Leveraging Oracle Workflow for Declarative PageFlow

This blog post contributed by Dilbagh Singh.

Oracle Workflow can be leveraged in Oracle Applications Framework for
designing declarative Page Flow, which is used to handle conditional
navigation rules.This is a better way to handle page navigations if you
would want to avoid static, complex logic in the page controllers to
handle different navigation scenarios. This requires a user to create a
Pageflow workflow definition which is associated with the OA Framework
based pages. Then there are certain APIs which are used in transition
flow of the workflow. I would like to focus on creating a Workflow
Definition for the page flow and how to interact with it as the
transaction proceeds.

1. Create the OA Framework pages

Create the OA Framework pages you would want the page flow to
consist of.

2. Design the Workflow Definition for the Page Flow

Define the Workflow in the workflow builder following the below
mentioned guidelines:

• Add a function activity for each page in the
  transaction. For each activity, decide whether to:


• Associate the result with this activity (for conditional
  navigation) OR


• Explicitly mark the activity as blocked by associating a Blocking
  Function (wf_standard.block), a PLSQL function with it


• When the Workflow Engine encounters a blocking activity it stops
  and waits for some sub-process or external entity to provide the
  information it needs to proceed. So, with the mapping between
  transaction pages and the blocking activities in the Workflow, you can
  query the activity data to find out what page ought to be rendered.


• Add a FORM attribute to each page-related blocking activity. The
  FORM attribute would have a value which specifies the next page to be
  traversed.

• You can start the page flow from a OAF page directly
  or upon triggered by some event or can start it from a static page by
  using the API OANavigation which provides createProcess() and
  startProcess()


• You can then transition through the workflow by using getNextPage()
  from OANavigation API. There are different overloaded getNextPage APIs
  for transitioning through workflow, transitioning to next page, resuming
  a saved transaction etc. You can get the code snippets in the OAF Dev
  guide.

• Since the Workflow transaction holds an independent local JDBC
  connection, you must override the OADBTransaction.beforePoolCheckin()
  method in your root UI application module and call
  getDBTransaction.clearWorkflowInfo() to release the connection.

1. Workflow-based page flows automatically support browser Back button
   navigation at the Workflow technology layer. Whenever user moves
   between the pages using browser Back button and resubmits, the workflow
   rewinds itself to the appropriate blocking activity so it stays in synch
   with the user’s current navigation position.


2. Workflow Page Flow can be used with Train and Navigator bar in a
   page, which the traditional ‘Destination Function’ based approach does
   not support.


3. For the most part, you handle application errors in your
   Workflow-based page flows the same way that you do in any other context.
   That said, however, you need to consider the possibility that the user
   might fix mistakes and resubmit the form whenever you introduce workflow
   code.