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Notice that, the Graph API is parallel with SQL. The user can use both ways to create a rule. Internally, SQL queries are converted into a DAG. Thus, it is a subset of graph API.

Proposed API

We extend the rule API to add a field graph. It is mutual exclusive with sql field.

POST http://{{host}}/rules
Content-Type: application/json

{
    "id": "rulePv",
    "graph": {the json to describe a DAG}, || "sql":"",    
    "options":{}  // optional
}

An example to create a rule with graph API.

POST http://{{host}}/rules
Content-Type: application/json

{
  "id": "rulePv",
  "name": "规则ui",
  "graph": {
    "nodes": {
      "abc": {
        "type": "source",
        "nodeType": "mqtt",
        "props": {
          "datasource": "demo"
        }
      },
      "myfilter": {
        "type": "operator",
        "nodeType": "filter",
        "props": {
          "expr": "temperature > 20"
        }
      },
      "logfunc": {
        "type": "operator",
        "nodeType": "function",
        "props": {
          "expr": "log(temperature) as log_temperature"
        }
      },
      "sinfunc": {
        "type": "operator",
        "nodeType": "function",
        "props": {
          "expr": "sin(temperature) as sin_temperature"
        }
      },
      "pick": {
        "type": "operator",
        "nodeType": "pick",
        "props": {
          "fields": ["log_temperature", "humidity"]
        }
      },
      "mqttpv": {
        "type": "sink",
        "nodeType": "mqtt",
        "props": {
          "server": "tcp://syno.home:1883",
          "topic": "result",
          "sendSingle": true
        }
      },
      "mqtt2": {
        "type": "sink",
        "nodeType": "mqtt",
        "props": {
          "server": "tcp://syno.home:1883",
          "topic": "result2",
          "sendSingle": true
        }
      }
    },
    "topo": {
      "sources": ["abc"],
      "edges": {
        "abc": ["myfilter", "sinfunc"],
        "myfilter": ["logfunc"],
        "logfunc": ["pick"],
        "pick": ["mqttpv"],
        "sinfunc": ["mqtt2"]
      }
    }
  }
}

Graph model

The graph model is represented by JSON. It is composed by two part:

• nodes to define each node in the graph with properties.
• topo to define the pipeline.

Nodes

All the source/sink and operator or functions can be presented as a node including built-in and plugin. Currently, we only provide nodes which is also shared by SQL. In the future, it is possible to provide more built-in nodes that cannot be mapped to SQL operators.

In the initial version, the below built-in nodes will be provided:

• Source
  • mqtt
  • edgex
  • zeroMq etc.
• Sink
  • mqtt
  • file
  • tdengine etc.
• Operator
  • Function
    • arithmetic
    • string etc.
  • Filter
  • Pick
  • Window
  • Join
  • Group

UI Draft

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