HTTP Forwarding Filter

How to use the Xyna HTTPForwarding Filter to publish a service

Task: An existing workflow in the Xyna Factory shall be published as a REST Interface

When you have a workflow in Xyna, which is used internally and has not yet a public interface, there are different possibilities to publish this workflow, so that it can be called from outside the factory via a HTTP REST call.

One of those possibilities is the usage of the Xyna "HTTP Forwarding Filter", which is delivered as a part of the http application.

Prerequisites:

1. The http application is installed. In this tutorial the version 1.2.5 of the http application is used
2. The workflow, that shall be published, is present in the system and is tested in a local environment. In this tutorial we use the Workflow "Get Webpage". This wokflow gets a filename as an input and delivers the contents of the locally stored file as a string. We assume, that the workflow is deployed in a workspace named "Webpage_Impl_WS".

The following steps do the job:

1. Create Trigger Instance using the existing HTTP Trigger, delivered with Xyna:

   ./xynafactory.sh deploytrigger -workspaceName 'Webpage_Impl_WS' -triggerName Http -triggerInstanceName Http_OAS4220 -startParameters port=4220

   This command creates a trigger instance with name "Http_OAS4220", which listens to the port 4220. This trigger instance is deployed in the same workspace as the workflow.

Alternatively, you can create the trigger instance via the GUI (Factory Manager / Trigger):

2. Create Filter Instance using the existing HTTPForwarding Filter, delivered with Xyna:

   ./xynafactory.sh deployfilter -filterName HTTPForwardingFilter -workspaceName Webpage_Impl_WS -triggerInstanceName OASEntry_4220 -filterInstanceName Webpage_Forwarding

   This command creates a filter instance with name "Webpage_Forwarding", which is connected to the trigger instance "OASEntry_4220" we created in step 1. This trigger instance is deployed in the same workspace as the workflow.

3. Create a dispatcher workflow, which can be called by the new filter instance. The tasks of the workflow (in our case named "Get Webpage Dispatcher") are:

   1. Fulfill the signature which is needed by the filter instance.
      1. Input-Parameters: xact.http.URL-path, base.host, base.Port, xact.http.enums.httpmethods.HTTPMethod, xact.http.Header, xact.templates.Document
      2. Output-Parameters: xact.templates.Document, xact.http.Header, xact.http.enums.statuscode.HTTPStatusCode
   2. Call the workflow you want to publish

4. Create the ordertype in the Factory Manager, which maps the incoming requests to the dispatcher workflow:

   • Name: xact.http.ProcessHTTPRequest.port=4220 (port value must be the value used for the trigger instance)
   • Execution Destination: Full qualified name of the dispatcher workflow (the one created in step 3)

5. Test the filter: You can test your filter setup using cURL via the example command: curl --location 'http://<your server address>/hello1.html'