[erlang-questions] Programming Erlang: Chap 18, Websockets

Joe Armstrong erlang@REDACTED
Sun Jun 25 23:00:50 CEST 2017

Unfortunately cowboy (which I used) and the websockets standard have
changed since I wrote the book. I also used make and not rebar.

You've now run into what is one of the biggest problems in the
computer world - code that used to work no longer works despite the
fact the code itself has not been changed.

One way around this is to use zero dependencies - in fact several
programs I wrote 30 years ago in Erlang still work fine with no
changes because there are no external dependencies. (as an aside: this
is why I like code with zero external dependencies - it takes a lot
longer to write - but you don't have to support it into the future
when they things you depend upon change in a manner that is
incompatible manner)

In this example the underlying websockets protocol changed -
websockets its is a crazy mess - websockets should have provided raw
socket transport instead they chose to scramble the data in a weird
manner to avoid problems with badly written proxies.

The idea of "write once run anywhere" is a great goal - but we can't
even do this - "write once run forever with no changes to your code"
would be even better and things like NixOS are a step in the right

Welcome to the world of broken software.

In my opinion this (making sure software evolution does not break
existing functioning software)  is one of the biggest remaining
software problems - my guess is that this problem is getting worse
(due to the explosion in the numbers of programming languages,
libraries and frameworks and build systems) and will be even worse in
the IoT world.

Lots for you guys to work on :-)



On Sun, Jun 25, 2017 at 10:02 PM, 7stud <7stud@REDACTED> wrote:
> I'm having trouble running the demos for the ezwebframe.  I installed the old rebar (v. rebar3), but I'm getting the error:
>     {badmatch,{error,{not_started,ssl}}
> I'm on Mac OSX 10.10.5.  Here is my output:
> ===========
> ../ezwebframe-master$ gmake
> ...
> ....
> Erlang/OTP 19 [erts-8.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]
> a simple_demo of websockets....
> Load the page http://localhost:1456/ in your browser
> Starting:{ok,"/Users/7stud/erlang_programs/ezwebframe/ezwebframe-master/demos"}
> Eshell V8.2  (abort with ^G)
> 1> {"init terminating in do_boot",{{badmatch,{error,{not_started,ssl}}},[{ezwebframe,start_link,2,[{file,"src/ezwebframe.erl"},{line,22}]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
> init terminating in do_boot ()
> Crash dump is being written to: erl_crash.dump...done
> make[1]: *** [all] Error 1
> gmake: *** [Makefile:4: all] Error 2
> ===========
> Thanks for any help is solving this problem!
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