SQL Server 7.0 is an integral part of the data tier. It is designed to work effectively in a number of application implementation strategies and solutions. By nature, SQL Server exists as a multitier client/server database system. In past implementations of OLTP models, SQL Server would participate in a two-tier client/server environment. The client machine would run an exe-based thick client application that would connect to the SQL Server and conduct business transactions. The thick client application housed the business logic and the code to display output to the user.
In a multitier client/server environment, SQL Server 7.0 assumes a more active role in the OLTP process. By using several new features and technologies, SQL Server 7.0 has the ability to assist in the deployment of a distributed OLTP application and a thin client. In a multitier environment, the business logic is located on a separate server. The thin client is responsible for housing the code to display output to the user and accept input.
Through the use of SQL Server features such as application roles, Windows NT authentication as well as database roles and permissions, SQL Server assists in the deployment of a thin client application across a multitude of platforms, including distributed Internet applications.
Middle tier or business logic tools such as Internet Information Server 4.0/5.0 (IIS) and Microsoft Transaction Server (MTS) fully integrate with SQL Server 7.0. This integration also assists in the creation of a thin client. By keeping the client as thin as possible, developers can adopt OLTP needs to new and emerging technologies. For example, developers for an organization can migrate a client application that communicates with MTS from a Visual Basic rich client to a Visual Studio thin client interface using web forms that communicates with MTS and SQL Server via IIS in an Internet or Intranet distributed environment.