ZeroMQ

How This Book Happened

When I set out to write a ØMQ book, we were still debating the pros and cons of forks and pull requests in the ØMQ community. Today, for what it’s worth, this argument seems settled: the “liberal” policy we adopted for libzmq in early 2012 broke our dependency on a single prime author and opened the floor to dozens of new contributors. More profoundly, it allowed us to move to a gently organic evolutionary model that was very different from the older forced-march model.

The reason I was confident this would work was that our work on the guide had, for a year or more, shown the way. True, the text is my own work, which is perhaps as it should be. Writing is not programming. When we write, we tell a story, and one doesn’t want different voices telling one tale; it feels strange.

For me the real long-term value of this project is the repository of examples: about 65,000 lines of code in 24 different languages. It’s partly about making ØMQ accessible to more people. People already refer to the Python and PHP example repositories—two of the most complete—when they want to tell others how to learn ØMQ. But it’s also about learning programming languages.

For example, here’s a loop of code in Tcl:

while {1} {
    # Process all parts of the message
    zmq message message
    frontend recv_msg message
    set more [frontend getsockopt RCVMORE]
    backend send_msg message [expr {$more?"SNDMORE":""}]
    message close
    if {!$more} {
        break ; # Last message part
    }
}

And the same ...