The Server Service

Windows NT also includes a component called the server that resides above TDI. Like the redirector, the server is implemented as a file system driver and directly interacts with various other file system drivers to satisfy input/output (I/O) requests such as reading or writing to a file.

The server processes the connections requested by client-side redirectors, and provides them with access to the resources they request. Like the Workstation service, the Server service is composed of two parts:

Server — A service that runs in the SERVICES.EXE process. Unlike the Workstation service, it is not dependent on the MUP service, because the Server is not a UNC provider. It does not attempt to connect to other computers, but other computers connect to it.

SRV.SYS — A file system driver that handles the interaction with the lower levels and interacts directly with various file system devices to satisfy command requests, such as file read and write.

Processing Remote Requests

When the server service receives a request from a remote computer asking it to read a file that resides on the local hard drive, the following steps occur:

• The low-level network drivers receive the request and pass it to the server driver.

• The server passes a file read request to the appropriate local file system driver.

• The local file system driver calls lower-level disk device drivers to access the file.

• The data is passed back to the local file system driver.

• The local file system driver passes the data back to the server.

• The server passes the data to the lower-level network drivers for transmission back to the client computer.