Work flow..
Work flow sending data from one personnel to nother or from one transaction to another.Workflow will be triggered mainly when a transaction is saved or some even occures in any transaction. When an even t occurs all the data will be bundled and sent to a Business object. From this business object we can manipulate the data, change according to our requirements and trigger a workflow.

A business object is basically object oriented repository in SAP.
Components of Business object
it contains business object type, interface type and components such as methods , attributes and events.,

when a workflow is triggered it starts from the transaction. when a user saves the transaction,the data goes to a business object send the data out as event and methods will genearte the data and send it to work flow. most of the sap transaction have business objects. but we can also do some customization to get new business objects and we can do with out business objects also by using some sap function modules..
Scenario:
For the scenario we have to first look if there is any standard workflow is available, if available we can use it and if not we have to build one.
ex: Work flow for sap hr system.
when an employee is hired or rehired, a supervisor will be informed through an email.
Here in this scenario we are using a sap smart form as a email that has to be sent to the supervisor. we can send a simple mail but why we are using a smart form is ,
the mail that goes to a supervisor should ave a standard format. for this purpose we are using a smart form.
In sap hr for hiring we use the transaction PA40.
in the transaction PA40 give the personnel number and Select the HIRE action and then execute.
The sample screen looks like this PA40 transaction

Basically this is the screen for employee hiring action in HR i.e PA40. This hiring action is a process of many screens and they are called infotypes in HR. Just because we have taken Work flow example in HR..some people may get confused like my friend Marella...who is in SD and MM module. (thanks to him for helping in building this website). so come to the point.here each screen is called as infotype. not we have to fill all the necessary fields in every screen to complete the hiring action in PA40.Fill the personnel number and select the HIring as shown in the screen left side and click execute button. By clicking you will be taken to another screen i.e infotype "0000". And you have to fill the necessary fields there. Now after saving you will be taken to infotype 0002 screen.

This is infotype 0000. give all the required fields and save. then you will be taken to next screen infotype 0002

This is infotype 0002 screen where you will have to fill the values. affter saving here you will be taken to next screen infotype 0001.

This infotype 0001 screen. Give all the required values and save. this screen is where exactly where the workflow is needed o be triggered.Here after giving the contract data and the moemnt you save, the work flow should be triggered.Now lets discuss little bit about the architecture here. The moment we save in this third screen, all the data i.e what ever we filled in the 3 screens (0000, 0002, 0001) should be bundled into a business object .I am sure you understand about this point. All the 3 screens data will be saved into a business object. Now we need to know which business object it will be stored. And have to see the data we have just filled.Now we will go from this screen and see how this business object data is sent to work flow..how we have to configure this scenario.

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