wsc.q

WebSocket Client Connection Library

This library provides the ability to create client WebSocket connections.

.wsc.connect

Attempts to create a WebSocket client connection to the specified URL.

Prior to attempting a connection, the function will:

1. Ensure that the .z.ws handler function is set
2. The URL has a valid WebSocket scheme (either ws:// or wss://)
3. If a TLS-encrypted WebSocket is requested, ensure TLS is available on the current process

Example

/ Define a kdb process as an echo WebSocket target
/   $QHOME/l64/q -p 12345
/   .z.ws:{ neg[.z.w] x }

q) .wsc.connect "ws://localhost:12345"
2020.05.22 15:04:59.719 INFO pid-669 jas 0 Attempting to connect to ws://localhost:12345 via WebSocket
2020.05.22 15:04:59.723 INFO pid-669 jas 0 Connected to ws://localhost:12345 via WebSocket [ Handle: 4 ]
4i

q) neg[4] .j.j enlist[`time]!enlist .z.p

q)"{\"time\":\"2020-05-22T15:05:11.220108000\"}"

Options

.ws.cfg.logToIpc

If this option is set to true, all new connections established via .wsc.connect will be added to the .ipc.outbound connection tracking table, which is part of the ipc library.

Configuring TLS

kdb+ only searches for libssl.so in the library path, therefore you may need to create a symlink from the OpenSSL 1.0.x library present in your OS to libssl.so.

For example on Ubuntu (as root):

# cd /usr/lib/x86_64-linux-gnu/
# ls -l libssl*
-rw-r--r-- 1 root root 426232 Feb 26  2019 libssl.so.1.0.0
-rw-r--r-- 1 root root 577312 Nov 12  2019 libssl.so.1.1

# ln -s libssl.so.1.0.0 libssl.so

# ls -l libssl*
lrwxrwxrwx 1 root root     15 May 22 11:42 libssl.so -> libssl.so.1.0.0
-rw-r--r-- 1 root root 426232 Feb 26  2019 libssl.so.1.0.0
-rw-r--r-- 1 root root 577312 Nov 12  2019 libssl.so.1.1

You may also need to disable server certificate validation, again depending on your OS (although this is not recommended in Production).

To disable (for kdb+ processes only):

export KX_SSL_VERIFY_SERVER=NO