SAP EDI Architecture (Inbound and Outbound process)

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　　The SAP EDI process comprises two distinct processes.

• Outbound process
  
• Inbound process
  

The Outbound Process
　　The outbound process sends documents from the SAP system to a business partner (vendor, customer, and bank). The outbound process consists of six steps.
　　The application document is created. The first step in the outbound process involves creating an application document such as a purchase order or sales order and saving it in the database tables. This step is no different from the way in which these documents are normally created. It is the following steps that have relevance to EDI. The document is created and leaves some hooks for the EDI process to begin.
　　The IDoc is generated. The application document just created is now formatted to an IDoc format.At this point you can think of IDoc as yet another format in which the application document has been represented. A document in an IDoc format is suitable for processing by EDI components.
　　The IDoc is transferred from SAP to the operating system layer. The IDoc created in the above step resides in the SAP database repository. This IDoc document must be passed down to the operating system layer for processing by the EDI subsystem. Now the IDoc is transferred to the operating system as a text file. The document is still in an IDoc format. The only difference is the medium of storage.
　　The IDoc is converted to EDI standards. The IDoc format is an SAP proprietary format. For EDI purposes, the document in IDoc format has to be converted into an EDI standard format. Third-party software called a translator carries out the transformation process and reports status back to the SAP system. SAP refers to these translators as EDI subsystem or other middleware translltor like SAP XI/PI. SAP takes no responsibility for translation. Thus, from SAP's perspective, after the IDoc is delivered to the subsystem or middleware, SAP does not have control over the process, but it maintains the status reported by the EDI subsystem.
　　The EDI document is transmitted to the business partner. After the document is converted to an EDI standard format, it is transmitted to a trading partner based on the partner's EDI settings. This step is not part of the SAP EDI architecture, but is mentioned here to describe the complete process from a business perspective.
　　The EDI subsystem reports status to SAP. When an IDoc is under the control of the EDI subsystem, the subsystem can optionally report the state of processing at various milestones back to the SAP system. This mechanism is always recommended because it provides complete visibility of the process from within SAP, and the user does not have to be involved with the intricacies of the EDI subsystem.
The Inbound Process
　　The inbound process simply reverses the steps of the outbound process. The inbound process receives an EDI document (such as a purchase order response, sales order, or payment information) from a business partner (such as a vendor, a customer, or a bank) and creates SAP documents from it.
　　The inbound process consists of five steps.
　　The EDI transmission is received. EDI documents are received from a business partner via the VAN or AS2. These documents are in one of the EDI standard formats. The documents are deposited in a common repository for the subsystem. This part of the process is not part of the SAP EDI architecture.
　　The EDI document is converted into an IDoc. The EDI-specific headers and trailers are stripped off, and the document is converted into an IDoc format suitable for SAP applications. The process is carried out at the EDI subsystem or middleware level.
　　The IDoc is transferred to the SAP layer. The IDoc created in the above step is stored in a text file at the operating system layer. The subsystem starts an inbound program in the SAP layer. This program reads the IDoc file and creates an IDoc in the SAP repository for further processing.
　　The application document is created. The IDoc received from the subsystem is passed to a posting program. This program creates an application document such as a sales order, purchase order acknowledgment, invoice, or shipment notice.
　　The application document can be viewed. The application document created via EDI is the same as any document created manually in the system: The document can be viewed using standard application transactions. For example, if an incoming sales order was created via EDI, you could view the sales order document via transaction VA03.