ERM Agreements Title addition and removal feed

N.B. Applies to the Agreements Internal KB only

Current situation or problem:
Institutions wishing to drive discovery systems off data stored in Agreements need to know which titles are currently part of the institutions electronic collection - i.e. titles that can be accessed by the institution as a result of agreements which include those titles.

Because the definitions of what constitutes a "current" title rely heavily on dates that are stored in Agreements and the Agreements internal KB, the list of current titles can change from day to day without any changes to the underlying stored data. For example if an Agreement Line has an "active to" date, once that date is passed that agreement line is no longer "active" and all of the titles that form part of that agreement line cease to be part of the current title list.

The implication of this is that to keep a discovery system up to date, a complete export of all current titles would be required daily - which would be very inefficient.

This feature is to support support the ability to produce a log of additions and removals of resources to/from the library collection based on agreements, agreement lines, and package information (from the internal KB). It should be possible to query a list of changes since a specific date. If queried from "day 0" (i.e. all changes ever), the response can be used to reproduce the current state of available resources by 'replaying' the list of changes over the entire time period.

In scope
Creating a mechanism which can be used to access a list of additions and removals of resources from a libraries collection which can be used to keep an up to date accurate list of the current accessible electronic collection (as managed in Agreements using the Agreements internal KB)

Out of scope
Any resources not described in Agreements internal KB

Use case(s)
Keeping a union catalogue or discovery system up to date with a list of current titles/holdings available through ERM agreements.