YAWS Websocket Trouble

Question

I'm trying to get the YAWS websocket example from here running on my local. It's a basic ws-based echo server.

I have

• YAWS set up and running on localhost:8080 (direct from the Debian repos; no conf changes except pointing it to a new root directory)
• the code listing from the bottom of this page wrapped in <erl> tags saved as websockets_example_endpoint.yaws
• this page saved as index.yaws (I literally copy/pasted the view-source for it, saved it as that file and pointed the socket request at localhost:8080 rather than yaws.hyber.org).

When I visit localhost:8080/websockets_example_endpoint.yaws in-browser, it displays the text "You're not a web sockets client! Go away!", as expected. When I visit localhost:8080, it points me to the javascript enabled form, but the "Connect" button does nothing when clicked. If I leave index.yaws pointed at yaws.hyber.org instead of localhost:8080, the echo server connects and works exactly as expected.

Can anyone give me a hint as to what I'm doing wrong (or alternatively, point me to source for a working example)?

Answer 1

There is a gitbub project, I've created:
https://github.com/f3r3nc/yaws-web-chat/

This is also an example for embedding yaws and extended with group chat.

Note, that the standard of WebSocket is under development thus yaws and the browser should support the same WS version in order to work correctly.

yaws 1.91 works with Safari Version 5.1.1 (6534.51.22) but does not with Chrome (15.0.874.102) and probably not with (14.x).

Answer 2

For me the problem was I did not have the basic_echo_callback module file because I installed yaws using a package repository rather than building form source.

The error was evident if running yaws in interactive mode ´yaws -i´:

=ERROR REPORT==== 7-Dec-2016::21:33:49 ===
Cannot load callback module 'basic_echo_callback': nofile
=ERROR REPORT==== 7-Dec-2016::21:33:49 ===
Failed to start websocket process: nofileq

This is pretty much my process from scratch on Ubuntu 16.01:

sudo apt install yaws
cd ~
mkdir yaws
cd yaws

mkdir src
cd src
cd src wget https://github.com/klacke/yaws/raw/master/examples/src/basic_echo_callback.erl
cd ..

mkdir www
cd www
wget https://raw.githubusercontent.com/klacke/yaws/master/www/websockets_example_endpoint.yaws
wget http://yaws.hyber.org/websockets_example.yaws
cd ..

#set-up server config file...
vim yaws.conf

Mine looks like:

src_dir = /home/pocketsand/yaws/src
<server localhost>
  port = 8000
  listen = 127.0.0.1
  docroot = /home/pocketsand/yaws/www
</server>

Ensure endpoint is correct in the client:

vim www/websockets_example.yaws
...

Stop server if already running and start server with ´yaws -i´ and browse to: http://localhost:8000/websockets_example.yaws

It works because each time the server loads the configuration file it will compile any modules in the specified src directory. If other modules are missing for the other features they will also need to be downloaded.