SAP ALE （Application Link and Enabling）介紹

ALE 是Application Link and Enabling的縮寫，是SAP專門為SAP與SAP之間所設計的整合中介軟體。IDocs是中介文字 (Intermediate DOCument) 的縮寫，是SAP提供的系統整合專用的資料/訊息格式。ALE在SAP 3.0版本開始就作為SAP整個應用體系的一部分，為分散式資料交換提供了可靠安全的通訊機制。ALE的設計，原本作為兩個SAP流程之間的一種訊息傳遞服務(Messaging Service) ，使SAP與SAP的業務流程之間企業資料能夠有效的交換，為兩個獨立的SAP之間提供了的系統整合服務。不過，隨著應用的發展，ALE/IDocs介面機制也已然成為與其它非SAP系統的標準的整合方式。　　ALE的設計結構可以分為三層，即應用層，資料/訊息分配層和通訊層。　　通訊層是SAP整合機制的基礎，它利用遠端功能呼叫RFC(Remote Function Call) 呼叫SAP系統的功能模組。　　資料/訊息分配層，主要提供三個關鍵服務：　　
1）按資料分配模型決定資料接收者。　　
2）訊息的過濾和轉換。　　
3）資料/訊息的壓縮，以提高傳遞效率。　　

應用層直接與SAP系統介面，生成或從其它系統接收含有路由資訊的訊息文字IDocs，包括訊息接收者的姓名，要求傳送的型別以及對訊息進行處理的規則。

[@more@]The ALE concept always relates to an enterprise structure with areas that have central tasks
and areas with tasks that are decentralized.

 It may be practical for organizations to use separate application systems so that application components can be installed and operated on decentralized systems that are technically independent of each other.
 The ALE concept supports the implementation and operation of distributed SAP applications. It is based on business-controlled messaging with consistent data storage on loosely coupled systems. The applications are integrated through the message exchange, not via a central database.
 To implement a distributed, yet integrated system, the customer must specify in a logical model, which applications are to run on which systems and how the applications are to exchange data with each other.
 On the technical side, the data exchange is carried out via IDocs (intermediate documents) as used in the EDI (Electronic Data Interchange) interface. On the application side, EDI supports information exchange between R/3 systems in different enterprises, whereas ALE supports information exchange within one enterprise. The ALE distribution mechanism is similar to the EDI mechanism. In ALE, business processes are distributed at the transaction level.

 The procurement of materials via the plant in a company code can be handled in a local system. However, payments to vendors and the general ledger are managed in a central system.
 In order that both organizations use the same master data, the head office distributes the master data to the local system. Thus the transaction data in the local systems for which IDocs exist can be sent to the head office without inconsistencies.
 Examples of data that can be distributed:
­ Master data: Customers, vendors, G/L accounts, cost centers, cost elements, activity types
­ Transaction data: Incoming invoices, outgoing invoices, Financial Accounting line items, Controlling documents
 The SAP standard system is delivered with some ALE scenarios. For example:
­ Central contract management in Purchasing
­ Distributed Inventory Management
­ Central Materials Management master data
 The message types required for the distribution via IDocs are also delivered by SAP. You can also define your own ALE scenarios.
 Business to Business Procurement works through ALE with an R/3 backend system