Question: Is it mandatory to specify Business Object on a Workflow?Answer: No, Business Object needs to specified only when there is need to use Siebel Operation in Workflow.
Question: What is the difference between Expression business component and Filter business component in Siebel Operation?Answer: These business components fields are used in Siebel Operation when search spec is built by referencing another business component field.
For Example: To find Account records where Account Id is specified in Contact's Account Id field, expression will be created like :
"[Id] = [Account Id]"And Filter Business Component will be set as : Account and Expression Business will be set as Contact. Thus it will be evaluated as :
"[Account.Id] = [Contact.Account Id]"
read more on :
How to create Siebel Operation Expression
Bookshelf: Defining Siebel Operation Search Spec