nng_send*mdbook

9 files changed, 256 insertions, 269 deletions

diff --git a/docs/reference/src/sock/nng_recv.md b/docs/reference/src/sock/nng_recv.md
index 178661f7..f594cafc 100644
--- a/docs/reference/src/sock/nng_recv.md
+++ b/docs/reference/src/sock/nng_recv.md
@@ -46,11 +46,8 @@ updated with the actual message body length copied into _data_.
 > [!NOTE]
 > The semantics of what receiving a message means vary from protocol to
 > protocol, so examination of the protocol documentation is encouraged.
-> (For example, with a [_REQ_][req] socket a message may only be received
-> after a request has been sent, and a [_SUB_][sub] socket
-> may only receive messages corresponding to topics to which it has subscribed.)
-> Furthermore, some protocols may not support receiving data at all, such as
-> [_PUB_][pub].
+> Furthermore, some protocols may not support receiving data at all, or
+> may require other conditions be met before they can receive.
 
 > [!TIP]
 > The `NNG_FLAG_ALLOC` flag can be used to reduce data copies, thereby
diff --git a/docs/reference/src/sock/nng_recv_aio.md b/docs/reference/src/sock/nng_recv_aio.md
index 257ec691..8baeb2a4 100644
--- a/docs/reference/src/sock/nng_recv_aio.md
+++ b/docs/reference/src/sock/nng_recv_aio.md
@@ -38,12 +38,8 @@ but `nng_aio_result()` will be non-zero.
 > [!NOTE]
 > The semantics of what receiving a message means varies from protocol to
 > protocol, so examination of the protocol documentation is encouraged.
-> For example, with [_PUB_][pub] socket the data is broadcast, so that
-> only peers who have a suitable subscription will be able to receive it.
-> Furthermore, some protocols may not support receiving (such as
-> _PUB_) or may require other conditions.
-> (For example, [_REQ_][req] sockets cannot normally receive data
-> until they have first sent a request.)
+> Furthermore, some protocols may not support receiving
+> or may require other conditions be met before receiving messages.
 
 ## ERRORS
 
diff --git a/docs/reference/src/sock/nng_recvmsg.md b/docs/reference/src/sock/nng_recvmsg.md
index 3d3912c0..9e081893 100644
--- a/docs/reference/src/sock/nng_recvmsg.md
+++ b/docs/reference/src/sock/nng_recvmsg.md
@@ -39,9 +39,8 @@ disposing of it when it is no longer needed.
 > [!NOTE]
 > The semantics of what receiving a message means vary from protocol to
 > protocol, so examination of the protocol documentation is encouraged.
-> (For example, with a [_REQ_][req] socket a message may only be received
-> after a request has been sent).
-> Furthermore, some protocols do not support receiving data at all.
+> Furthermore, some protocols do not support receiving data at all, or
+> may require other conditions be met before receiving messages.
 
 ## RETURN VALUES
 
diff --git a/docs/reference/src/sock/nng_send.3.adoc b/docs/reference/src/sock/nng_send.3.adoc
deleted file mode 100644
index 4932712a..00000000
--- a/docs/reference/src/sock/nng_send.3.adoc
+++ /dev/null
@@ -1,90 +0,0 @@
-# nng_send
-
-## NAME
-
-nng_send --- send data
-
-## SYNOPSIS
-
-```
-#include <nng/nng.h>
-
-int nng_send(nng_socket s, void *data, size_t size, int flags);
-```
-
-## DESCRIPTION
-
-The `nng_send()` function sends a message containing the _data_ of
-length _size_ using the xref:nng_socket.5.adoc[socket] _s_.
-
-NOTE: The semantics of what sending a message means vary from protocol to
-protocol, so examination of the protocol documentation is encouraged.
-(For example, with an xref:nng_pub.7.adoc[_pub_] socket the data is broadcast, so that
-any peers who have a suitable subscription will be able to receive it using
-xref:nng_recv.3.adoc[`nng_recv()`] or a similar function.)
-Furthermore, some protocols may not support sending data (such as
-xref:nng_sub.7.adoc[_sub_]) or may require other conditions.
-(For example, xref:nng_rep.7.adoc[_rep_] sockets cannot normally send data,
-which are responses to requests, until they have first received a request.)
-
-The _flags_ may contain either of (or neither of) the following values:
-
-`NNG_FLAG_NONBLOCK`::
-    The function returns immediately, regardless of whether
-    the socket is able to accept the data or not.  If the socket is unable
-    to accept the data (such as if backpressure exists because the peers
-    are consuming messages too slowly, or no peer is present), then the
-    function will return with `NNG_EAGAIN`.  If this flag is not specified,
-    then the function will block if such a condition exists.
-
-`NNG_FLAG_ALLOC`::
-    The _data_ was allocated using xref:nng_alloc.3.adoc[`nng_alloc()`], or was
-    obtained from a call to xref:nng_recv.3.adoc[`nng_recv()`] with
-    the `NNG_FLAG_ALLOC` flag.
-    If this function returns success, then the _data_ is "owned" by the
-    function, and it will assume responsibility for calling
-    xref:nng_free.3.adoc[`nng_free()`] when it is no longer needed.
-    In the absence of this flag, the _data_ is copied by the implementation
-    before the function returns to the caller.
-
-TIP: The `NNG_FLAG_ALLOC` flag can be used to reduce data copies, thereby
-increasing performance.
-
-NOTE: Regardless of the presence or absence of `NNG_FLAG_NONBLOCK`, there may
-be queues between the sender and the receiver.
-Furthermore, there is no guarantee that the message has actually been delivered.
-Finally, with some protocols, the semantic is implicitly `NNG_FLAG_NONBLOCK`,
-such as with xref:nng_pub.7.adoc[_pub_] sockets, which are best-effort delivery only.
-
-IMPORTANT: When using `NNG_FLAG_ALLOC`, it is important that the value of _size_
-match the actual allocated size of the data.
-Using an incorrect size results
-in unspecified behavior, which may include heap corruption, program crashes,
-or trans-dimensional mutation of the program's author.
-
-## RETURN VALUES
-
-This function returns 0 on success, and non-zero otherwise.
-
-## ERRORS
-
-* `NNG_EAGAIN`: The operation would block, but `NNG_FLAG_NONBLOCK` was specified.
-* `NNG_ECLOSED`: The socket _s_ is not open.
-* `NNG_EINVAL`: An invalid set of _flags_ was specified.
-* `NNG_EMSGSIZE`: The value of _size_ is too large.
-* `NNG_ENOMEM`: Insufficient memory is available.
-* `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
-* `NNG_ESTATE`: The socket _s_ cannot send data in this state.
-* `NNG_ETIMEDOUT`: The operation timed out.
-
-## SEE ALSO
-
-[nng_alloc][nng_alloc],
-[nng_free][nng_free],
-[nng_recv][nng_recv],
-[nng_sendmsg][nng_sendmsg],
-[nng_strerror][nng_strerror],
-[nng_socket][nng_socket],
-[nng][nng]
-
-{{#include ../refs.md}}
diff --git a/docs/reference/src/sock/nng_send.md b/docs/reference/src/sock/nng_send.md
new file mode 100644
index 00000000..c36cedbb
--- /dev/null
+++ b/docs/reference/src/sock/nng_send.md
@@ -0,0 +1,93 @@
+# nng_send
+
+## NAME
+
+nng_send --- send data
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_send(nng_socket s, void *data, size_t size, int flags);
+```
+
+## DESCRIPTION
+
+The `nng_send()` function sends a message containing the _data_ of
+length _size_ using the [socket][socket] _s_.
+
+> [!NOTE]
+> The semantics of what sending a message means vary from protocol to
+> protocol, so examination of the protocol documentation is encouraged.
+> For example, on [_PUB_][pub] sockets the data is broadcast, so that
+> any peers who have a suitable subscription will be able to receive it.
+> Furthermore, some protocols may not support sending data
+> or may require other conditions.
+> For example, [_REP_][rep] sockets cannot normally send data
+> until they have first received a request.)
+
+The _flags_ may contain either of (or neither of) the following values:
+
+- {{i:`NNG_FLAG_NONBLOCK`}}: \
+   The function returns immediately, regardless of whether
+  the socket is able to accept the data or not. If the socket is unable
+  to accept the data (such as if backpressure exists because the peers
+  are consuming messages too slowly, or no peer is present), then the
+  function will return with `NNG_EAGAIN`. If this flag is not specified,
+  then the function will block if such a condition exists.
+
+- {{i:`NNG_FLAG_ALLOC`}}: \
+   The _data_ was allocated using [`nng_alloc()`][nng_alloc], or was
+  obtained from a call to [`nng_recv()`][nng_recv] with
+  the `NNG_FLAG_ALLOC` flag.
+  If this function returns success, then the _data_ is "owned" by the
+  function, and it will assume responsibility for calling
+  [`nng_free()`][nng_free] when it is no longer needed.
+  In the absence of this flag, the _data_ is copied by the implementation
+  before the function returns to the caller.
+
+> [!TIP]
+> The `NNG_FLAG_ALLOC` flag can be used to reduce data copies, thereby
+> increasing performance. However, the [`nng_sendmsg()`][nng_sendmsg] function is even better in this regard, and should be preferred over this
+> function when possible.
+
+> [!NOTE]
+> Regardless of the presence or absence of `NNG_FLAG_NONBLOCK`, there may
+> be queues between the sender and the receiver.
+> Furthermore, there is no guarantee that the message has actually been delivered.
+> Finally, with some protocols, the semantic is implicitly `NNG_FLAG_NONBLOCK`,
+> such as with _PUB_ sockets, which are best-effort delivery only.
+
+> [!IMPORTANT]
+> When using `NNG_FLAG_ALLOC`, it is important that the value of _size_
+> match the actual allocated size of the data.
+> Using an incorrect size results
+> in unspecified behavior, which may include heap corruption, program crashes,
+> or teleportation of the program's author to an alternate universe.
+
+## RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_EAGAIN`: The operation would block, but `NNG_FLAG_NONBLOCK` was specified.
+- `NNG_ECLOSED`: The socket _s_ is not open.
+- `NNG_EINVAL`: An invalid set of _flags_ was specified.
+- `NNG_EMSGSIZE`: The value of _size_ is too large.
+- `NNG_ENOMEM`: Insufficient memory is available.
+- `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
+- `NNG_ESTATE`: The socket _s_ cannot send data in this state.
+- `NNG_ETIMEDOUT`: The operation timed out.
+
+## SEE ALSO
+
+[Sockets][socket],
+[nng_alloc][nng_alloc],
+[nng_free][nng_free],
+[nng_recv][nng_recv],
+[nng_send_aio][nng_send_aio],
+[nng_sendmsg][nng_sendmsg]
+
+{{#include ../refs.md}}
diff --git a/docs/reference/src/sock/nng_send_aio.3.adoc b/docs/reference/src/sock/nng_send_aio.3.adoc
deleted file mode 100644
index 4597619c..00000000
--- a/docs/reference/src/sock/nng_send_aio.3.adoc
+++ /dev/null
@@ -1,81 +0,0 @@
-# nng_send_aio
-
-## NAME
-
-nng_send_aio --- send message asynchronously
-
-## SYNOPSIS
-
-```
-#include <nng/nng.h>
-
-void nng_send_aio(nng_socket s, nng_aio *aio);
-```
-
-## DESCRIPTION
-
-The `nng_send_aio()` sends a xref:nng_msg.5.adoc[message] using the
-xref:nng_socket.5.adoc[socket] _s_ asynchronously.
-
-The message to send must have previously been set on the _aio_
-using the xref:nng_aio_set_msg.3.adoc[`nng_aio_set_msg()`] function.
-The function assumes ownership of the message.
-
-If the message was successfully queued for delivery to the socket,
-then the _aio_ will be completed, and xref:nng_aio_result.3.adoc[`nng_aio_result()`]
-will return zero.  In this case the socket will dispose of the
-message when it is finished with it.
-
-NOTE: The operation will be completed, and the callback associated
-with the _aio_ executed, as soon as the socket accepts the message
-for sending.
-This does _not_ indicate that the message was actually delivered, as it
-may still be buffered in the sending socket, buffered in the receiving
-socket, or in flight over physical media.
-
-If the operation fails for any reason (including cancellation or timeout),
-then the _aio_ callback will be executed and
-xref:nng_aio_result.3.adoc[`nng_aio_result()`]
-will return a non-zero error status.
-In this case, the callback has a responsibility to retrieve the message from
-the _aio_ with
-xref:nng_aio_get_msg.3.adoc[`nng_aio_get_msg()`] and dispose of it appropriately.
-(This may include retrying the send operation on the same or a different
-socket, or deallocating the message with xref:nng_msg_free.3.adoc[`nng_msg_free()`].)
-
-NOTE: The semantics of what sending a message means varies from protocol to
-protocol, so examination of the protocol documentation is encouraged.
-(For example, with a xref:nng_pub.7.adoc[_pub_] socket the data is broadcast, so that
-any peers who have a suitable subscription will be able to receive it using
-xref:nng_recv.3.adoc[`nng_recv()`] or a similar function.)
-Furthermore, some protocols may not support sending (such as
-xref:nng_sub.7.adoc[_sub_]) or may require other conditions.
-(For example, xref:nng_rep.7.adoc[_rep_] sockets cannot normally send data, which
-are responses to requests, until they have first received a request.)
-
-## RETURN VALUES
-
-None.  (The operation completes asynchronously.)
-
-## ERRORS
-
-* `NNG_ECANCELED`: The operation was aborted.
-* `NNG_ECLOSED`: The socket _s_ is not open.
-* `NNG_EMSGSIZE`: The message is too large.
-* `NNG_ENOMEM`: Insufficient memory is available.
-* `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
-* `NNG_ESTATE`: The socket _s_ cannot send data in this state.
-* `NNG_ETIMEDOUT`: The send timeout expired.
-
-## SEE ALSO
-
-[nng_aio_get_msg][nng_aio_get_msg],
-[nng_aio_set_msg][nng_aio_set_msg],
-[nng_msg_alloc][nng_msg_alloc],
-[nng_strerror][nng_strerror],
-[nng_aio][nng_aio],
-[nng_msg][nng_msg],
-[nng_socket][nng_socket],
-[nng][nng]
-
-{{#include ../refs.md}}
diff --git a/docs/reference/src/sock/nng_send_aio.md b/docs/reference/src/sock/nng_send_aio.md
new file mode 100644
index 00000000..9f6b43c8
--- /dev/null
+++ b/docs/reference/src/sock/nng_send_aio.md
@@ -0,0 +1,75 @@
+# nng_send_aio
+
+## NAME
+
+nng_send_aio --- send message asynchronously
+
+## SYNOPSIS
+
+```
+#include <nng/nng.h>
+
+void nng_send_aio(nng_socket s, nng_aio *aio);
+```
+
+## DESCRIPTION
+
+The `nng_send_aio()` sends a [message][msg] using the
+[socket][socket] _s_ asynchronously.
+
+The message to send must have previously been set on the _aio_
+using the [`nng_aio_set_msg()`][nng_aio_set_msg] function.
+The function assumes ownership of the message.
+
+If the message was successfully queued for delivery to the socket,
+then the _aio_ will complete[^1], and [`nng_aio_result()`][nng_aio_result]
+will return zero. In this case the socket will dispose of the
+message when it is finished with it.
+
+[^1]:
+    This does _not_ indicate that the message was actually delivered, as it
+    may still be buffered in the sending socket, buffered in the receiving
+    socket, or in flight over physical media.
+
+If the operation fails for any reason (including cancellation or timeout),
+then the _aio_ {{i:callback}} will be executed and
+`nng_aio_result()` will return a non-zero error status.
+
+In this case, the callback has a responsibility to retrieve the message from
+the _aio_ with
+[`nng_aio_get_msg()`][nng_aio_get_msg] and dispose of it appropriately. [^2]
+(This may include retrying the send operation on the same or a different
+socket, or deallocating the message with [`nng_msg_free()`][nng_msg_free].)
+
+[^2]: Failure to do so will leak the memory associated with the message.
+
+> [!NOTE]
+> The semantics of what sending a message means varies from protocol to
+> protocol, so examination of the protocol documentation is encouraged.
+> Furthermore, some protocols may not support sending,
+> or may only permit sending when other conditions are met.
+
+## RETURN VALUES
+
+None. (The operation completes asynchronously.)
+
+## ERRORS
+
+- `NNG_ECANCELED`: The operation was aborted.
+- `NNG_ECLOSED`: The socket _s_ is not open.
+- `NNG_EMSGSIZE`: The message is too large.
+- `NNG_ENOMEM`: Insufficient memory is available.
+- `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
+- `NNG_ESTATE`: The socket _s_ cannot send data in this state.
+- `NNG_ETIMEDOUT`: The send timeout expired.
+
+## SEE ALSO
+
+[Asynchronous I/O][aio],
+[Messages][msg],
+[Sockets][socket],
+[nng_aio_get_msg][nng_aio_get_msg],
+[nng_aio_set_msg][nng_aio_set_msg],
+[nng_msg_alloc][nng_msg_alloc]
+
+{{#include ../refs.md}}
diff --git a/docs/reference/src/sock/nng_sendmsg.3.adoc b/docs/reference/src/sock/nng_sendmsg.3.adoc
deleted file mode 100644
index 004ae78d..00000000
--- a/docs/reference/src/sock/nng_sendmsg.3.adoc
+++ /dev/null
@@ -1,84 +0,0 @@
-# nng_sendmsg
-
-## NAME
-
-nng_sendmsg --- send message
-
-## SYNOPSIS
-
-```
-#include <nng/nng.h>
-
-int nng_sendmsg(nng_socket s, nng_msg *msg, int flags);
-```
-
-## DESCRIPTION
-
-The `nng_sendmsg()` sends message _msg_ using the socket _s_.
-
-If the function returns zero, indicating it has accepted the message for
-delivery, then the _msg_ is owned by the socket _s_, and the caller
-must not make any further use of it.
-The socket will free the message when it is finished.
-
-If the function returns non-zero, then it is the caller's responsibility
-to dispose of the _msg_, which may include freeing it, sending it to
-another socket, or simply trying again later.
-
-TIP: Using this function gives access to the message structure, and may
-offer more functionality than the simpler xref:nng_send.3.adoc[`nng_send()`] function.
-
-NOTE: The semantics of what sending a message means vary from protocol to
-protocol, so examination of the protocol documentation is encouraged.
-(For example, with a xref:nng_pub.7.adoc[_pub_] socket the data is broadcast, so that
-any peers who have a suitable subscription will be able to receive it using
-xref:nng_recv.3.adoc[`nng_recv()`] or a similar function.)
-Furthermore, some protocols may not support sending (such as
-xref:nng_sub.7.adoc[_sub_]) or may require other conditions.
-(For example, xref:nng_rep.7.adoc[_rep_] sockets cannot normally send data, which
-are responses to requests, until they have first received a request.)
-
-The _flags_ may contain the following value:
-
-`NNG_FLAG_NONBLOCK`::
-    The function returns immediately, regardless of whether
-    the socket is able to accept the data or not.
-    If the socket is unable to accept the data (such as if backpressure exists
-    because the peers are consuming messages too slowly, or no peer is present),
-    then the function will return with `NNG_EAGAIN`.
-    If this flag is not specified, then the function will block if such a
-    condition exists.
-
-
-NOTE: Regardless of the presence or absence of `NNG_FLAG_NONBLOCK`, there may
-be queues between the sender and the receiver.
-Furthermore, there is no guarantee that the message has actually been delivered.
-Finally, with some protocols, the semantic is implicitly `NNG_FLAG_NONBLOCK`,
-such as with xref:nng_pub.7.adoc[_pub_] sockets, which are best-effort delivery only.
-
-## RETURN VALUES
-
-This function returns 0 on success, and non-zero otherwise.
-
-## ERRORS
-
-* `NNG_EAGAIN`: The operation would block, but `NNG_FLAG_NONBLOCK` was specified.
-* `NNG_ECLOSED`: The socket _s_ is not open.
-* `NNG_EINVAL`: An invalid set of _flags_ was specified.
-* `NNG_EMSGSIZE`: The value of _size_ is too large.
-* `NNG_ENOMEM`: Insufficient memory is available.
-* `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
-* `NNG_ESTATE`: The socket _s_ cannot send data in this state.
-* `NNG_ETIMEDOUT`: The operation timed out.
-
-## SEE ALSO
-
-[nng_msg_alloc][nng_msg_alloc],
-[nng_recvmsg][nng_recvmsg],
-[nng_send][nng_send],
-[nng_strerror][nng_strerror],
-[nng_msg][nng_msg],
-[nng_socket][nng_socket],
-[nng][nng]
-
-{{#include ../refs.md}}
diff --git a/docs/reference/src/sock/nng_sendmsg.md b/docs/reference/src/sock/nng_sendmsg.md
new file mode 100644
index 00000000..31ad67de
--- /dev/null
+++ b/docs/reference/src/sock/nng_sendmsg.md
@@ -0,0 +1,82 @@
+# nng_sendmsg
+
+## NAME
+
+nng_sendmsg --- send message
+
+## SYNOPSIS
+
+```c
+#include <nng/nng.h>
+
+int nng_sendmsg(nng_socket s, nng_msg *msg, int flags);
+```
+
+## DESCRIPTION
+
+The `nng_sendmsg()` sends [message][msg] _msg_ using the [socket][socket] _s_.
+
+If the function returns zero, indicating it has accepted the message for
+delivery, then the _msg_ is owned by the socket _s_, and the caller
+must not make any further use of it.
+The socket will free the message when it is finished.
+
+If the function returns non-zero, then it is the caller's responsibility
+to dispose of the _msg_, which may include freeing it, sending it to
+another socket, or simply trying again later.
+
+> [!TIP]
+> Using this function gives access to the message structure, and may
+> offer more functionality than the simpler [`nng_send()`][nng_send] function. [^1] [^2]
+
+[^1]: It is also more efficient.
+[^2]: An asynchronous form of this function is available as [`nng_send_aio()`][nng_send_aio].
+
+> [!NOTE]
+> The semantics of what sending a message means vary from protocol to
+> protocol, so examination of the protocol documentation is encouraged.
+> Furthermore, some protocols may not support sending messages
+> or may require other conditions be met first before sending messages.
+
+The _flags_ may contain the following value:
+
+- {{i:`NNG_FLAG_NONBLOCK`}}:
+  The function returns immediately, regardless of whether
+  the socket is able to accept the data or not.
+  If the socket is unable to accept the data (such as if {{i:back-pressure}} exists
+  because the peers are consuming messages too slowly, or no peer is present),
+  then the function will return with `NNG_EAGAIN`.
+  If this flag is not specified, then the function will block if such a
+  condition exists.
+
+> [!NOTE]
+> Regardless of the presence or absence of `NNG_FLAG_NONBLOCK`, there may
+> be queues between the sender and the receiver.
+> Furthermore, there is no guarantee that the message has actually been delivered.
+> Finally, with some protocols, the semantic is implicitly `NNG_FLAG_NONBLOCK`,
+> such as with [_PUB_][pub] sockets, which are {{i:best-effort}} delivery only.
+
+## RETURN VALUES
+
+This function returns 0 on success, and non-zero otherwise.
+
+## ERRORS
+
+- `NNG_EAGAIN`: The operation would block, but `NNG_FLAG_NONBLOCK` was specified.
+- `NNG_ECLOSED`: The socket _s_ is not open.
+- `NNG_EINVAL`: An invalid set of _flags_ was specified.
+- `NNG_EMSGSIZE`: The value of _size_ is too large.
+- `NNG_ENOMEM`: Insufficient memory is available.
+- `NNG_ENOTSUP`: The protocol for socket _s_ does not support sending.
+- `NNG_ESTATE`: The socket _s_ cannot send data in this state.
+- `NNG_ETIMEDOUT`: The operation timed out.
+
+## SEE ALSO
+
+[Messages][msg],
+[Sockets][socket],
+[nng_msg_alloc][nng_msg_alloc],
+[nng_recvmsg][nng_recvmsg],
+[nng_send][nng_send]
+
+{{#include ../refs.md}}