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Requirement

Title

Message exchange pattern

Identifier

SWIM-SERV-017

Requirement

A service description shall include the message exchange pattern used by the service.

Rationale

The message exchange pattern helps understanding how the information interaction with the service works.

Verification

Completeness: Verify that the information is included.

Consistency: Verify that the information is consistent with the selected service interface binding.

Correctness: Not Applicable.

Examples/Notes

Note: Typical message exchange patterns (as from the SWIM Technical Infrastructure Yellow Profile [RD 3]):

  • Request/Reply (synchronous or asynchronous);
  • Publish/Subscribe (Push or Pull);
  • One Way (also known as Fire and Forget).

Level of Implementation

Mandatory

Guidance

Understanding message exchange patterns

The document MEP identification, developed in the SWIM-TEC community, provides information on the various notions of message exchange pattern (MEP). 

  • it introduces the concept of MEP
  • it explains the difference between primitive MEPs and application MEPs.
  • it provides the semantic of each MEP in text and diagram


Info

This requirement refers to the application message exchange pattern used by the service.

Examples

See the Message exchange pattern section within the Donlon TOBT Setting Service Description.

Guidance for JSON service description

tentative JSON Guidance

info

Guidance on the full set of categories as available within the European SWIM Registry is provided at requirement SWIM-REG-0004 Service categorization.

Schema

The guidance concerns JSON Schema v0.0.3 (see Schema releases).

 Schema excerpt [+]
		"serviceCategorisation":
				{
					"description" : "A taxonomy used to classify a service by the type of service provided or by some other technological or architectural solution. [SWIM-SERV-009]",
					"$ref" : "#/definitions/ServiceCategorisation"
				}


		"ServiceCategorisation" : 
		{
			"description" : "A taxonomy used to classify a service by the type of service provided or by some other technological or architectural solution. [SWIM-SERV-009]",
			"type": "object",
			"additionalProperties": false,
			"required": ["serviceType", "lifeCycleStage", "businessActivityType", "intendedConsumer", "informationCategory", "applicationMessageExchangePattern"],
			"properties":
			{
				"applicationMessageExchangePattern":
				{
					"description" : "The type of Application MEP. [SWIM-SERV-017]",
					"type" : "array",
					"items" : { "$ref":"#/definitions/CodeApplicationMessageExchangePatternType" },
					"minItems": 1
				},
		},


		"CodeApplicationMessageExchangePatternType" : 
		{
			"description" : "A code listing types of application message exchange patterns.\n",
			"type": "string",
			"enum":
			[
				"ASYNCHRONOUS_REQUEST_REPLY",
				"BROKERED_PUBLISH_SUBSCRIBE_WITH_PUSH_MECHANISM",
				"FAN_OUT",
				"ONE_WAY",
				"PUBLISH_SUBSCRIBE",
				"PUBLISH_SUBSCRIBE_WITH_PULL_MECHANISM",
				"PUBLISH_SUBSCRIBE_WITH_PUSH_MECHANISM",
				"REQUEST_REPLY",
				"SYNCHRONOUS_REQUEST_REPLY"
			]
		},
 Rules [+]

Rules expressed for the cases as defined in Registry URD.

caserules
COMPLIANTmandatory, 1 or more values
CANDIDATEsame
DEFINITIONsame

Guidance

Select one or more values in field applicationMessageExchangePattern, within field serviceCategorisation.

Enumerated values

CodeApplicationMessageExchangePatternType
REQUEST_REPLY An application MEP consisting of a consumer sending a request to an information service, the service then executing the request and providing a reply to the consumer.
ONE_WAY An application MEP consisting of a consumer sending a message to an information service without any requisite response from the information service.
PUBLISH_SUBSCRIBE An application MEP consisting of a consumer sending a subscription request to an information service, the service then providing the consumer with means to access the subscribed information.
FAN_OUT An application MEP consisting of a consumer sending sequentially a message to multiple information service according to the One-Way application MEP.
SYNCHRONOUS_REQUEST_REPLY A Request/Reply application MEP requiring that the consumer wait for the information service to provide a response, and is unable to send/receive any other requests/responses until the initial response is received.
ASYNCHRONOUS_REQUEST_REPLY A Request/Reply application MEP that does not restrict the consumer from completing other operations while waiting for the information service to respond.
PUBLISH_SUBSCRIBE_WITH_PUSH_MECHANISM A Publish/Subscribe pattern whereby the information service sends necessary updates (publish) to the consumer, in accordance with the subscription.
PUBLISH_SUBSCRIBE_WITH_PULL_MECHANISM A Publish/Subscribe pattern whereby the information service keeps necessary updates available to the consumer, in accordance with the subscription.
BROKERED_PUBLISH_SUBSCRIBE_WITH_PUSH_MECHANISM A Publish/Subscribe pattern with push mechanism introducing a layer of decoupling between the publisher and subscribers by means of a broker.

Example

 "serviceCategorisation": {
     
     "applicationMessageExchangePattern": [
        "SYNCHRONOUS_REQUEST_REPLY"
      ],
     
      }

A complete JSON example is available in page JSON example - Donlon TOBT Setting service description.

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