Project Operation

Project Creation

The ApiLogicServer CLI create (or create-and-run) command creates the project structure shown below - for more information, see here.

 

API Execution: api_logic_server_run.py

Execution begins in api_logic_server_run.py. Your customizations are done to the files noted in the callouts below.

api_logic_server_run.py (a file created in your ApiLogicProject) sets up a Flask app, the database, logic and api:

1. Database Setup: It importsapi/expose_api_models which imports database/models.py, which then imports database/customize_models.py for your model extensions. api_logic_server_run.py then sets up flask, and opens the database with db = safrs.DB

2. Logic Setup: It then calls LogicBank.activate, passing declare_logic which loads your declared rules into Logic Bank.

3. API Setup: It next invokes api/expose_api_models. This calls safrs to create the end points and the swagger information, based on the created database/models.py (the models used by the SQLAlchemy ORM). It finally calls api/customize.py where you can add your own services. The sample includes a trivial Hello World, as well as add_order.

Logic Execution

SAFRS API listens for API calls, e.g., from the Admin App. When updates are issued:

L1. Invokes SQLAlchemy updates: SAFRS calls SQLAlchemy, passing a set of rows comprising a database transaction

L2. before_flush: SQLAlchemy provides a before_flush event, where all the update rows are assembled and passed to Logic Bank (no relation to retail!).

L3. Logic Execution: Logic Bank reviews the rows, and based on what has change, prunes rules for unchanged data, and executes / optimizes relevant logic in an appropriate order.

 

Row/Commit Logic

The console log below illustrates that the rows are processed in 2 distinct "logic loops":

• Row Logic - rules are executed, with chaining, as received in the before_flush event
• Commit Logic - commit constraints and events are executed after all row logic is complete*

Two logic loops are provided so that parent logic can see all the adjustments of the child logic.

• When the Order is first seen at the top of the log, the OrderDetails have not yet been processed, so their adjustment logic has not been run. So, sums/counts will be 0 (e.g. OrderDetailCount).

• The Commit Logic loop is therefore provided after all the adjustment processing has occurred.

  • So, if you want to verify that Orders have 1 or more OrderDetails by placing a constraint on OrderDetailCount, this would need to be a CommitConstraint.

Row Logic processing:

 

Admin App Execution: ui/admin/admin.yaml

http://localhost:5656/ redirects to ui/admin/index.html which loads the react-admin single-page app into your browser.

It then loads your ui/admin/admin.yaml, and responds to the various clicks by invoking the API (and hence the update logic), or the swagger at http://localhost:5656/api.