In this document you will learn the step-by-step procedure to setup the ALE system and go through a transaction between to clients.  View/Download ALE Part 1 and ALE Part 2 (Taken from SAPPoint.com).

To understand more about ALE Programming you may also need the ALE QUick Start Guide and the ALE Programming Guide.

To develop and configure a new custom ALE scenario, comprises 5 steps:
1. Design and develop the custom IDoc with it’ s segments and a new message type
2. Configure the ALE environment with the new IDoc and message type (customer model,
partner profiles and linking IDoc to message type)
3. Develop the outbound process which does the following:

1. Populates the custom IDoc with control info and functional data
2. Sends the IDoc to the ALE layer for distribution
3. Updates status and handles errors

4. Configure the ALE inbound side (partner profiles with inbound process code)
5. Develop the inbound process which does the following:

1. Reads the IDoc into a BDC table; selects other data that is required
2. Runs transaction using call transaction or BDC session
3. Updates status and handles errors

View/Download the Complete Guide on ALE Configuration and Development.

Beginners guide on IDOC and ALE to teach you about:

IDOC

What Is IDOC.
What are the main advantages of IDOC?
Difference Between EDI and IDOC.
Delete/Remove of IDocs from R3.
IDOC Components & Structures.

ALE

ALE - Introduction
Data Distribution Model
ALE Process
ALE Functionality
ALE Converters

One of the readers send me these documents which are available on the esnips folder. Just visit the below link.

http://www.esnips.com/web/sivaabap

Contains the study material on ABAP and Cross Applications.

Few learning docs on ALE and EDI Technologies from sappoint.

• Understanding and Optimizing Your ALE Data Distribution Controlling ALE Processing
• Application Link Enabling - 1
• Application Link Enabling - II

Download the most famous ebook on Cross Applications.

ALE EDI & IDOC Technologies for SAP - 2nd Edition for free.