Elevator

The Elevator provides simple polling based updates from CouchDB to PouchDB within Tangerine®.

Overview

The following API endpoints were meant to be called in order version, revs, fetch. The version is retrieved to see if there is a desire for the client devices to update. If the local version doesn't match the server version, the update sequence is triggered. Local document ids can be sent in to the revs endpoint to see which need to be updated. The server revs are compared with the local revs and all differing document _ids are marked to be fetched. The server also sends new documents that are not archived as well as an update document that will contain any javascript necessary for hotfixing small bugs.

This service provides a convenient alternative when true CouchDB replication is not required and only a server to client overwrite is required.

Usage

Get the version of a specified group

curl localhost:4448/version/test_group
# {"_id":"version","_rev":"...","number":"1"}

Get revision numbers for specific documents

curl localhost:4448/revs/test_group -H "Content-Type: application/json" -X POST -d '{"ids":["one"]}'
# {"total_rows":1,"rows":[{"id":"one","key":"one","value":{"rev":"..."}}]}

Get a set of documents

curl localhost:4448/fetch/test_group -H "Content-Type: application/json" -X POST -d '{"ids":["one"]}'
# {"total_rows":1,"rows":[{"id":"one","key":"one","doc":{...}}]}

Structure

The routes are broken down into several functions for separation of concerns and to make testing easier. For express's purposes .route is the only one necessary. Like this:

app.get('/', require('./routes/version').route)

The others are used by the route function, partially for separation of concerns and partially for testing.

clean takes a req from express and returns valiables.
validate validates the cleaned variables and returns nothing if everything is ok.
work returns a promise and resolves when the actual work is done.
route uses clean, validate, work in that order and then catches any errors

The benefit is that the unit tests are really easy to write and the real logic of the program is all in work. This structure is based very loosly on go-kit.

Security

Certain documents important to the secure functioning of your application are blacklisted and not allowed to be downloaded by this service. The blacklist is located in Conf.js.

const SENSITIVE_DOCS = [
  'settings',
  'configuration',
  ''];

Client code

The ./client directory contains a javascript class that can be used for integration into any PouchDB-CouchDB web application.

See the ElevatorClient readme for more info.

License

GPLv3

fetmar / elevator

readme