Need Ideas for creating and using Custom Business Object

Question

Hello Guys,
I am developing an application which uses a Request->Approve->Create approach for creating Purchase documents.
Now I am a little puzzled about how to make use of the Business Object BUS2014.
The application I am developing has its own unique 'Request Number'  (say REQID)  which will point to the Request for Creation of a purchase order.
Whenever a Request is created (from a Z-Tcode) a workflow needs to be initiated and it has to be sent to the approver.
The Purchase Document will be created once the approver approves.
Now my confusion here is, if I use BUS2014, the object will be instantiated only during the final step of the workflow. But I need an instance during the beginning of the Requestor ->Approver negotiations as I am playing with events. These events needs an Object_key.
How should I proceed here?
Should I create a new logical Business Object like ZPOREQ where I have the above mentioned REQID as the key?
And should I have an attribute of type BUS2014 inside the custom BO?
How will I make use of the methods like BUS2014.Create etc which I may need to create the purchase document?
Any small direction will be a huge help for me to get used to this wilderness.

Answer 1

Hi,
You should continue with the ABAP class idea. The business objects are kind of "obsolete" already, and if there is a need to create a new "object", ABAP classes are the way to go. Business objects are still useful, but I normally use them only when an existing standard business object fulfills the requirements (possibly with slight additions) which is almost never. 
From my point of view you can use the existing class. Depending on the circumstances I normally have just one class that I use for both workflow and the possible other functionality that is required, but you have to understand that I have this goal in my mind already when starting the development process. As your class most probably has many useful features already (such as you have the header and item data as attributes etc. (if I understood correctly?), these are also useful in in workflow (class attributes will be available in WF container etc.). 
If you are hesitant to use the same class directly in your workflow, you could also create a new class ZCL_REQUEST_FOR_WF (with the workflow interface), and then simply add your existing class ZCL_WF_REQUEST as an attribute to this new class. Then this new workflow class could include the pure workflow stuff, and your existing class the non-workflow stuff. But this most probably will not make much sense - just implement the if_workflow interface in your existing class (this is just one possibility that you might consider.)
Regards,
Karri