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regarding SAP R/3

hiii to all

can any suggest 3tier architecture with real time application (R/3) how exactly it works or what exactly the concept is?

thanks in advance

bhabani

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3 Answers

  • Best Answer
    Posted on Aug 20, 2007 at 04:19 AM

    to simplify everything...

    3 tier means 3 systems (mostly on 3 diff computers)

    1. where you work on -> presentation server

    2. where the commands are executed -> application server

    3. where data is stored -> database server

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  • Posted on Aug 20, 2007 at 05:56 AM

    There 1-tier,2-tier and 3-iter architecture.

    Basically the three tiers are

    1.Presentation Layer(UI).

    2.Application Layer(Programs and Work Process).

    3.Database Layer.(Datas)

    1-tier->All the above three functions are performed by a single Computer.

    2-tier->Presentation and Application Components in One Computer and Database Component in another one.

    3-tier->Presentation in 1 System,Application in another and the Database in another one.

    Hope it helps..

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    Former Member
    Posted on Aug 20, 2007 at 03:44 AM

    Hi,

    Any 3 - tier archintecture works on the following concept:

    Purpose and Origin

    The three tier software architecture (a.k.a. three layer architectures) emerged in the 1990s to overcome the limitations of the two tier architecture (see Two Tier Software Architectures). The third tier (middle tier server) is between the user interface (client) and the data management (server) components. This middle tier provides process management where business logic and rules are executed and can accommodate hundreds of users (as compared to only 100 users with the two tier architecture) by providing functions such as queuing, application execution, and database staging. The three tier architecture is used when an effective distributed client/server design is needed that provides (when compared to the two tier) increased performance, flexibility, maintainability, reusability, and scalability, while hiding the complexity of distributed processing from the user. For detailed information on three tier architectures see Schussel and Eckerson. Schussel provides a graphical history of the evolution of client/server architectures [Schussel 96, Eckerson 95].

    The three tier architecture is used when an effective distributed client/server design is needed that provides (when compared to the two tier) increased performance, flexibility, maintainability, reusability, and scalability, while hiding the complexity of distributed processing from the user. These characteristics have made three layer architectures a popular choice for Internet applications and net-centric information systems.

    Three Tier Software Architectures

    <b>Technical Detail</b>

    A three tier distributed client/server architecture (as shown in Figure 28) includes a user system interface top tier where user services (such as session, text input, dialog, and display management) reside.

    The third tier provides database management functionality and is dedicated to data and file services that can be optimized without using any proprietary database management system languages. The data management component ensures that the data is consistent throughout the distributed environment through the use of features such as data locking, consistency, and replication. It should be noted that connectivity between tiers can be dynamically changed depending upon the user's request for data and services.

    The middle tier provides process management services (such as process development, process enactment, process monitoring, and process resourcing) that are shared by multiple applications.

    The middle tier server (also referred to as the application server) improves performance, flexibility, maintainability, reusability, and scalability by centralizing process logic. Centralized process logic makes administration and change management easier by localizing system functionality so that changes must only be written once and placed on the middle tier server to be available throughout the systems. With other architectural designs, a change to a function (service) would need to be written into every application [Eckerson 95].

    In addition, the middle process management tier controls transactions and asynchronous queuing to ensure reliable completion of transactions [Schussel 96]. The middle tier manages distributed database integrity by the two phase commit process (see Database Two Phase Commit). It provides access to resources based on names instead of locations, and thereby improves scalability and flexibility as system components are added or moved [Edelstein 95].

    Sometimes, the middle tier is divided in two or more unit with different functions, in these cases the architecture is often referred as multi layer. This is the case, for example, of some Internet applications. These applications typically have light clients written in HTML and application servers written in C++ or Java, the gap between these two layers is too big to link them together. Instead, there is an intermediate layer (web server) implemented in a scripting language. This layer receives requests from the Internet clients and generates html using the services provided by the business layer. This additional layer provides further isolation between the application layout and the application logic.

    It should be noted that recently, mainframes have been combined as servers in distributed architectures to provide massive storage and improve security (see Distributed/Collaborative Enterprise Architectures).

    <b>SAP Role in 3 tier Architecture</b>

    [edit] Technology

    SAP R/3 is a client/server based application, utilizing a 3-tiered model. A presentation layer, or client, interfaces with the user. The application layer houses all the business-specific logic, and the database layer records and stores all the information about the system, including transactional and configuration data.

    SAP R/3 functionality is structured using its own proprietary language called ABAP (Advanced Business Application Programming). ABAP, or ABAP/4 is a fourth generation language (4GL), geared towards the creation of simple, yet powerful programs. R/3 also offers a complete development environment where developers can either modify existing SAP code to modify existing functionality or develop their own functions, whether reports or complete transactional systems within the SAP framework.

    ABAP's main interaction with the database system is via Open SQL statements. These statements allow a developer to query, update, or delete information from the database. Advanced topics include GUI development and advanced integration with other systems. With the introduction of ABAP Objects, ABAP provides the opportunity to develop applications with object-oriented programming.

    The most difficult part of SAP R/3 is its implementation. Simply because SAP R/3 is never used the same way in any two places. For instance, Atlas Copco can have a different implementation of SAP R/3 from Procter & Gamble and so forth. Two primary issues are the root of the complexity and of the differences:

    Customization configuration - Within R/3, there are tens of thousands of database tables that may be used to control how the application behaves. For instance, each company will have its own accounting "Chart of Accounts" which reflects how its transactions flow together to represent its activity. That will be specific to a given company. In general, the behavior (and appearance) of virtually every screen and transaction is controlled by configuration tables. This gives the implementor great power to make the application behave differently for different environments. With that power comes considerable complexity.

    Extensions, Bolt-Ons - In any company, there will be a need to develop interface programs to communicate with other corporate information systems. This generally involves developing ABAP/4 code, and considerable "systems integration" effort to either determine what data is to be drawn out of R/3 or to interface into R/3 to load data into the system.

    Due to the complexity of implementation, these companies recruit highly skilled SAP consultants to do the job. The implementation must consider the company's needs and resources. Some companies implement only a few modules of SAP while others may want numerous modules.

    SAP has several layers. The Basis System (BC) includes the ABAP programming language, and is the heart (i.e. the base) of operations and should not be visible to higher level or managerial users. Other customizing and implementation tools exist also. The heart of the system (from a manager's viewpoint) are the application modules.

    Look at the following links:

    https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/90a744a3-55d9-2910-96b9-8a1513fefb1f

    http://en.wikipedia.org/wiki/SAP_R/3>

    Thanks,

    Samantak.

    <b>Rewards points for useful answers.</b>

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    • Former Member Former Member

      Hi,

      The word REAL TIME signifies that the software operates on the instant data environment and can perform all operations on the time of action. There are however 2 operations - 1) real Time 2) Batch Communication

      So Real time handles data in online mode.

      Thanks,

      Samantak.

      <b>Rewards points for useful answers.</b>