Software AG Products 10.11 | Using API Gateway | Policies | System-defined Stages and Policies | Response Processing | Invoke webMethods IS
 
Invoke webMethods IS
This policy processes the native API’s response messages into the format required by the application, before API Gateway returns the responses to the application.
If Comply to IS Spec parameter is configured as true, API Gateway invokes the IS Service with IS specification in the path pub.apigateway.invokeISService.specifications:ResponseSpec (for Response Processing)
The following are the input and output parameters for REST, SOAP, and WebSocket APIs as specified in the above IS Specification. Input parameters can be used to access the existing values of the response while output parameters can be used to modify/write the values to the response.
Parameter name
Description
Input parameters
headers
Headers in response.
Data type: Document
payload
Payload of the response.
Data type: String
payloadObject
The payload for binary content types like multi-part / form-data.
Data type: Object
statusCode
Status code of the response.
Data type: String
statusMessage
Status message of the response.
Data type: String
MessageContext
The message context object of the response.
Data type: Object
apiName
Name of the API invoked by the response.
Data type: String
requestUrl
URL of the response.
Data type: String
ipInfo
Contains IP information of the response.
Data type: Document
websocketInfo
Websocket related information of the response.
Data type: Document
correlationID
Correlation ID of the request/response. This is unique and same for a request and response.
Data type: String
customFieldsMap
Custom transactional fields can be added to the transactional events using this field. For more information, see Adding Custom Fields to Transactional Events section.
Data type: Document
Output parameters
headers
Headers in response.
Data type: Document
payload
Payload of the response.
Data type: String
payloadObject
The payload for binary content types like multi-part / form-data.
Data type: Object
statusCode
Status code of the response.
Data type: String
statusMessage
Status message of the response.
Data type: String
MessageContext
The message context object of the response.
Data type: Object
customFieldsMap
Custom transactional fields can be added to the transactional events using this field. For more information, see Adding Custom Fields to Transactional Events section.
Data type: Document
Note: 
*For SOAP to REST APIS, the payload contains the transformed JSON response.
*Payload transformation does not happen automatically for content-type transformation. When you change the content type, ensure to do payload transformation also as part of IS Service.
*When Comply to IS spec is true, you can change the values of headers, query, payload, and so on, programatically using Message Context, as well as using the pipeline variables given. Software AG recommends you not to change those values directly in Message Context, as the values in output pipeline variables are written to Message Context after the invocation of IS Service.
If Comply to IS Spec parameter is set to false, API Gateway invokes the IS Service with the same input and output parameters supported in 10.1 and the earlier versions::
*proxy.name
*JSONRESTContentString (REST only)
*SOAPEnvelope (SOAP only)
*EnvelopeString (SOAP only)
The table lists the properties that you can specify for this policy:
Property
Description
Invoke webMethods Integration Server Service
Add invoke webMethods Integration Server service
Specifies the webMethods IS service to be invoked to process the response messages and the authentication mode for the IS service.
Provide the following information:
*webMethods IS Service. Specify the webMethods IS service to be invoked to pre-process the response messages.
The webMethods IS service must be running on the same Integration Server as API Gateway
Note:
If an exception occurs when invoking the webMethods IS service, by default API Gateway displays the status code as 500 and error message as Internal Server Error.
You can set custom status code and error message by setting the following properties in the message context of the webMethods IS service:
*service.exception.status.code
*service.exception.status.message
The sample code is given below:

IDataCursor idc = pipeline.getCursor();
MessageContext context = (MessageContext)IDataUtil.get(idc,"MessageContext");
if(context != null)
{
context.setProperty("service.exception.status.code", 404);
context.setProperty("service.exception.status.message", "Object Not Found");
throw new ServiceException();
}
Note:
If ServiceException or FlowException occurs when invoking webMethods IS Service, the message given in the exception is displayed to the client. If any other exception occurs, a generic error message is displayed to the client.
*Run as User. Specifies the authentication mode to invoke the IS service. If this field is left blank the incoming credentials of the user, identified by API Gateway, are used to authenticate and invoke the IS service. You can also specify a particular user, you want API Gateway to invoke the IS service.
Note:
It is the responsibility of the user who activates the API to review the value configured in Run as User field to avoid misuse of this configuration.
*Comply to IS Spec. Mark this as true if you want the input and the output parameters to comply to the IS Spec present in pub.apigateway.invokeISService.specifications folder in wmAPIGateway package.
Note:Software AG recommends users to configure the policy with Comply to IS Spec as true, as you can read or change the values of headers, and so on, without having to read from or write to the message context.
webMethods IS Service alias
Specifies the webMethods IS service alias used to invoke the webMethods IS service to pre-process the response messages.
Start typing the webMethods alias name, select the alias from the type-ahead search results displayed and click to add one or more aliases.
You can use the delete icon to delete the added aliases from the list.
Adding Custom Fields to Transactional Events
This section explains you how to add custom fields to the transactional events.
1. Create webMethods IS service by specifying the pub.apigateway.utils:customFieldInTransactionEventSpec as a specification reference.
2. In the webMethods IS service, set the required custom fields in the customFieldsMap output variable.
3. Once when customFieldsMap gets created, the custom fields will be available in the transactional events.
4. Invoke the API with the Invoke webMethods IS policy.
Note:
You can also add the custom fields to the transactional events from API Gateway by configuring the customTransactionFields.FIELD_NAME custom variable in the Custom Extension policy. For more details, see How Do I Define a Custom Variable?.