Strategy interface design epic

[TimDaub]

There are currently a couple of structural or architectural issues we're facing with our strategies as it currently stands. To highlight that we may be better off making progress by focusing on fixing those, I'm collecting them in this issue.

• we want to implement Extract Transform Load, but load doesn't exist yet.
• we tend to use extractor strategies for filtering or for access files (because we cannot do it in onLine of a transformer strategy: add strategies to transform logs to subgraph #234 (comment)
• merging results of two different strategies is painful and all past workarounds have lead to bad code structure #236
• that strategy implementers have to pass result: null in the messages of a function init may be confusing schema#42
• we should allow calling a transformer with a specific file name #241
• writing all extractor messages to flatfiles may mean sequentializing the entire crawl path #244
• The inputs of strategies when they're e.g. file paths can not always be structurally guaranteed in a crawl (e.g. that soundxyz-get-tokenuri can access soundxyz-call-tokenuri-transformation - because in an interface no sound nfts may have been minted) #243
• extractor strategies must define other strategies as dependencies in interface #220
• We're hard coding the smart contracts and events that we're supposed to filter in call-block-logs but we should pass them as arguments #219
• tight coupling between strategies leads to lots of refactoring effort #218
• function transform isn't redirecting new messages to the worker #214
• call-block-logs extractor makes process run out of heap memory #193
• When writing strategy outputs, `JSON.stringify' doesn't canonically serialize JSON objects (e.g. it assumes the order of keys in the literal). For testing snapshot writes, this can become a problem. Replace JSON.stringify with a canonical serializer #91
• interface definitions in readme are "fake typescript" and should be replaced with e.g. real typescript interfaces #69
• error handling is done badly in transformer strategies currently #63
• Currently strategy names don't follow a format/convention to it's hard to give good and consistent names #61
• It's unclear (via convention) that when passing a string in a strategy's return to write it'd get written to disc #50
• Consider single file format for strategy definitions #292
• the exported props object in a strategy implemenation is useless #297
• the exported version field in some strategy interfaces makes no sense #298

[neatonk]

Here's another one #292