Task Status

This page is part of the ongoing SWIM communities of interest discussions. The content is working material. It should not be treated as final as it is still subject to review, comment and change.

Introduction

Service design is a step in the service orientation process detailed on the SWIM reference website (https://reference.swim.aero/knowledge/service-orientation-process.html#design). One outcome is a service model (service interface(s), service operation(s), service behaviour). This leads to consideration on how to name things.

The following documents will help.

In general:

The noun/role should be as clear as possible.
The verb should be from an agreed list (of examples).

Naming conventions

The following section shows how the names would appear in a service definition.

SWIM-DEFN-140 Service functions

The functionality name could be harmonised.

The functionality expresses the business view of the service. Natural language is preferred.

Example of SWIM-SERV-140 using Service Metadata Schema

"generalDescription": {
 "functionality": [{
  "name": "Provide Turbulence Forecast Information",
  "description": "A detailed and product-specific description on the delivered product.",
  "realWorldEffect": "Information is provided continually; the service consumer gets the subscribed data."
 }, {
  "name": "Meteorological Forecast Provision",
  "description": "...",
  "realWorldEffect": "..."
 }]
}

SWIM-DEFN-240 Service interfaces

Name and description could be harmonised e.g. AMQP Notification, AMQP Subscription, WFS Request..

A service may contain multiple interfaces. Some of these may be private or at least interfaces for specific purposes, e.g. Monitoring or Reporting interfaces. Should they be documented?

SWIM-SERV-240

Note: To improve readability across service descriptions, it is best practice to apply the following conventions for a service interface name

be represented using UpperCamelCase; and
use the <noun> <role> pattern where <noun> is a topic related to the service and <role> describes the roles in a composition/interaction sequence, based on the Message Exchange Pattern that is used.

Example service interface names: FlightPlanCoordinator, FlightPlanSubmitter, ForecastProvider, ForecastConsumer, ClearanceRequester, ClearanceManager, PreDepartureSequencer, FlightInformationPublisher, AlertListener.

It is best to avoid mention of a broker. Indeed, a broker is not necessary when using AMQP.

Examples based on this from the SWIM Registry:

TurbulenceForecastPublisher for https://eur-registry.swim.aero/services/dwd-turbulence-amqp-10
ArrivalSequenceInformationPublisher for https://eur-registry.swim.aero/services/dsna-arrivalsequencedistribution-service-v11 (not AMQP but shows the same pattern for names).
NowCastSatRequest for https://eur-registry.swim.aero/services/dwd-nowcastsat-wfs-10

As far as WFS is concerned, what are the roles?

Request...

As far as AMQP is concerned, what are the roles?

Publisher, Queue, Message...

SWIM-DEFN-270 Service operations

Consider a controlled vocabulary of verbs for names.

SWIM-SERV-270

Note: To improve readability across service descriptions, it is best practice to apply following conventions for a service operation name:

include a verb and a noun; and
be represented using lowerCamelCase.

Example service operation names: getAlerts; requestTrajectoryAnalysis; publishAirportMETInducedCapacity; setCoordinationAndTransferData; proposeARESDeActivation; setTargetOffBlockTime.

When you are a consumer, you can subscribe to an existing topic(exchange) on an exposed endpoint or connect to a specific endpoint (which is user specific).

Depending on whether to include business logic, operations could be:

publishMessageTopic
publishMessageQueue

or with some business logic:

publishTurbulenceForecastMessageTopic
publishTurbulenceForecastMessageQueue

Note that there is no need to document operations if a standardised implementation is used. See Standardised Implementations for more information.

Categorisation

SWIM-DEFN-100 Service categories

The following example shows how to add a service categorisation for a Web Feature Service.

Example of SWIM-SERV-100 using Service Metadata Schema

"serviceCategorisation": {
 "other": [{
  "name": "SERVICE_TYPE",
  "value": "FEATURE_ACCESS_SERVICE",
  "categorisationScheme": {
   "url": "http://reference.swim.aero/information-services/service-categories/CodeServiceType"
  }
 }]
}

To describe an implemented service that uses AMQP 1.0 in an harmonised way it would be good to visit the categorisation schemes and indicate which of the elements in the relevant schemes are expected to be used. For instance: CodeApplicationMessageExchangePatternType.PUBLISH_SUBSCRIBE etc..in general would expect on this page also categorisation related information.

Service Design Activities