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Migrating from NNG 1.x

There are some incompatibities from NNG 1.x. This guide should help in migrating applications to use NNG 2.0.

Nanomsg Compatibility

Applications using the legacy libnanomsg API will have to be updated to native NNG interfaces. See the Migrating From libnanomsg chapter for details.

Library Initialization

It is now required for applications to initialize the library explicitly before using it. This is done using the [nng_init] function.

Transport Specific Functions

Transports have not needed to be registered for a long time now, and the functions for doing so have been removed. These functions can be simply removed from your application:

  • nng_inproc_register
  • nng_ipc_register
  • nng_tls_register
  • nng_tcp_register
  • nng_ws_register
  • nng_wss_register
  • nng_zt_register

Additionally, the header files containing these functions have been removed, such as nng/transport/ipc/ipc.h. Simply remove #include references to those files.

(Special exception: The options for ZeroTier are still located in the nng/transport/zerotier/zerotier.h.)

The NNG_OPT_WSS_REQUEST_HEADERS and NNG_OPT_WSS_RESPONSE_HEADERS aliases for NNG_OPT_WS_OPT_WS_REQUEST_HEADERS and NNG_OPT_WS_RESPONSE_HEADERS have been removed. Just convert any use of them to NNG_OPT_WS_REQUEST_HEADERS or NNG_OPT_WS_RESPONSE_HEADERS as appropriate.

TLS Configuration

The support for configuring TLS via NNG_OPT_TLS_CONFIG, NNG_TLS_AUTH_MODE, NNG_OPT_TLS_CA_FILE, NNG_OPT_TLS_SERVER_NAME, and similar has been removed.

Instead configuration must be performed by allocating a nng_tls_config object, and then setting fields on it using the appropriate functions, after which it may be configured on a listener or dialer using the [nng_listener_set_tls] or [nng_dialer_set_tls] functions.

Likewise, when using the streams API, use the [nng_stream_listener_set_tls] or [nng_stream_dialer_set_tls] functions.

Note that the declarations needed for TLS configuration are now available in <nng/nng.h>, rather than the supplemental header.

Old TLS Versions Removed

Support for very old TLS versions 1.0 and 1.1 is removed. Further, the NNG_TLS_1_0 and NNG_TLS_1_1 constants are also removed. Applications should use NNG_TLS_1_2 or even NNG_TLS_1_3 instead.

Support for Local Addresses in Dial URLs Removed

NNG 1.x had an undocumented ability to specify the local address to bind to when dialing, by using the local address in front of the destination address separated by a semicolon. This was provided for legacy libnanomsg compatilibility, and is no longer offered. The correct way to specify a local address is by setting NNG_OPT_LOCADDR on the dialer.

Option Functions

The previously deprecated nng_pipe_getopt_xxx family of functions is removed. Applications should use nng_pipe_get and related functions instead.

The socket option function families for nng_getopt and nng_setopt have been removed as well. In this case, use the nng_socket_get and nng_socket_set functions as appropriate.

The _getopt and _setopt functions for contexts, listeners, and dialers are no longer present. Simply changing _getopt to _get or _setopt to _set in the function name should be sufficient in most cases.

Untyped Option Functions Removed

The following functions are removed. To access options, use a proper typed access function, such as one ending in a suffix like _bool (to access a bool typed option).

  • nng_ctx_get
  • nng_ctx_set
  • nng_dialer_get
  • nng_dialer_set
  • nng_listener_get
  • nng_listener_set
  • nng_pipe_get
  • nng_socket_get
  • nng_socket_set
  • nng_stream_get
  • nng_stream_set
  • nng_stream_dialer_get
  • nng_stream_dialer_set
  • nng_stream_listener_get
  • nng_stream_listener_set

Stream Options

The ability to set options on streams after they have been created is no longer present. (It turns out that this was not very useful.) All functions nng_stream_set_xxx are removed. For tuning the NNG_OPT_TCP_NODELAY or similar properties, set the option on the listener or dialer that creates the stream instead.

Transport Options

A number of transport options can no longer be set on the socket. Instead these options must be set on the endpoint (dialer or listener) using the appropriate nng_dialer_set or nng_listener_set option. This likely means that it is necessary to allocate and configure the endpoint before attaching it to the socket. This will also afford a much more fine-grained level of control over transport options.

The following options are copied from the socket when creating a dialer or listener, but afterwards will not be changed on the dialer or listener if the socket changes. It is recommended to set them properly on the socket before creating dialers or listeners, or set them explicitly on the dialer or listener directly:

  • NNG_OPT_RECONNMINT
  • NNG_OPT_RECONNMAXT
  • NNG_OPT_RECVMAXSZ

The latter option is a hint for transports and intended to facilitate early detection (and possibly avoidance of extra allocations) of oversize messages, before bringing them into the socket itself.

Socket Options

The NNG_OPT_PROTO, NNG_OPT_PROTONAME, NNG_OPT_PEER, and NNG_OPT_PEERNAME options have been replaced by functions instead of options. Use [nng_socket_proto_id], [nng_socket_peer_id], [nng_socket_proto_name], and [nng_socket_peer_name] instead. Note that the new functions provide a reference to a static string, and thus do not require allocation, and the returned strings should not be freed. Also the IDs are provided as uint16_t, matching the actual wire protocol values, instead of int.

The NNG_OPT_RAW option has aso been replaced by a function, [nng_socket_raw].

The NNG_OPT_SENDFD and NNG_OPT_RECVFD options have been replaced by [nng_socket_get_send_poll_fd] and [nng_socket_get_recv_poll_fd] respectively.

The NNG_OPT_SOCKNAME function is removed. This was provided for application use, and never used internally by NNG. Applications should keep track of this information separately.

Subscriptions

The NNG_OPT_SUB_SUBSCRIBE and NNG_OPT_SUB_UNSUBCRIBE options have been replaced by the following functions: [nng_sub0_socket_subscribe], [nng_sub0_socket_unsubscribe], [nng_sub0_ctx_subscribe] and [nng_sub0_ctx_unsubscribe]. These functions, like the options they replace, are only applicable to SUB sockets.

Statistics Use Constified Pointers

A number of the [statistics][statistic] functions take, or return, const nng_stat * instead of plain nng_stat *. The ABI has not changed, but it may be necessary to declare certain methods variables const to avoid warnings about misuse of const.

Wildcards Not Valid in URLs

The use of * to act as a wild card meaning all local interface addresses is removed. The empty string already performs this function, and unlike * is RFC compliant.

URL Structure Members

The details of [nng_url] have changed as follows:

  • u_port is no longer a string, but a uint16_t
  • u_scheme is a const char *
  • u_requri is removed - it can be easily formulated from the other fields.
  • u_host is removed - use u_hostname and u_port to construct if needed
  • u_rawurl is removed - a "cooked" URL can be obtained from the new [nng_url_sprintf] function.

{{#include ../xref.md}}