be updated

We just met about this and are going to come at this from two angles.

  • We are going to setup a system so changes to our files get through no mater what. The name of each file will have the timestamp appended to it. These files are referenced by a summary file that already has this time stamp in it. So the workspace code will use this to figure what URL to request. This requires:
    o Changing the workspace code to request the correct URL, this should be set on a workspace by workspace basis, so simple web servers can still be used.
    o Make a pseudo directory that is really a php script, this script will resolve the timestamped urls to their real file names. This script needs to send back the correct proxy-caching headers. Originally we were going to do this with symlinks, but the pseudo directory will be much less error prone.
    o Changing the server so the summary file is never cached by the proxy at the school, (I believe this is done, but we need to test it SC)
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