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| -rw-r--r-- | docs/man/nng_compat.3compat.adoc | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/docs/man/nng_compat.3compat.adoc b/docs/man/nng_compat.3compat.adoc index cc6271f4..a0ac64c2 100644 --- a/docs/man/nng_compat.3compat.adoc +++ b/docs/man/nng_compat.3compat.adoc @@ -79,6 +79,51 @@ supplied here later. In the meantime it can be found online at the http://nanomsg.org[nanomsg site]. +There are a few caveats, that should be kept in mind. + +NOTE: Socket numbers can be quite large. +The legacy _libnanomsg_ attempted to reuse socket numbers, like +file descriptors in UNIX systems. +The _nng_ library avoids this to prevent accidental reuse or +collision after a descriptor is closed. +Consequently, socket numbers can become quite large, and should +probably not be used for array indices. + +NOTE: The following options (`nn_getsockopt`) are unsupported: +`NN_PROTOCOL`, `NN_SNDPRIO`, `NN_RCVPRIO`, `NN_IPV4ONLY`. +Some of these will probably be added back in the future when +the relevant support is added to _nng_. + +NOTE: Statistics (`nn_get_statistic`) are unsupported. +The plan is to support statistics in the native _nng_ API, but +we think there is no need for this in a compatibility layer. +Hence, this function returns `ENOTSUP`. + +NOTE: Some transports can support longer URLs than legacy _libnanomsg_ can. +It is a good idea to use short pathnames in URLs if interoperability +is a concern. + +NOTE: Some transports are unusable from this mode. +In particular, this legacy API offers no way to configure +TLS parameters that are required for use. + +NOTE: ABI versioning is not supported. +We don't offer the `NN_VERSION_` macros. Sorry. + +NOTE: Runtime symbol information is not implemented. +Specifically, there is no `nn_symbol()` function yet. +(This may be addressed later if there is a need.) + +IMPORTANT: The `nn_term()` function is destructive and should be avoided. +This function closes down all sockets, and really there is no good +reason to ever use it. +Removal from existing code is advised. +(Keep track of sockets and close them explicitly if necessary.) + +IMPORTANT: It *is* possible at present to intermix sockets between the new and +the old APIs, but this is not a guaranteed feature, and should only +be used temporarily to facilitate transitioning code to the new APIs. + // === Common Functions // // The following common functions exist in _libnng_. |