Monthly Archives: September 2009

Investigating site exports from Sakai 2

So the export/import file format investigation has reached some early conclusions regarding the use of Moodle’s backup schema and it looks like we will be looking elsewhere. See: Moodle export-import format investigation and the email thread itself.

While we ponder IMS Commmon Cartridge, I thought I would investigate what it would take to provide the capability of exporting Sakai 2 sites into the existing Sakai 2 proprietary XML format. This is a long standing request within the Sakai community, but one that no one has been willing to tackle. This is a bit of a dodgy situation as most tools do participate in the method EntityTransferrer.transferCopyEntities(), so it is possible to copy the structure of a site from semester to semester. I use the term “structure” because this is common practice among LMS applications to only copy what might be termed a “template” across semesters. For example, this copy process would include content like forum definitions, but not student responses; grade book items, but not student grades, etc.  The primary use case is an instructor who taught a class last semester can import that previous site into the current semester’s course site to reduce setup time.

So far so good – but here is where things get a bit dodgy… The EntityTransferrer.transferCopyEntities() method copies entities directly from one site to another (i.e. without writing any of these entities to XML). While Sakai 2 does have a mechanism for writing entities to XML, called ArchiveService.archive(),there are at least two problems with it: 1) Unlike transferCopyEntities(), all student positngs, grades, etc. are included in the XML produced (i.e. more like  a site backup), and 2) only a small subset of tools actually implement the ArchiveService.archive() interface! So this leaves me wondering:

  1. Does anyone actually depend on ArchiveService.archive()? My instincts tell me no since most of the tools do not implement it. Am I wrong?
  2. Could we usurp the ArchiveService.archive() interface and change the behavior so that only site structure is exported without student content?
  3. Do we leave ArchiveService.archive() alone and create a new API?
  4. How many tools still need to implement archive()?


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Sakai 3 export/import formats research

Since Sakai 3 is a ground-up rewrite, there is plenty of opportunities to rethink assumptions that have accumulated over the years.  One of those areas where a fresh look should do some good is in course export/import formats.  Sakai 2 has its own proprietary format which provides a “full fidelity” capability to move from one course site to another without losing anything.  While not losing anything is desirable, it comes at quite a cost; i.e. not being compatible with anything else on the planet.  This approach is not uncommon and I see now that Moodle also has its own proprietary format.

While there are some good open standards for course export/import (e.g. IMS Common Cartridge or SCORM), they will not provide a “full fidelity” export/import workflow where one could export from Sakai 2 and then import into Sakai 3; i.e. some information would get lost in the translation.  Now, supporting these open standards would have other important benefits, they are not first order solutions for simply getting from Sakai 2->3.  My hopes are that one day an open standard could be expressive enough to cover such a use case, but the innovation curve in the applications and tools may always exceed the ability of a lowest common denominator solution.

With that said, we thought it would be beneficial to see if Moodle’s export/import format provided enough capability to move data from Sakai 2->3 without losing any critical structure.  If this worked out, we would have one great feature out-of-the-box: the ability to move from a course from Moodle to Sakai and vice-versa.  It will be interesting to see how this works out and I will keep you updated as progress is made…

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