> # About the SequeLink® Components

> SequeLink operates through the following middleware components shown in Figure 1-1:

> - SequeLink Client
> - SequeLink Server
> - SequeLink Manager
> Figure 1-1. SequeLink Components

> ### SequeLink® Client

> SequeLink Client uses a thin-client architecture to provide a single, universal interface for data access that is easy to install and requires "near-zero" administration. SequeLink supports four different clients:

> - SequeLink Client for ODBC supports ODBC applications.
> - SequeLink Client for JDBC supports JDBC applications.
> - SequeLink Client for .NET supports .NET applications.
> - SequeLink Client for ADO supports ADO/OLE DB applications.

> The SequeLink Client is database independent, so, if you decide to incorporate additional data store technologies, you do not need to update or install a new SequeLink Client.

> See "Understanding the SequeLink® Client" for more information about SequeLink Client.

> ### SequeLink® Server

> SequeLink Server installs the following server software service components to provide data connectivity, performance, and administration for two-tier client/server and n-tier Web/application server environments:

> - SequeLink data access services handle data access requests from any SequeLink Client. Multiple SequeLink data access services can run on the same SequeLink Server. For example, SequeLink Server for Oracle and SequeLink Server for Microsoft SQL Server can run side-by-side on the same machine.
> - SequeLink Agent services carry out configuration, management, and monitoring requests from any SequeLink Manager. The SequeLink Agent can service multiple SequeLink services on the same SequeLink Server.

> See "Understanding SequeLink® Services" for more information about SequeLink services.

> ### SequeLink® Server on z/OS

> SequeLink Server installs the following server software service components to provide data connectivity, performance, and administration for two-tier client/server and n-tier Web/application server environments:

> - SequeLink data access services handle data access requests from any SequeLink Client. Each SequeLink Server can host only one SequeLink data access service. Multiple SequeLink Servers can run on the LPAR. For example, SequeLink Server for DB2 v8.1 and DB2 V9.1 can run side-by-side on the same machine.
> - SequeLink Agent services carry out configuration, management, and monitoring requests from any SequeLink Manager. The SequeLink Agent can only service its own SequeLink service within the SequeLink Server.

> ### SequeLink® Manager

> SequeLink Manager is a tool that allows you to centrally configure, manage, and monitor your entire data access infrastructure. By default, this tool is installed on the server that contains the SequeLink Server software; optionally, you can install it on a networked machine.

> The SequeLink Manager is implemented differently depending on the platform.

> See "Understanding the SequeLink® Manager Tool" for more information about the SequeLink Manager.

> ### Understanding the SequeLink® Client

> SequeLink's thin-client component drastically reduces the initial configuration that you must perform and the time you must spend to reconfigure your data access infrastructure when a server configuration changes. Client data sources contain minimal information; most configuration information resides on the server, resulting in "near-zero" client administration.

> Also, SequeLink allows administrators to use Lightweight Directory Access Protocol (LDAP) directories for centralized information retrieval. An ODBC, ADO, or JDBC client data source can reference an LDAP directory to retrieve server connection information, which can reduce the time it takes to reconfigure your infrastructure when a change takes place. For example, if a database must be moved to a different server, the administrator does not have to reconfigure user applications or the client data sources that must now access the new server because the connection information is stored centrally in an LDAP directory. The administrator simply updates the LDAP directory entries to allow the SequeLink Clients to connect to the new server.

> NOTE: The .NET data provider does not support LDAP.