You may have a need to be proactively notified whenever a particular business object is changed. E.g. If I own a particular Sales Order and I want to ensure that I am immediately made aware of any changes to it then I can do the following to "subscribe" to the sales order changes:
Using transaction SU3 make sure that you have your default parameter for SD_SWU_ACTIVE = 'X' as shown below. This will enable the Generic Object Services (GOS) button to appear on your sales order transactions.
Subscribing to Sales Order changes
In transaction VA02 you can select the GOS object menu My Objects -> Subscribe / Cancel Object as shown below.
You are now subscribed to any changes to that particular Sales Order as shown below.
How does it work?
Use transaction SWETYPV, as shown below, to see that the Object BUS2032 (Sales Order) and event CHANGED is linked to receiver "SUBSCRIBE". This is standard SAP functionality and should not have to be configured (although it may need to activated).
After making a change to a subscribed sales order you can technically review the event that was triggered using transaction SWELS. In the diagram shown below you can see how the CHANGED event was triggered for BUS2032 for receiver SUBSCRIBE.