Introduction to Networking for NonStop S-Series Servers

Application Programming With Communications
Products
Introduction to Networking for HP NonStop S-Series Servers—520670-005
3-16
Types of File-System Requests
Logical Connection
Data Transfer
Line or Subsystem Control
FILE_OPEN_ Gives the application access to the subsystem process and the
communications line or subdevice and specifies various
requirements of the interaction—for instance, exclusive access
or nowait operation.
FILE_CLOSE_ Terminates the logical connection between an application and
the subsystem process, line, or subdevice. Other applications
can still use the line or subdevice. In some protocols,
FILE_CLOSE_ terminates the physical connection if there are
no remaining users.
WRITE[X] Transfers data or control information from the application to the
subsystem process and, through the process, to the line or
subdevice.
WRITEREAD[X] Transfers data or control information from the application to the
subsystem process and, through the process, to the line or
subdevice or the protocol module controlling the line; receives a
reply.
READ[X] Receives data or other information from the process, line, or
subdevice. READ is intended for use with 16-bit addresses
while READX is intended for use with 32-bit extended
addresses. In some protocols, READ[X] delivers unsolicited
messages from the protocol module to the application. Some
IOPs support a two-step READ[X] that allows the application to
determine the length of the incoming message before
requesting the data, making it unnecessary for the application to
maintain a large, dedicated buffer while waiting for a READ[X] to
be completed.
SETMODE Sets the state or configuration of the line or subdevice or
specifies parameters for interaction between the application and
the subsystem. For example, in some protocols you can use
SETMODE to change the retry count or line speed.
CONTROL Performs actions that alter the state of the line or subdevice, for
example, by hanging up a dial-up line.