SQL Anywhere can appear as an Open Server to client applications. This feature enables Sybase Open Client applications to connect natively to SQL Anywhere databases.

If you simply want to use a Sybase application with SQL Anywhere, you do not need to know any details of Open Client, Open Server, or TDS. However, an understanding of how these components fit together may be helpful for configuring your database and setting up applications. This section explains how the components fit together, but avoids any discussion of the internal features of the components.

Open Clients and Open Servers

SQL Anywhere and other members of the Adaptive Server family act as Open Servers. This means you can develop client applications using the Open Client libraries available from Sybase. Open Client includes both the Client Library (CT-Library) and the older DB-Library interfaces.

For information about developing Open Client applications for use with SQL Anywhere, see Sybase Open Client API.

Tabular Data Stream

Open Clients and Open Servers exchange information using an application protocol called the tabular data stream (TDS). All applications built using the Sybase Open Client libraries are also TDS applications because the Open Client libraries handle the TDS interface. However, some applications (such as jConnect) are TDS applications even though they do not use the Sybase Open Client libraries—they communicate directly using the TDS protocol.

While many Open Servers use the Sybase Open Server libraries to handle the interface to TDS, some applications have a direct interface to TDS of their own. Sybase Adaptive Server Enterprise and SQL Anywhere both have internal TDS interfaces. They appear to client applications as an Open Server, but do not use the Sybase Open Server libraries.

Programming interfaces and application protocols

SQL Anywhere supports two application protocols. Open Client applications and other Sybase applications such as Replication Server and OmniConnect use TDS. ODBC and embedded SQL applications use a separate application protocol specific to SQL Anywhere.

TDS uses TCP/IP

Application protocols such as TDS sit on top of lower-level communications protocols that handle network traffic. SQL Anywhere supports TDS only over the TCP/IP network protocol. In contrast, the SQL Anywhere-specific application protocol supports several network protocols, as well as a shared memory protocol designed for same-computer communication.