SQL Server Engine is comprised of four main components illustrated in the below figure
The Protocol Layer
When the SQL Server Database Engine communicates with an application, it formats the communication in a Microsoft communication format called a Tabular Data Stream (TDS) packet. The network SQL Server Network Interface (SNI) protocol layer, which replaces the Net-Libraries for SQL Server 2000 and Microsoft Data Access Components (MDAC), encapsulates the TDS packet inside a standard communication protocol, such as TCP/IP or named pipes. The SNI protocol layer is common to both the Database Engine and SQL Native Client. The SNI protocol layer is not directly configured. Instead, the server and SQL Native Client are configured to use a network protocol. Then, the Database Engine and SQL Native Client automatically use the appropriate protocol settings. The server creates a SQL Server object called a TDS endpoint for each network protocol. On the server, the TDS endpoints are installed by SQL Server during SQL Server installation.
SQL Server can be configured to support multiple protocols simultaneously, coming from
different clients. Each client connects to SQL Server with a single protocol. If the client
program does not know which protocols SQL Server is listening on, you can configure
the client to attempt multiple protocols sequentially. The following protocols are
available:
Shared Memory The simplest protocol to use, with no configurable settings. Clients using the Shared Memory protocol can connect only to a SQL Server instance running
on the same computer, so this protocol is not useful for most database activity.
Use this protocol for troubleshooting when you suspect that the other protocols
are configured incorrectly. Clients using MDAC 2.8 or earlier cannot use the Shared
Memory protocol. If such a connection is attempted, the client is switched to the
Named Pipes protocol.
Named Pipes A protocol developed for local area networks (LANs). A portion of memory is used by one process to pass information to another process, so that the output of one
is the input of the other. The second process can be local (on the same computer as the
first) or remote (on a networked computer).
TCP/IP The most widely used protocol over the Internet. TCP/IP can communicate across
interconnected networks of computers with diverse hardware architectures and operating
systems. It includes standards for routing network traffic and offers advanced security
features. Enabling SQL Server to use TCP/IP requires the most configuration effort, but
most networked computers are already properly configured.
Virtual Interface Adapter (VIA) A protocol that works with VIA hardware. This is a specialized protocol; configuration details are available from your hardware vendor.
TDS Endpoints
A TDS endpoint is the SQL Server object that represents the communication point between SQL Server and a client. SQL Server automatically creates an endpoint for each of the four protocols supported by SQL Server. By default, all users have access to them when the protocols are enabled. If a network protocol is not enabled, the endpoint still exists, but cannot be used. An additional endpoint is created for the dedicated administrator connection (DAC), which can only be used by members of the sysadmin fixed server role.
The table below summarizes the TDS Endpoints and their attributes
| Purpose | Endpoint name | Configurable | Notes |
| Shared memory | TSQL LocalMachine | No | One endpoint per SQL Server instance. System TDS Endpoint and cannot be deleted |
| Named pipes | TSQL Named Pipes | No | One endpoint per SQL Server instance. System TDS Endpoint and cannot be deleted |
| TCP/IP | TSQL Default TCP | Yes | Can be more than one TCP/IP endpoint per instance |
| VIA | TSQL Default VIA | Yes | |
| DAC | Dedicated Admin Connection | No | One per instance |
| HTTP | HyperText Transport Protocol | Yes | Created by users |
To be continued.
Sami…
No comments:
Post a Comment