![]() |
|||
![]()
|
![]() |
![]() Click Here! |
![]() |
Transaction Managers Transaction managers (TM) are designed to work within environments in which high availability and guaranteed transaction completion are important. The most common environment for these types of products are banking and financial applications. TM products for most platforms are usually available through the hardware vendors themselves. Examples of these types of products include Encina, Tuxedo, and TOP END. Although TM products could be said to be data base connectivity types of products, some (e.g., Encina) use DCE features. Thus, they can be described as being more complete client/server products than products such as Microsofts ODBC or Borlands IDAPI. Transaction-processing managers are used in heterogeneous distributed client/server environments to support the following:
Enterprise Computing in a New Age (called Encina) is a product based on technologies from the X/Open Consortium and Open Software Foundations DCE. It is a product of Transarc Corp. and provides a highly reliable and easy-to-use transaction-processing environment for open systems and client/server environments. It supports all the core functionality described above using components of DCE with some of its own extensions for multithreading. Encina can start and stop servers dynamically and supports user-defined and abstract data types. Hardware vendors usually remarket this product. Tuxedo, from the former UNIX System Laboratories, requires that application resource managers running under Tuxedo adhere to standard interfaces, namely the X/Open XA interface. The XA interface is a component of the distributed transaction processing (DTP) reference model. XA-compatible interfaces are built into all major UNIX DBMS products. An additional advantage of Tuxedo is that it is independent of underlying network technologies through its use of the UNIX System V Transport Layer Interface (TL1), which supports NetBIOS, Advanced Program-to-Program Communications Logical Unit 6.2 (APPC/LU6.2), Open Systems Interconnection (OSI) protocols, and TCP/IP. Tuxedo is also usually remarketed by the hardware vendors. TOP END from AT&T is also based on X/OPENs DTP environment and uses XA interfaces to UNIX DBMSs. It has direct support for INIX TL1, APPC/LU6.2, and OSI and advanced administration capabilities. It differs from Tuxedo in its support of Kerberos (a crytography-based computer and network security technology) and its ability to dynamic load-leveling. SQL Access Group has merged with X/Opens Data Management Working Group in the new X/Open SQL Access Group. Work is expected to be done on SQL, Stored Procedures,a nd the SQL Call Level Interface. This work should further synthesize standardized messaging protocols. Styles of Client/Server Computing The Gartner Group Mode The Gartner Group model of client of client/server computing is perhaps one of the more widely used. As shown in Exhibit 6-3-10, reading from left to right, the model goes from distributed presentation to distributed data management. Above the network line are the capabilities resident in the server software, and below the network line are the capabilities resident in the client software.
Each variation carries its own impact on application segmentation between the client a nd the server:
|
![]() |
|
Use of this site is subject certain Terms & Conditions. Copyright (c) 1996-1999 EarthWeb, Inc.. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of EarthWeb is prohibited. Please read our privacy policy for details. |