ZMQ\_INPROC(7) 0MQ Manual ZMQ\_INPROC(7)

# [NAME](#NAME)

zmq\_inproc - 0MQ local in-process (inter-thread) communication transport

# [SYNOPSIS](#SYNOPSIS)

The in-process transport passes messages via memory directly between threads sharing a single 0MQ *context*.

**Note**

No I/O threads are involved in passing messages using the *inproc* transport. Therefore, if you are using a 0MQ *context* for in-process messaging only you can initialise the *context* with zero I/O threads. See [**zmq\_init**(3)](/man/os/zeromq/zmq_init.3) for details.

# [ADDRESSING](#ADDRESSING)

A 0MQ endpoint is a string consisting of a *transport*:// followed by an *address*. The *transport* specifies the underlying protocol to use. The *address* specifies the transport-specific address to connect to.

For the in-process transport, the transport is inproc, and the meaning of the *address* part is defined below.

## [Assigning a local address to a socket](#Assigning_a_local_address_to_a_socket)

When assigning a local address to a *socket* using *zmq\_bind()* with the *inproc* transport, the *endpoint* shall be interpreted as an arbitrary string identifying the *name* to create. The *name* must be unique within the 0MQ *context* associated with the *socket* and may be up to 256 characters in length. No other restrictions are placed on the format of the *name*.

## [Connecting a socket](#Connecting_a_socket)

When connecting a *socket* to a peer address using *zmq\_connect()* with the *inproc* transport, the *endpoint* shall be interpreted as an arbitrary string identifying the *name* to connect to. Before version 4.0 he *name* must have been previously created by assigning it to at least one *socket* within the same 0MQ *context* as the *socket* being connected. Since version 4.0 the order of *zmq\_bind()* and *zmq\_connect()* does not matter just like for the tcp transport type.

# [EXAMPLES](#EXAMPLES)

**Assigning a local address to a socket**.

```
//  Assign the in-process name "#1"
rc = zmq_bind(socket, "inproc://#1");
assert (rc == 0);
//  Assign the in-process name "my-endpoint"
rc = zmq_bind(socket, "inproc://my-endpoint");
assert (rc == 0);
```

**Connecting a socket**.

```
//  Connect to the in-process name "#1"
rc = zmq_connect(socket, "inproc://#1");
assert (rc == 0);
//  Connect to the in-process name "my-endpoint"
rc = zmq_connect(socket, "inproc://my-endpoint");
assert (rc == 0);
```

# [SEE ALSO](#SEE_ALSO)

[**zmq\_bind**(3)](/man/os/zeromq/zmq_bind.3) [**zmq\_connect**(3)](/man/os/zeromq/zmq_connect.3) [**zmq\_ipc**(7)](/man/os/zeromq/zmq_ipc.7) [**zmq\_tcp**(7)](/man/os/zeromq/zmq_tcp.7) [**zmq\_pgm**(7)](/man/os/zeromq/zmq_pgm.7) [**zmq\_vmci**(7)](/man/os/zeromq/zmq_vmci.7) [**zmq**(7)](/man/os/zeromq/zmq.7)

# [AUTHORS](#AUTHORS)

This page was written by the 0MQ community. To make a change please read the 0MQ Contribution Policy at **http://www.zeromq.org/docs:contributing**.

10/24/2026 0MQ 4.3.5

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Document: zmq_inproc(7) from zeromq 4.3.5-r14 (Chainguard OS)
Source: https://github.com/zeromq/libzmq