Add re-indexing option to the Admin API

[westei]

As software updates and connecting to a different Mongo DB require a full re-index an Admin needs the possibility to trigger a re-index via the Admin API

[mrsimpson]

@westei will you be able to integrate this into 0.6.1? This release will make a re-index necessary, so having it there would be beneficial

[westei]

I can add an Webservice that allows to trigger re-indexing. For an UI integration I would need the help of @ja-fra

[westei]

@mrsimpson Noticed that adding a re-indexing option to the Admin API does not do the trick, as in a Cloud setting the Solr Indexes are only local, but the Admin UI is global. So by calling this function one would only trigger re-indexing on the local Solr index. All other cloud instances would not perform the re-indexing.

To provide this functionality we would require some kind of notification system - an infrastructure we currently do not have in place.

IMHO it is better to provide a possibility to detect an update during application startup and perform a full re-index in such cases. WDYT?

[westei]

Implemented a feature to the conversation index that allows to detect updates to the index.

After incompatible changes to the schema.xml or the indexing logic the ConversationIndexConfiguration#CONVERSATION_INDEX_VERSION needs to be increased.

A change of this version will trigger a full re-build of the conversation index on the next startup.

This replaces an older workaround that (by default) enforced a full rebuild on every startup (now the default is false)

[westei]

for validation one can look for INFO level loggings on startup:

• in case of a full re-index because of a version update the log will contain conversation index contains documents indexed with an outdated version - full re-build required
• in case of a partial update (no version update) the log will note Perform partial update of conversation index (lastSync date: {date})
• in case a fill re-index is forced on every startup (smarti.index.rebuildOnStartup=true) the log will note full re-build on startup required via configuration