ZMQ_ROUTER_NOTIFY doesn't have a context and doesn't play nice with protocols. with ZMQ_DISCONNECT_MSG we can set it to a protocol message, like DISCONNECT in majordomo. Router will send it when a peer is disconnected. Another advantage of ZMQ_DISCONNECT_MSG is that it also works on inproc.
Together with ZMQ_HEARTBEAT it allows to build very reliable protocols, and much simpler as well.
When using ZMQ_HEARTBEAT one still needs to implement application-level heartbeat in order to know when to send a hello message.
For example, with the majordomo protocol, the worker needs to send a READY message when connecting to a broker. If the connection to the broker drops, and the heartbeat recognizes it the worker won't know about it and won't send the READY msg.
To solve that, the majordomo worker still has to implement heartbeat. With this new option, whenever the connection drops and reconnects the hello message will be sent, greatly simplify the majordomo protocol, as now READY and HEARTBEAT can be handled by zeromq.
* Allow CMAKE to generate ws and wss transports
I guess there is little use of just ws transport, so by default
GnuTLS (and libsodium) are enabled
* cmake libzmq including wss transport (ubuntu 19.10 and ubuntu 19.10 + wsl 1.0)
test_security_fails (libsodium assert !?)
* updated relicense
* make external libs gnutls nss sodium optional
* #ifdef WSS classes and functions, build test*ws* only if correct libs are included, warning if libs not present
* make libsodium optional
* cmake fix tests TIPC transport
* clang-format pointed out a wrongly placed #ifdef
* GnuTLS before 3.6.7 is not safe
* msvc doesn't agree with strlen in array declaration, test_socks now at least compiles on windows
* windows: libsodium build fails, missing include dirs set by env var
* ws transport test only works when GnuTLS is found
* Fixed condition to use NSS / built in SHA1, so that test_ws_transport should now pass, also when GnuTLS is not found
Some ifdefs in condition checking may cause problem in some compiler or
static analyzers. When PGM and NORM both are disabled, some condition
will be derived as false || false.
Solution: Splitted condition checking for every ifdef conditions
Conditinoal compile for OPENPGM and NORM is mixed.
Also found few codes which needs conditional compile but not applied.
Solution: Apply conditional compile preprocessors
Solution: a new socket type, called PEER. Very similar to SERVER, but can only connect to other PEERs. Also a new zmq_connect_peer method, that connect and return a routing-id in thread-safe and atomic operation
Solution: Allow ZMQ_PUB and ZMQ_PUSH sockets types for the monitoring.
This way someone could create a ZMQ_PULL socket connected to multiple
monitoring sockets at the same time.
Solution: add API and ZMQ_EVENT_PIPES_STATS event which generates 2
values, one for the egress and one for the ingress pipes respectively.
Refactor the events code to be able to send multiple values.
Solution: change back the indentifier endpoint to the one passed by the
user rather than the resolved one, otherwise when the user passes the
same string to the disconnect call they do not match anymore
Solution: if a multi-part message cannot be delivered by a PUSH socket
because the pipe is broken mid-way, drop the rest of the frames so that
the atomicity property is not broken.
