Synchronizing multimaster meshes with deltas

DET provides the means of performing ‘incremental" exports and imports, which helps you keep the content in your multimaster mesh synchronized and up to date.

For example, you can run regular exports from your “source" mesh that represents all the content you want other meshes to contain. Using the new options allows you to export only content that has been modified or deleted so that your target mesh are consistent with the source mesh.

Delta exports

These command-line options allow you to perform an delta export:

• --baseline (short form: -b)
  Specifies a baseline export against which to compare the current export. This requires that either --incremental or --delete be specified during export.
• --incremental (short form: -incr)
  Of the content specified by the filter file, export only that which has been added or modified since the baseline. If this option is not given, all content specified by the filter file is exported. Must be used with --baseline.
• --delete (short form: -del)
  Include in the export any content in the baseline that is not specified by the filter file, marked “as deleted". If this option is not given, nothing is exported “as deleted". Must be used with --baseline.

Here is what happens when you use --delete and --incremental in combination with --baseline during an export:

• No incremental export options.
  All content specified by filter file is exported.
• -incr
  All content specified by filter file that is new or changed since the baseline is exported.
• -del
  All content specified by filter file is exported (since -incr is not given), plus all content in the baseline that is not specified by the filter file (“as deleted").
• -incr -del
  All content specified by filter file that is new or changed since the baseline is exported, plus all content in the baseline that's not specified by the filter file (“as deleted").

Delta imports

This command-line options allows you to perform a delta import (if certain options were given during export):

--delete (short form: -del)

If the --baseline option was given with --delete during export, then using the
--delete option during import will delete objects that have been marked for deletion from the export.

If the --baseline option was given with --delete during export, but you do not use --delete during import, the items marked for deletion will not be deleted but rather renamed. For more information on cases in which some content may never get deleted and always renamed (for example, if the object has a dependency elsewhere in the mesh) then see Importing deleted content.

Mesh synchronization usage scenario

Here is what a typical incremental export and import cycle might look like when content in the source mesh has been both deleted and modified:

• Initial, full export of a filter that exports Application Configuration content:
  cbt -e content/appConfig.0 -f ac_Filter.rdf -cf meshA_Config
• Import exported content into another mesh:
  cbt -i content/appConfig.0 -p overwrite -cf meshB_Config
  Content is changed and deleted in source mesh.
• Export the modified and deleted content from the source mesh using -b and -incr and -del:
  cbt -e content/appConfig.1 -f ac_Filter.rdf -b content/appConfig.0 -incr -del -cf meshA_Config
• Import the delta into the destination mesh, updating the modified content and deleting the deleted content:
  cbt -i content/appConfig.1 -p overwrite -cf meshB_Config -del
• Repeat steps four and five every time you want to update content, using the most recent export as your baseline. For example, on the next round you would use:
  • Export content/appConfig.2 with -b content/appConfig.1.
  • Import content/appConfig.2.