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100 lines
3.7 KiB
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100 lines
3.7 KiB
Plaintext
= zmq_ipc(7)
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== NAME
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zmq_ipc - 0MQ local inter-process communication transport
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== SYNOPSIS
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The inter-process transport passes messages between local processes using a
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system-dependent IPC mechanism.
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NOTE: The inter-process transport is currently only implemented on operating
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systems that provide UNIX domain sockets.
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== ADDRESSING
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A 0MQ endpoint is a string consisting of a 'transport'`://` followed by an
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'address'. The 'transport' specifies the underlying protocol to use. The
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'address' specifies the transport-specific address to connect to.
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For the inter-process transport, the transport is `ipc`, and the meaning of
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the 'address' part is defined below.
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Binding a socket
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~~~~~~~~~~~~~~~~
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When binding a 'socket' to a local address using _zmq_bind()_ with the 'ipc'
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transport, the 'endpoint' shall be interpreted as an arbitrary string
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identifying the 'pathname' to create. The 'pathname' must be unique within the
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operating system namespace used by the 'ipc' implementation, and must fulfill
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any restrictions placed by the operating system on the format and length of a
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'pathname'.
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When the address is wild-card `*`, _zmq_bind()_ shall generate a unique temporary
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pathname. The caller should retrieve this pathname using the ZMQ_LAST_ENDPOINT
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socket option. See xref:zmq_getsockopt.adoc[zmq_getsockopt] for details.
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NOTE: any existing binding to the same endpoint shall be overridden. That is,
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if a second process binds to an endpoint already bound by a process, this
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will succeed and the first process will lose its binding. In this behaviour,
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the 'ipc' transport is not consistent with the 'tcp' or 'inproc' transports.
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NOTE: the endpoint pathname must be writable by the process. When the endpoint
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starts with '/', e.g., `ipc:///pathname`, this will be an _absolute_ pathname.
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If the endpoint specifies a directory that does not exist, the bind shall fail.
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NOTE: on Linux only, when the endpoint pathname starts with `@`, the abstract
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namespace shall be used. The abstract namespace is independent of the
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filesystem and if a process attempts to bind an endpoint already bound by a
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process, it will fail. See unix(7) for details.
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NOTE: IPC pathnames have a maximum size that depends on the operating system.
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On Linux, the maximum is 113 characters including the "ipc://" prefix (107
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characters for the real path name).
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Unbinding wild-card address from a socket
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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When wild-card `*` 'endpoint' was used in _zmq_bind()_, the caller should use
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real 'endpoint' obtained from the ZMQ_LAST_ENDPOINT socket option to unbind
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this 'endpoint' from a socket using _zmq_unbind()_.
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Connecting a socket
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~~~~~~~~~~~~~~~~~~~
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When connecting a 'socket' to a peer address using _zmq_connect()_ with the
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'ipc' transport, the 'endpoint' shall be interpreted as an arbitrary string
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identifying the 'pathname' to connect to. The 'pathname' must have been
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previously created within the operating system namespace by assigning it to a
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'socket' with _zmq_bind()_.
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== EXAMPLES
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.Assigning a local address to a socket
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----
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// Assign the pathname "/tmp/feeds/0"
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rc = zmq_bind(socket, "ipc:///tmp/feeds/0");
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assert (rc == 0);
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----
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.Connecting a socket
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----
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// Connect to the pathname "/tmp/feeds/0"
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rc = zmq_connect(socket, "ipc:///tmp/feeds/0");
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assert (rc == 0);
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----
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== SEE ALSO
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* xref:zmq_bind.adoc[zmq_bind]
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* xref:zmq_connect.adoc[zmq_connect]
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* xref:zmq_inproc.adoc[zmq_inproc]
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* xref:zmq_tcp.adoc[zmq_tcp]
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* xref:zmq_pgm.adoc[zmq_pgm]
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* xref:zmq_vmci.adoc[zmq_vmci]
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* xref:zmq_getsockopt.adoc[zmq_getsockopt]
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* xref:zmq.adoc[zmq]
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== AUTHORS
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This page was written by the 0MQ community. To make a change please
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read the 0MQ Contribution Policy at <https://zeromq.org/how-to-contribute/>.
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