And the circle of life continues! I have seen exactly this method in 2004-2006 but with XML.

If you are reading this, and you think it is a good idea, please don't follow it as it is not.

Back in 2006-2009 I worked at MobiTV, which we had the same exact way/method of programing our mobile apps, on J2ME/feature phones. The made up language was called CEF which was based on XML. While the idea is sound in paper, This turns really fast into an ugly, debug everywhere type of scenario, where it is hard to both develop and debug properly.

The only way this is ok, is when you have some fully automated UI tool, that stores some kind of state, and retrieves it back, but with no human intervention and some very very limited logic. Otherwise you are in a world of pain. If you try to include real application logic into something like this it is going to hurt your business long term.

It will turn your business logic like some Maven configuration, full of gotchas and more.

sebmellen

Maybe you can tell me if there's a better solution. I'm open to hearing any options because I'm at a loss of how to do this otherwise:

Say we have a schema which defines certain data. Let's say it's a "credential" which is a "COVID-19 Back to Work Credential." The credential is valid in the case that someone either 1) has a COVID vaccination or 2) has a negative COVID test in the past 72 hours. That data might look like this:

  {
    "credentialName": "COVID-19 Back to Work Credential",
    "credentialIssuer": "Acme Labs Inc.",
    "credentialData": {
      "rapidSarsCov2PCRTest": {
        "hasTestResult": true,
        "testResult": "negative",
        "testTime": 1622145851
      },
      "covid19Vaccination": {
        "hasVaccination": false
      }
    }
  }

Now, say I want to define the conditions under which this "credential" is valid or invalid, but I want to include this "matrix" within the schema (not any business logic, just matrix logic that pertains to the data within the schema itself).

Optimally, I'd be able to do this within the same schema or file.

With JsonLogic, that might look like this (probably flawed logic, just a demo, not using this in production, may cause your computer to go up in flames, etc.):

  {
    ...

    "parsingMatrix": {
      "if": [
        {
          "or": [
            {
              "===": [
                { "var": "credentialData.rapidSarsCov2PCRTest.testResult" },
                "negative"
              ]
            },
            {
              "===": [
                { "var": "credentialData.covid19Vaccination.hasVaccination" },
                true
              ]
            }
          ]
        },
        "valid",
        "invalid"
      ]
    }
  }

Can you think of another way to do this that doesn't rely on using JsonLogic or something like it (or a cleaner method for doing it in JSON)?

goto11

How about representing the logic as a JavaScript expression:

    (credentialData.rapidSarsCov2PCRTest.testResult==='negative')
      || credentialData.covid19Vaccination.hasVaccination) 
          ? 'valid' : 'invalid'

Seem easier to read and maintain to me.

sebmellen

I'd love to do this, the only problem there is we're sharing this data between systems which use different runtimes. A client who runs a Python environment might not easily be able to make use of that logic. With JsonLogic, that would theoretically be possible.

goto11

Btw google have something almost exactly like this: https://github.com/google/cel-spec