This documentation is for version v1.3.0 of NNG, but the latest released version is v1.8.0. see the documentation for v1.8.0 for the most up-to-date information.


#include <nng/transport/inproc/inproc.h>

int nng_inproc_register(void);


The inproc transport provides communication support between nng sockets within the same process. This may be used as an alternative to slower transports when data must be moved within the same process.

This transport tries hard to avoid copying data, and thus is very light-weight.


The inproc transport is generally built-in to the nng core, so no extra steps to use it should be necessary.

URI Format

This transport uses URIs using the scheme inproc://, followed by an arbitrary string of text, terminated by a NUL byte.

Multiple URIs can be used within the same application, and they will not interfere with one another.

Two applications may also use the same URI without interfering with each other, and they will be unable to communicate with each other using that URI.

Socket Address

When using an nng_sockaddr structure, the actual structure is of type nng_sockaddr_inproc.

Transport Options

The inproc transport has no special options.

While inproc accepts the option NNG_OPT_RECVMAXSZ for compatibility, the value of the option is ignored with no enforcement. As inproc peers are in the same address space, they are implicitly trusted, and thus it makes no sense to spend cycles protecting a program from itself.