Fission Workflow Sample: Carpool

Fission workflow sample mimics a carpool application. It tries to match a car owner who offers seats in his car and riders who are looking for one or more seats in a shared carpool. In current version for sake of simplicity there is no concept of of source & destination i.e. a single route is assumed.

Everything is a Fission function in this application and connecting the functions is done using the Fission workflow project

Architecture

There are four custom functions and two Fission workflow's built in functions used to achieve an end to end carpool application.

Please check the workflow definition in Carpool workflow spec while going over the description of each function below.

1. CarPool producer

Carpool producer produces a random car owner's with car plate and number of seats they can offer on ride.

2. Foreach

Foreach is a built in function in Fission workflow. Instead of writing a custom function for simple things like iterating over a list or checking a condition, you can use built in functions. In this case, we are getting a list of CarPool objects from CarPool producer and feeding one item at a time to CarPool validator.

3. CarPool validator

CarPool validator right now simply drops off the carpools which exceed a certain number of seats.

4. Compose

Although not clearly visible - a foreach is wrapped by a compose. Compose collects output of foreach and makes a list from individual outputs.

5. CarPool allocator

Carpool allocator generates a set of rider requests and matches them with carpool requests. Currently the matching algorithm is rather rudimentry. This function also exposes a REST endpoint which reports matched rides, unmatched cars and unmatched riders.

6. Carpool dashboard

CarPool dashboard consumes the output of CarPool allocator and displays a simple dashboard

Dashboards

Try it out

If you have Fission and Fission Workflows installed, you can use specs to apply all functions and visit the dashboard URL at $FISSION_ROUTER/carpoolweb/index.html

$ fission spec apply
uploading archive archive://carpool-validator-1-0-0-jar-with-dependencies-jar
uploading archive archive://carpool-allocator-1-0-0-jar-with-dependencies-jar
uploading archive archive://carpool-producer-1-0-0-jar-with-dependencies-jar
5 functions created: carpool, cpallocator, cpproducer, cpvalidator, carpool-web
1 HTTPTrigger created: 408fd31e-5149-4c0c-acb0-9445d4a05f37
2 environments created: java, python
5 packages created: carpool-workflow-wf-yaml-hiri, carpool-allocator-1-0-0-jar-with-dependencies-jar-owhb, carpool-producer-1-0-0-jar-with-dependencies-jar-owhb, carpool-validator-1-0-0-jar-with-dependencies-jar-owhb, cp-web-pkg

Future work

Although a working examplem, this can be enhanced further to make a real world carpool application

• Split the car riders generation into a different function.
• Make the matching algorithm more robust
• Use a document store to store requests from carpool creators and riders and then clean up based on a reasonable timeout like 30 minutes if no match found.