---
name: "zmq_inproc"
section: "7"
platform: "linux"
package: "zeromq"
version: "4.3.5-3"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/zmq_inproc"
---

# zmq\_inproc(7)

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

## NAME

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

## 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)](/zmq_init/3.md) for details.

## 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

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

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

**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

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

## 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**.