Adding an API Subscription Workflow

This section explains how to attach a custom workflow to the API subscription operation in the API Manager. First, see Workflow Extensions for information on different types of workflows executors.

Attaching a custom workflow to API subscription enables you to add throttling tiers to an API that consumers cannot choose at the time of subscribing. Only admins can set these tiers to APIs. It also allows you to restrict API consumers to only subscribe to sandbox, and then go through an approval process to go to the next level of subscription.

Before you begin, if you have changed the API Manager's default user and role, make sure you do the following changes:

Give the correct credentials in the <BPS_HOME>/repository/conf/epr files.
Change the credentials of the workflow configurations in the registry resource _system/governance/apimgt/applicationdata/workflow-extensions.xml.
Point the database that has the API Manager user permissions to BPS.
Share any LDAPs, if exist.
Change the .ht file of the relevant human task.
Change the allowedRoles parameter in the <APIM_HOME>/repository/deployment/server/jaggeryapps/admin-dashboard/site/conf/site.json file.

Configuring the Business Process Server

Download WSO2 Business Process Server.
Set an offset of 2 to the default BPS port in <BPS_HOME>/repository/conf/carbon.xml file. This prevents port conflicts that occur when you start more than one WSO2 product on the same server. Also see Changing the Default Ports with Offset.
<Offset>2</Offset>
Copy the following from <APIM_HOME>/business-processes/epr to <BPS_HOME>/repository/conf/epr folder. If the <BPS_HOME>/repository/conf/epr folder is not there, please create it.
- SubscriptionService.epr
- SubscriptionCallbackService.epr
Start the BPS server and log in to its management console (https://<Server Host>:9443+<port offset>/carbon).
Select Add under Processes menu and upload the <APIM_HOME>/business-processes/subscription-creation/BPEL/SubscriptionApprovalWorkFlowProcess_1.0.0.zip file to BPS. This is the business process archive file.
Select Add under the Human Tasks menu and upload <APIM_HOME>/business-processes/subscription-creation/HumanTask/SubscriptionsApprovalTask-1.0.0.zip to BPS. This is the human task archived file.

Engaging the WS Workflow Executor in the API Manager

First, enable the API subscription workflow.

Log in to APIM admin console (https://<Server Host>:9443/carbon) and select Browse under Resources.
Go to /_system/governance/apimgt/applicationdata/workflow-extensions.xml resource, disable the Simple Workflow Executor and enable WS Workflow Executor. Also specify the service endpoint where the workflow engine is hosted and the credentials required to access the said service via basic authentication (i.e., username/password based authentication).
<WorkFlowExtensions> ... <SubscriptionCreation executor="org.wso2.carbon.apimgt.impl.workflow.SubscriptionCreationWSWorkflowExecutor"> <Property name="serviceEndpoint">http://localhost:9765/services/SubscriptionApprovalWorkFlowProcess/</Property> <Property name="username">admin</Property> <Property name="password">admin</Property> <Property name="callbackURL">https://localhost:8243/services/WorkflowCallbackService</Property> </SubscriptionCreation> ... </WorkFlowExtensions>
The application creation WS Workflow Executor is now engaged.
Go to the API Store Web interface and subscribe to an API.
It invokes the API subscription process and creates a Human Task instance that holds the execution of the BPEL until some action is performed on it.
Note the message that appears if the BPEL is invoked correctly, saying that the request is successfully submitted.
Log in to the Admin Dashboard Web application (https://<Server Host>:9443/admin-dashboard), list all the tasks for API subscription and approve the task. It resumes the BPEL process and completes the API subscription.
Go back to the API Store and see that the user is now subscribed to the API.
Whenever a user tries to subscribe to an API, a request of the following format is sent to the workflow endpoint:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"xmlns:wor="http://workflow.subscription.apimgt.carbon.wso2.org"> <soapenv:Header/> <soapenv:Body> <wor:createSubscription> <wor:apiName>sampleAPI</wor:apiName> <wor:apiVersion>1.0.0</wor:apiVersion> <wor:apiContext>/sample</wor:apiContext> <wor:apiProvider>admin</wor:apiProvider> <wor:subscriber>subscriber1</wor:subscriber> <wor:applicationName>application1</wor:applicationName> <wor:tierName>gold</wor:tierName> <wor:workflowExternalRef></wor:workflowExternalRef> <wor:callBackURL>?</wor:callBackURL> </wor:createSubscription> </soapenv:Body> </soapenv:Envelope>
Elements of the above configuration are described below: