Routing and branching

Routing is how a workflow makes decisions. A node publishes each message on a named output port, and edges listen to ports. This page shows the common patterns. The full option list for each node is in the plugin reference.

An edge with no sourcePort receives everything except messages on the error port. An edge with a sourcePort receives only that port. A message on a port with no listening edge is dropped, so wire every port you care about.

Route on an exit code

The process plugin can send a message to success or failure depending on the command’s exit code. Set failureMode to CONTINUE so a non-zero exit is routed instead of failing the node.

{
  "nodeId": "tests",
  "type": "PROCESS_EXECUTOR",
  "config": {
    "command": ["run-tests"],
    "timeout": 120,
    "failureMode": "CONTINUE",
    "routeByExitCode": true
  }
}

{ "source": "tests", "target": "report-pass", "sourcePort": "success" },
{ "source": "tests", "target": "report-fail", "sourcePort": "failure" }

Route on an HTTP status

The HTTP plugin does the same for the response status with routeByStatus:

{
  "nodeId": "probe",
  "type": "HTTP_REQUEST",
  "config": {
    "url": "https://service.example.com/health",
    "method": "GET",
    "timeout": 5,
    "failureMode": "CONTINUE",
    "routeByStatus": true
  }
}

A successful response goes to success; an error status goes to failure.

Branch on an expression

The BRANCH plugin evaluates cases against the message and sends it to the port named by the first matching case.

{
  "nodeId": "decide",
  "type": "BRANCH",
  "config": {
    "mode": "EXPRESSION",
    "cases": {
      "payload.coverage >= 80 && payload.lintErrors == 0": "pass",
      "payload.coverage < 80 || payload.lintErrors > 0": "fail"
    },
    "allowMultipleMatches": false,
    "strictMode": true
  }
}

{ "source": "decide", "target": "report-pass", "sourcePort": "pass" },
{ "source": "decide", "target": "report-fail", "sourcePort": "fail" }

The port names come from the case values. There is also an exact-match mode for comparing one value against fixed cases.

Filter

FILTER passes only the messages that match a condition and drops the rest:

{ "nodeId": "keep-active", "type": "FILTER", "config": { "condition": "payload.active == true" } }

Validate and reject

VALIDATE checks required fields and types. Messages that pass continue; messages that fail go to the invalid port, where you can send them to a report or a dead-letter node.

Fan out to several recipients

RECIPIENT_LIST sends one message to several recipients, optionally in parallel. Each recipient is a port:

{
  "nodeId": "fan-out",
  "type": "RECIPIENT_LIST",
  "config": { "mode": "STATIC", "recipients": ["slack", "email", "pager"], "parallel": true }
}

{ "source": "fan-out", "target": "slack", "sourcePort": "slack" },
{ "source": "fan-out", "target": "email", "sourcePort": "email" },
{ "source": "fan-out", "target": "pager", "sourcePort": "pager" }

To send the same message to several nodes without choosing, give the node several outgoing edges without ports; every child receives every message.

Route failures

With onError: ROUTE in a node’s engine object, a message that fails all its attempts leaves on the error port with its failure details. See Failure handling.

{ "source": "classify", "target": "dead-letter", "sourcePort": "error" }

Rejoin branches

Several branches can lead into one node, often a shared terminal. When that node has several parents, its join rule decides what a failed branch means; see Nodes, edges and ports.

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Routing and branching

Route on an exit code

Route on an HTTP status

Branch on an expression

Filter

Validate and reject

Fan out to several recipients

Route failures

Rejoin branches

​Route on an exit code

​Route on an HTTP status

​Branch on an expression

​Filter

​Validate and reject

​Fan out to several recipients

​Route failures

​Rejoin branches

​Related

Route on an exit code

Route on an HTTP status

Branch on an expression

Filter

Validate and reject

Fan out to several recipients

Route failures

Rejoin branches

Related