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Revision 1 (Shuvam Misra, 21/09/2023 01:10 PM) → Revision 2/21 (Shuvam Misra, 21/09/2023 03:40 PM)
# Algorithms and data structures for the flow engine
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We will refer heavily to the algorithms and data structures of the BRE here.
Here too, we need a rules schema, rulesets and a matching engine.
## Rules schema
In the BRE, each rules schema has two parts: the pattern schema and the action schema. Each `rulesschema` rules schema block is tagged with a `class` attribute, specifying which class the schema applies to. There is one rules schema for each class of entities.
In the flow engine, there is no `class` -- there is a `process` instead. A workflow schema applies to a process.
The pattern schema specification is identical here to that used in the BRE.
In the flow engine, there is no `actionschema`, but a `flowschema`. The flow schema is much simpler than an action schema. simpler. The output of a flow engine matching exercise is just the ID of one step. step ID. Therefore the flow schema here is a list of possible steps.
``` json
"ruleschema": {
"process": "customerkyc",
"patternschema": {
"attr": [{
"name": "cat",
"type": "enum",
"vals": [ "textbook", "notebook", "stationery", "refbooks" ]
},{
"name": "mrp",
"type": "float"
},{
"name": "fullname",
"type": "str",
},{
"name": "ageinstock",
"type": "int"
},{
"name": "inventoryqty",
"type": "int"
}]
}
"flowschema": {
"steps": [ "initialdoc", "aadhaarcheck", "pancheck", "bankdetails", "referenchk", "complete" ]
}
}
```
In the example above:
* `class` is replaced with `process`
* `patternschema` remains unchanged
* `actionschema` is replaced with `flowschema` and the structure of `flowschema is simplified to just one array of words. Each word here is an ID of a step. So, the `flowschema.steps` lists all the valid steps which the flow engine may return after matching an entity with the rules.