Workflow

hermes-server

• 1. loads its local cache
• 2. checks if its dataschema has changed since last run, and emits the resulting removed events (if any), and the new dataschema
• 3. fetches all data required by its datamodel from datasource(s)
  • 3.1. enforces merge constraints
  • 3.2. merges data
  • 3.3. replaces inconsistencies and merge conflict by cached values
  • 3.4. enforce integrity constraints
• 4. generate a diff between its cache and the fetched remote data
• 5. loop over each diff type: added, modified, removed
  • 5.1. for each diff type, loop over each data type in their declaration order in the datamodel, except for removed diff type, for which it is the reverse declaration order
    • 5.1.1. loop over each diff item of current data type
      • 5.1.1.1. generate the corresponding event
      • 5.1.1.2. emit the event on message bus
      • 5.1.1.3. if event was successfully emitted:
        • 5.1.1.3.1. run datamodel commit_one action if any
        • 5.1.1.3.2. update the cache to reflect the new value of the item affected by event
• 6. once all events have been emitted
  • 6.1. run datamodel commit_all action if any
  • 6.2. save cache on disk
• 7. wait for updateInterval and restart from step 3. if app has not been requested to stop

If any exception is raised in step 2., this step is restarted until it succeeds.

If any exception is raised in steps 3. to 7., the cache is saved on disk, and the server restart from step 3..