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Synchronization is needed when you have multiple sites using OpenMRS with separate databases and you want them to copy data to each other. In this situation, one site has to act as the "Parent", and one acts as the "Child". The Parent is always the computer or site that is most central. Multiple child sites send their data up to the parent site for dissemination. Children/parent sites can be set up in a multi hierarchy way. (eg. a parent server can have a parent server). The parent/child servers can be connected by a network continuously, connected occasionally, or not connected at all.

The Sync Module works by keeping track of all changes going through the API into the database. These changes are then replayed on the other server(s). The changes are stripped of all primary key references. Instead, UUIDs are used to compare and reference other data. Because of this, the parent/child servers must be exact duplicates when sync is first started.

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Formentry Module

If using the Formentry Module 5.x and below with the Sync Module you must take care with how the concepts are developed. Formentry still depends on internal concept.concept_id values being the same on all servers. The sync module cannot guarantee that to be the case. So all concept/form development must happen on one and only one server in your sync network.

See full note on Formentry Module wiki page.

History of the Sync Project

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