Create the choreography

AMPLIFY Choreography text-based command line interface (CLI) is used to create the choreography. Choreography allows the publishing service to execute the service and publish the output without having to be aware of the subscribing services. The subscribing services listen for new publish events and receive the update.

Before you start

• The business service must be created and registered. Once the service is registered, you are automatically provided with steps that you can use in your choreography. See Create and deploy business services.
• Use the CLI step list command to list the available steps. See List available AMPLIFY Choreography services.

Objectives

Use CLI commands to create a choreography that you can then define with JSON services.

• Create the choreography
• Define the choreography
  • Single service
  • Two parents with no children service
  • One parent with one child service
  • One parent with two children service

Create the choreography

The choreography add command creates the choreography.

FilePath = the path to the JSON file where the choreography is defined.

Define the choreography

A choreography can contain one or more services. Services can be defined so that they run in parallel, or run in a parent / child relationship or in a combination of both.

When a choreography is executed, any payload passed in will be passed to all "parent" services. All parent services will run in parallel.

Child services do not receive the payload that is passed in when the choreography is executed; however, they do receive the output from their parent service as input.

Child services run after their parent service has completed.

JSON service examples

Single service

{
	"choreographyName": "Choreo_Single_Service",
	"stepChain": [{
		"serviceName": "ServiceName1",
		"serviceVersion": "1.0.0"
	}]
}

Two parents with no children service

{
	"choreographyName": "Choreo_2Parents_NoChildren",
	"stepChain": [{
			"serviceName": "testService1",
			"serviceVersion": "2.0.0"
		},
		{
			"serviceName": "testService2",
			"serviceVersion": "1.0.0"
		}
	]
}

One parent with one child service

{
	"choreographyName": "Choreo_OneParent_OneChild",
	"stepChain": [{
		"serviceName": "ServiceName1",
		"serviceVersion": "1.0.0",
		"child": [{
			"serviceName": "ServiceName2",
			"serviceVersion": "1.0.0",
			"child": [{
				"serviceName": "ServiceName3",
				"serviceVersion": "1.0.0"
			}]
		}]
	}]
}

One parent with two children service

{
	"choreographyName": "Choreo_OneParent_TwoChildren",
	"stepChain": [
		{
			"serviceName": "ServiceName1",
			"serviceVersion": "1.0.0",
			"child": [
				{
					"serviceName": "ServiceName2",
					"serviceVersion": "2.0.0"
				},
				{
					"serviceName": "ServiceName3",
					"serviceVersion": "3.0.0"
				}
			]
		}
	]
}