STREAMS Programming Guide

module

A defined set of kernel-level routines and data structures used to process data, status, and control information on a stream. It is an optional element, but there can be many modules in one stream. It consists of a pair of queues (read queue and write queue), and it communicates to other components in a stream by passing messages.

multiplexer

A STREAMS mechanism that enables messages to be routed among multiple streams in the kernel. A multiplexing configuration includes at least one multiplexing pseudo-device driver connected to one or more upper streams and one or more lower streams.

named stream

A stream, typically a pipe, with a name associated with it by way of a call to fattach (that is, a mount operation). This is different from a named pipe (FIFO) in two ways: a named pipe (FIFO) is unidirectional while a named stream is bidirectional; a named stream need not refer to a pipe but can be another type of a stream.

open routine

A procedure in each STREAMS driver and module called by STREAMS on each open system call made on the stream. A module's open procedure is also called when the module is pushed.

packet mode

A feature supported by the STREAMS-based pseudo-terminal subsystem. It is used to inform a process on the master side when state changes occur on the slave side of a pseudo-TTY. It is enabled by pushing a module called pckt on the master side.

persistent link

A connection below a multiplexer that can exist without having an open controlling stream associated with it.

pipe

See STREAMS-based pipe.

pop

A term used when a module that is immediately below the stream head is removed.

pseudo-device driver

A software driver, not directly associated with a physical device, that performs functions internal to a stream such as a multiplexer or log driver.

pseudo-terminal subsystem

A user interface identical to a terminal subsystem except that there is a process in place of a hardware device. It consists of at least a master device, slave device, line-discipline module, and hardware emulation module.

push

A term used when a module is inserted in a stream immediately below the stream head.

pushable module

A module put between the stream head and driver. It performs intermediate transformations on messages flowing between the stream head and driver. A driver is a non-pushable module.

put procedure

A routine in a module or driver associated with a queue that receives messages from the preceding queue. It is the single entry point into a queue from a preceding queue. It may perform processing on the message and will then generally either queue the message for subsequent processing by this queue's service procedure, or will pass the message to the put procedure of the following queue.

queue

A data structure that contains status information, a pointer to routines processing messages, and pointers for administering a stream. It typically contains pointers to a put and service procedure, a message queue, and private data.

read side

A direction of data flow going from a driver towards the stream head. Also called upstream and input side.

read queue

A message queue in a module or driver containing messages moving upstream. Associated with the read system call and input from a driver.

remote mode

A feature available with the pseudo-terminal subsystem. It is used for applications that perform the canonical and echoing functions normally done by the line discipline module and TTY driver. It enables applications on the master side to turn off the canonical processing.

SAD

A STREAMS Administrative Driver that provides an interface to the autopush mechanism.

schedule

To place a queue on the internal list of queues that will subsequently have their service procedure called by the STREAMS scheduler. STREAMS scheduling is independent of the Solaris operating environment process scheduling.

service interface

A set of primitives that define a service at the boundary between a service user and a service provider and the rules (typically represented by a state machine) for allowable sequences of the primitives across the boundary. At a stream/user boundary, the primitives are typically contained in the control part of a message; within a stream, in M_PROTO or M_PCPROTO message blocks.

service procedure

A routine module or driver associated with a queue that receives messages queued for it by the put procedure of that queue. The procedure is called by the STREAMS scheduler. It may perform processing on the message and generally passes the message to the put procedure of the following queue.

service provider

An entity in a service interface that responds to request primitives from the service user with response and event primitives.

service user

An entity in a service interface that generates request primitives for the service provider and consumes response and event primitives.

slave driver

A STREAMS-based device supported by the pseudo-terminal subsystem. It is also called pts and works with a line discipline module and hardware emulation module to provide an interface to a user process.

standard pipe

A mechanism for the unidirectional flow of data between two processes where data written by one process becomes data read by the other process.


	module A defined set of kernel-level routines and data structures used to process data, status, and control information on a stream. It is an optional element, but there can be many modules in one stream. It consists of a pair of queues (read queue and write queue), and it communicates to other components in a stream by passing messages. multiplexer A STREAMS mechanism that enables messages to be routed among multiple streams in the kernel. A multiplexing configuration includes at least one multiplexing pseudo-device driver connected to one or more upper streams and one or more lower streams. named stream A stream, typically a pipe, with a name associated with it by way of a call to `fattach` (that is, a mount operation). This is different from a named pipe (FIFO) in two ways: a named pipe (FIFO) is unidirectional while a named stream is bidirectional; a named stream need not refer to a pipe but can be another type of a stream. open routine A procedure in each STREAMS driver and module called by STREAMS on each `open` system call made on the stream. A module's `open` procedure is also called when the module is pushed. packet mode A feature supported by the STREAMS-based pseudo-terminal subsystem. It is used to inform a process on the master side when state changes occur on the slave side of a pseudo-TTY. It is enabled by pushing a module called `pckt` on the master side. persistent link A connection below a multiplexer that can exist without having an open controlling stream associated with it. pipe See STREAMS-based pipe. pop A term used when a module that is immediately below the stream head is removed. pseudo-device driver A software driver, not directly associated with a physical device, that performs functions internal to a stream such as a multiplexer or log driver. pseudo-terminal subsystem A user interface identical to a terminal subsystem except that there is a process in place of a hardware device. It consists of at least a master device, slave device, line-discipline module, and hardware emulation module. push A term used when a module is inserted in a stream immediately below the stream head. pushable module A module put between the stream head and driver. It performs intermediate transformations on messages flowing between the stream head and driver. A driver is a non-pushable module. put procedure A routine in a module or driver associated with a queue that receives messages from the preceding queue. It is the single entry point into a queue from a preceding queue. It may perform processing on the message and will then generally either queue the message for subsequent processing by this queue's service procedure, or will pass the message to the `put` procedure of the following queue. queue A data structure that contains status information, a pointer to routines processing messages, and pointers for administering a stream. It typically contains pointers to a `put` and `service` procedure, a message queue, and private data. read side A direction of data flow going from a driver towards the stream head. Also called upstream and input side. read queue A message queue in a module or driver containing messages moving upstream. Associated with the `read` system call and input from a driver. remote mode A feature available with the pseudo-terminal subsystem. It is used for applications that perform the canonical and echoing functions normally done by the line discipline module and TTY driver. It enables applications on the master side to turn off the canonical processing. SAD A STREAMS Administrative Driver that provides an interface to the `autopush` mechanism. schedule To place a queue on the internal list of queues that will subsequently have their service procedure called by the STREAMS scheduler. STREAMS scheduling is independent of the Solaris operating environment process scheduling. service interface A set of primitives that define a service at the boundary between a service user and a service provider and the rules (typically represented by a state machine) for allowable sequences of the primitives across the boundary. At a stream/user boundary, the primitives are typically contained in the control part of a message; within a stream, in `M_PROTO` or `M_PCPROTO` message blocks. service procedure A routine module or driver associated with a queue that receives messages queued for it by the `put` procedure of that queue. The procedure is called by the STREAMS scheduler. It may perform processing on the message and generally passes the message to the `put` procedure of the following queue. service provider An entity in a service interface that responds to request primitives from the service user with response and event primitives. service user An entity in a service interface that generates request primitives for the service provider and consumes response and event primitives. slave driver A STREAMS-based device supported by the pseudo-terminal subsystem. It is also called `pts` and works with a line discipline module and hardware emulation module to provide an interface to a user process. standard pipe A mechanism for the unidirectional flow of data between two processes where data written by one process becomes data read by the other process.