B2B communication using PI

Question

Hi all,
I want to know what exactly is the meaning of B2B communication and A2A communication.How are both of them different?
How exactly does the concept of "Party" help to establish B2B communication.
Many Thanks,
Neha

Answer 1

Hi Neha,
You already have the best answers from the Gurus. Only to add to answer the second part of your question,
"How exactly does the concept of "Party" help to establish B2B communication."
In a scenario Party object designates an Organization or a similar entity (Business partners/customers or the Home Organization) taking part in the scenario.
Using Parties in a B2B scenario in XI helps to define the logical scenario between the transacting parties........where you use the Services under Parties.
While in A2A you should use Service without party, as the transaction takes place between Business (Logical) Systems defined within your System Landscape (SLD).
Now how technically the Party object helps to establish B2B communication...............
While configuring IDoc scenarios and the IDoc partners for these transactions are defined as Vendors (LI) or Customers (KU) in the Backend R/3 systems,
then the Inbound IDoc adapter resolves the Sender/Receiver information (SNDPRN, SNDPRT, RCVPRT, RCVPRN) in the IDoc control header to a specific Party object in the configuration during Normalization, using Party Identifiers.
And reversely the Outbound Idoc adapter resolves the Party objects used in XI scenario into the Backend R/3 system's Idoc partner while creating the Idoc Control header Information.
Also the Party Identifiers (Alternative Identifiers) are used to convert the Party names used in XI scenario to Multiple globally-recognized identifiers for Companies
(Such as DUN numbers or EAN codes) - which directly relates to (facilitates) a physical cross-company process/transaction - in the message header.
Some useful excerpts from help.sap.com
A communication party (party for short) represents a larger unit, which is involved in a collaborative process.
Using a communication party, you generally address a company within a cross-company process. 
You can assign a communication party one or more services to address it as the sender or receiver of messages.
Alternative identifiers are used as follows at runtime:
·        Inbound Processing:
If a message from an external party contains an identifier for a company in the message header, the identifier is mapped to the name of the internal party (normalization).
Only then can the relevant configuration objects required for the message to be processed further be found and analyzed in the Integration Directory.
·        Outbound Processing:
The internal party name of an outbound message is mapped to the identifiers to be used (in accordance with the configuration settings).
The external receiver then receives a message that contains the externally-valid identifier in the message header (denormalization).
Wish you the best in developing your first B2B scenarios
Regards,
Suddha
Edited by: Suddhasatta Guha on Aug 19, 2008 2:20 PM
Edited by: Suddhasatta Guha on Aug 19, 2008 2:24 PM