Once the workflow is engaged in the API subscription scenario, user's request for a new subscription will go into a temporary 'On Hold' state where in which it will remain until approved or rejected by the Workflow Administrator.
To enable API Subscription workflow you will need to change theSubscriptionCreation executor from "SubscriptionCreationSimpleWorkflowExecutor" to "SubscriptionCreationWSWorkflowExecutor" in the <AM_HOME>/repository/conf/api-manager.xml (see below).
When making this change you need to specify the service endpoint at which the Workflow Engine is hosted along with the credentials required to access said service via Basic Authentication (i.e. username and password).
Invoking the Workflow Engine
Once the SubscriptionCreationSimpleWorkflowExecutor is engaged, whenever a user tries to subscribe to an API with an application, in the API Manager Store, a request of the following format will be sent to the Workflow Endpoint (You may refer the wsdl here when implementing your custom Workflow Service) specified under "serviceEndpoint" in the API Manager.xml.
A detailed explanation of each property is as follows.
|Name of the API to which subscription is requested|
|Version of the API, user wishes to subscribe to|
|Context on which the requested API is to be accessed on|
|Provider of said API|
|Name of the User requesting the subscription|
|Name of the application through which the user wishes to subscribe to the API|
|Thorrtling tier specified for the application|
|workflowExternalRef||The unique reference against which a workflow will be tracked. This will need to be sent back from the Workflow Engine to API Manager at the time of workflow completion.|
At the time of workflow completion, this is URL to which the "Workflow completed" request will be sent to by the Workflow Engine. This property is configured under the "callBackURL" property in the api-manager.xml
(Can be either a SOAP or REST endpoint)
In addition to invoking the Workflow Engine, at the time of executing a Workflow an entry will be added to the AM_WORKFLOWS table in the API Manager Database, indicating the workflow status and workflow external reference along with a host of other information. This entry in turn will be used to track the progress of the workflow throughout its lifecycle. At a given time, the status of a workflow can be either 'CREATED', APPROVED' or 'REJECTED'. 'CREATED' is the default status of a workflow, it will get promoted to either 'APPROVED' or 'REJECTED' state based on the response from Workflow Engine.