[BEAM-1195] Give triggers a cross-language serialization schema

• Type: New Feature
• Status: Resolved
• Priority: P2
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: beam-model
• Assignee: Kenneth Knowles
• Reporter: Kenneth Knowles
• Created: 21/Dec/16 19:27
• Updated: 16/May/20 13:56
• Resolved: 23/Mar/17 04:48

Description

We have recently gotten to the point where triggers are just syntax, but it is still shipped via Java serialization. To make it language-independent, we need a concrete syntax.

Something like the following is fairly concise, tag adjacent to payload. I haven't bothered making up fully verbose/namespaced URNs here.

{
    "$urn": "OrFinally",
    "main": {
      "$urn": "EndOfWindow",
      "early": <foo>
    },
    "finally": {
      "$urn": "AfterCount",
      "count": 45
    }
}

Issue Links

• relates to: BEAM-1328 Serialize/deserialize WindowingStrategy in a language-agnostic manner
• links to: GitHub Pull Request #1988