SAP ALE IDocs interview questions and answers Part 1

ALE IDocs in SAP

ALE IDocs in SAP is a lot about configuration and a lot about Tcodes . So if you have worked on at least one end to end scenario in ALE IDocs in SAP , you probably already have answers to a lot of questions.

Cheers!!

But if you haven't , make sure you do this exercise. There are plenty of step by step guides to ALE IDocs available on the internet . Make sure you read one understand it all the way . Sending IDoc from client 800 to say client 810 on the same server is easy . If possible ,Try an exercise in which you send an IDoc from one system to another system. 


Lets get started . Hope you get some value in these pages :)

Question 1:  What is ALE ?
ALE stands for Application Link Enabling. As it's name indicates , it links two systems.
ALE is a technology that can enable exchange of data between two different Systems ( Sap - Sap OR Sap - Non Sap). ALE technology enables distributed yet integrated installation of SAP systems.
ALE architecture comprises of 3 layers : 

Application layer refers to the application data ( SD , MM , FI or data for any SAP application ) . In this layer the data is collected to be distributed and then sent to the distribution layer.

Distribution layer determines to whom should the data generated by the application layer has to be distributed i.e. it is in the distribution layer that the recipient is determined , the data is formatted or filtered and then an actual is created.

Communication layer takes the responsibility of delivering the Idoc to the receiving system and communicates to the receiving system via tRFC , File ports , FTP or TCP/IP etc.

ALE uses IDoc as a vehicle to transfer data between two systems.


Question 2:  What is EDI ?
EDI stands for Electronic Data Interchange. It refers  to the electronic exchange of business data in a structured format between two systems. The EDI subsystem generally converts the Idoc data into one of the many EDI formats and generates an EDI file in an X12 format. The middleware then translates the X12 file to an IDOC format and the IDOC is sent to the SAP system.


Question 3:  What is an Idoc?   What is IDoc Type?   What is an IDoc Extension ?
An IDoc (Intermediate document) is a vehicle that is used to transfer data from one system to another.
IDoc is not a technology of some sort , but it is just a container that holds data . 
It holds data in a structured format i.e. in the Fields of the Segments.

IDoc Type vs. IDoc: 
An IDoc Type is nothing but a collection of one or more structures defined in a system with specific fields. It does not hold Data.
However, an IDoc is something that holds the values in the fields of the structure defined by IDOC type.

The transaction code to view an IDoc type (Basic and extension) is WE30.
Examples: ORDERS04, DEBMAS04, MATMAS04, CREMAS04.
These are all SAP standard Basic IDoc Types.

You can even have an IDoc extension in which you can use the existing Basic IDoc type and add extra segments and fields to it. Usually we extend an IDoc when the standard SAP IDoc type is not able to cater to the business process.  


Question 4:  What are the types of records in SAP ALE Idocs and where is this information stored ?
There are three types of records in SAP ALE Idocs:
Control Records: Control record information for an IDoc is stored in standard table EDIDC.
Data Records:     Control record information for an IDoc is stored in standard table EDIDD.
Status Records:   Control record information for an IDoc is stored in standard table EDIDS.


Question 5:  What is an Idoc status?  What are the different types of Idoc statuses that you know ?
When an IDoc is sent from one system to another , it goes through variuos stages.The IDoc status indicates the stage that the Idoc in currently in.
There about 75 IDoc statuses.There is no way you can remember those all .
Don't even try to ! You will probably remember only those on which you have worked .

But here are a few that you should know:
0-49 indicates an Outbound IDoc and 50-75 as Inbound IDoc. 

01  IDoc generated
02  Error passing data to port
03  Data passed to port OK

51  Application document not posted
52  Application document not fully posted
53  Application document posted


Question 6:  What is a Port ? What are the types of Ports ?
A port is a communication channel through which Messages can be sent or received in SAP .
The sender and the receiver both specify the port through which they will communicate.

The common port types are the TRFC Port and the File Port.
If both sender and receiver mention TRFC ports, data is exchanged via RFC connections.
If however , a file port is mentioned , the IDOC is written in a flat file at the specified location at the sender system.Then a FTP transfer should be done from that location to the receiver system or a Middleware that will send the file to the receiver system.

The transaction to maintain ports is WE21.


Question 7:  What is a Message type and Idoc Type ? What is the difference between Message type and an IDoc type?
A Message type and an IDoc type are closely related . In fact, you will find that a Message type is always associated with an IDoc type.Whereas an IDoc type is a detailed version with all the segments and fields , a Message type is used just to specify the kind of information that a system can send or receive to or from another system.

So If system SAP1 has a Partner Profile where it specifies MATMAS as an outbound message type , it just means that SAP1 can send material master data to say system SAP2.

If system SAP1 has a Partner Profile where it specifies MATMAS as an inbound message type , it just means that SAP1 can receive material master data from say system SAP2.

What all fields can be sent and received will be specified in the IDoc type.
Some other message types: DEBMAS( Customers), CREMAS(Vendors) belong to the Master data.

The link between a message Type and an IDoc type is maintained in Tcode WE82.


Question 8:  What is a partner profile ? What are the types of partner profiles ?
To be able to communicate with a partner via an IDoc interface, each system needs to maintain a partner profile. A partner profile is a mechanism by which the system can specify what kind of messages (message types) it can send or receive.
Partner profiles can be maintained in WE20.


Question 9:  What is a distribution model in ALE IDocs ? 
The distribution model describes how ALE messages flow between different logical systems.
You can mention the sender and receiver logical systems, the message type to be distributed and also distribute data(IDocs) based on certain conditions by using the distribution model. 
The ALE layer uses the distribution model to control which systems will receive the information(IDocs) and also filter the data based on certain conditions.
Distribution Models can be created and maintained in transaction BD64.


Question 10:  What are process codes ? 


I don't want to make this post too big . So, I will stop here for the time being.

More interview questions on ALE IDocs :

Question 11:How do you read data from an IDoc in a program ?
Question 12:How do you send Idoc from a program ?
Question 13:How do you achieve filtering in a distribution model ?
Question 14:Can I create a flat file from an IDOC ? If Yes , How ?
Question 15:You want to create and send an IDOC to another the moment a PO is created in your            system . How will you achieve this ?
Question 16:How to Reprocess Idocs in SAP?
Question 17:What is a change Pointer?
Question 18:What is serialization of Idocs?
Question 19:Important tcodes in ALE Idocs.
Question 20:Important programs in ALE Idocs:


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