Impossible to lock sockjs version

Version: 7.3.2

Environment:

• Operating system: Android
• Browser: AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
• Node.js: 10.15.2

I’m seeing the following in the console:

E/browser ( 2462): Console: Uncaught Error: Incompatible SockJS! Main site
uses: "1.3.0", the iframe: "1.1.4". https://cdn.jsdelivr.net/sockjs/1/sockjs.min.js:2

If I understand the flow correctly, this is what happens:

1. on this device/browser combination, SockJS tries various transport strategies and eventually picks the iframe
2. it requests the iframe from the server
3. in https://github.com/sockjs/sockjs-node/blob/4c9f3009be13962b0785138ccdf527c5abe925f6/lib/iframe.js, the server generates the iframe, embedding the sockjs_url argument so the iframe knows where it has to load the library from
4. here: https://github.com/primus/primus/blob/bfc3f3180aeebe0c45019b8ec86b260935011e52/transformers/sockjs/server.js#L43 primus does not specify a sockjs_url, so
5. at https://github.com/sockjs/sockjs-node/blob/e2369c3d02c7e285ecbac409f3a4d0c8b72c39d3/lib/server.js#L31, sockjs picks the latest from jsdelivr as default

Unfortunately that means that sockjs client updates my happen at any time on end users’ devices, with no way for the developer to first test them.

I fixed this (perhaps simplistically) in https://github.com/sockjs/sockjs-node/blob/e2369c3d02c7e285ecbac409f3a4d0c8b72c39d3/lib/server.js#L31 by changing:

  this.service = sockjs.createServer();

Into:

  const SOCKJS_CLIENT_VERSION = require('sockjs-client/package.json').version
  this.service = sockjs.createServer({
    sockjs_url: 'https://cdn.jsdelivr.net/npm/sockjs-client@' + SOCKJS_CLIENT_VERSION + '/dist/sockjs.min.js'
  });

If that sounds like a good approach, I’ll prepare a PR.

[bard]

…and on third look, it seems that everything will go right by itself when the following change in sockjs-node gets released: https://github.com/sockjs/sockjs-node/commit/dc5a3d9ce809ed5e692bc1a5159546aa4824ee31

Currently, it’s the link https://cdn.jsdelivr.net/sockjs/1/sockjs.min.js that keeps resolving to sockjs-client 1.1.4 even when sockjs-node expects 1.3.0. The commit above changes the CDN link to https://cdn.jsdelivr.net/npm/sockjs-client@1/dist/sockjs.min.js which correctly resolves to sockjs-client 1.3.0.

Pinging @brycekahle … any chance for a release?

[lpinca]

Thank you @brycekahle. I’m closing as there is a workaround until a new release is cut.