Microsoft Corporation
October 1999
Summary: Describes middle-tier data caching with COM/MTS and COM+ and provides resources for further information. (2 printed pages)
In some scenarios, data-intensive Web-oriented applications can benefit from middle-tier caching (that is, caching data at locations separate from the central database where that information is stored and transactional operations are performed). This article provides information and resources for Microsoft technologies that can be used for middle-tier caching with data accessed from a Microsoft® COM+ or COM/MTS component.
The main goal of caching on the middle tier is to make data readily available to applications without repeated involvement from central database servers to provide the data. Middle-tier caching is most beneficial when the majority of data access operations are read-oriented. There is no reason to cache data on the middle tier if the data changes with each user transaction. Lookup lists for items that change only infrequently, such as product catalogs, benefit most from middle-tier data caching.
Developers who need to cache data that will be used by COM/MTS or COM+ objects should consider using Microsoft SQL Server™ as a middle-tier caching server. SQL Server functions as a highly scalable online transaction processing (OLTP) database server, designed to meet the needs of enterprise-level centralized database servers. However, SQL Server functions equally well as an easy-to-manage middle-tier caching server. Developers who need to cache data from a centralized SQL Server database should consider moving data from the central database server to middle-tier data caching servers with SQL Server replication. SQL Server Data Transformation Services make it possible to put data from any data source supported by Microsoft OLE DB or Open Database Connectivity (ODBC) into SQL Server. For more information on developing for SQL Server, please see the following articles:
Improving MDAC Application Performance (includes SQL Server sample code).
ADO and SQL Server Developer’s Guide (includes SQL Server sample code).
ADO Tutorial (includes SQL Server sample code).
Designing Efficient Applications for Microsoft SQL Server.
Rowset Persistence in MDAC (includes SQL Server sample code).
Developers may consider using ADO Disconnected Recordsets to store data on a Web server or application server for local access. For more information and sample code, see http://support.microsoft.com/support/kb/articles/q190/7/17.asp.
A significant amount of ADO and SQL Server sample code that illustrates data-tier design can be found as part of the Duwamish Books sample in the MSDN Library.