Create an order API

Develop a 'thick' order API that encompasses the business rules for creating, updating and 'deleting' financial objects. It will sit on top of APIs that deal with line items related to contributions, memberships and participants, and will allow tax line items to be managed properly.

The term 'order' in the API is not completely accurate, since the functionality overlaps significantly with invoices.

The API signature will be similar to those for existing APIs that interact with a table in the schema, like members, participants, contributions and line items. However, there will be no civicrm_order table. Instead it will be designed to create and update financial objects according to http://wiki.civicrm.org/confluence/display/CRM/CiviAccounts+Data+Flow. In addition to this financial accounting, it will be responsible for creating, updating, and deleting the membership, participant and pledge_payment records associated with line_items in the order.

Detailed spec is being developed at http://wiki.civicrm.org/confluence/display/CRM/Order+API , based on http://forum.civicrm.org/index.php/topic,31242.msg134061.html#msg134061, and responding to points from Coleman at http://forum.civicrm.org/index.php/topic,31242.msg134337.html#msg134337

It is in scope to handle recurring payments, partial payments, premiums, and also refunds to the minimal level they are currently supported. The API will be designed to support existing front office and back office workflows and anticipated integrations to record transactions from commerce plugins and modules in the CMSes. Refactoring front and back office UI's is not in scope for this effort. Improved import functionality via the API may be a side-benefit, but is not in scope.

Review spec against bookkeeping requirements for other sorts of transactions, eg grants, expense claims, refunds.