Socket.io cannot create 2nd server, error: TypeError: wsModule.Server is not a constructor

[dennisat]

You want to:

• report a bug
• request a feature

Current behaviour

Cannot create two servers in the same node instance.

Steps to reproduce (if the current behaviour is a bug)

This test fails.

The wsServer2 cannot be created, we get a exception caught in the try catch block. The strange is that the 1st server, the wsServer1 is created with no exception.

Probably the creation should be done with different way... but how?

    var http = require('http');
    var engineIo = require('engine.io');
    var httpServer1;
    var httpServer2;
    var wsServer1;
    var wsServer2;
    describe('socket.io test basics', function () {
        it('should create server 1', function () {
            try {
                httpServer1 = http.createServer();
                wsServer1 = engineIo(httpServer1);
                httpServer1.listen(34001);
                expect(true).toBe(true);
            }
            catch (error) {
                console.error('cannot create server 1', error);
                expect(!!error).toBe(false);
            }
        });
        it('should create server 2', function () {
            try {
                httpServer2 = http.createServer();
                wsServer2 = engineIo(httpServer2);
                httpServer2.listen(34002);
                expect(true).toBe(true);
            }
            catch (error) {
                console.error('cannot create server 2', error);
                expect(!!error).toBe(false);
            }
        });
    });

The exception is this:

 TypeError: wsModule.Server is not a constructor
        at Server.Object.<anonymous>.Server.init (L:\myApp\node_modules\engine.io\lib\server.js:121:13)
        at new Server (L:\myApp\node_modules\engine.io\lib\server.js:65:8)
        at attach (L:\myApp\node_modules\engine.io\lib\engine.io.js:123:16)
        at Object.<anonymous>.module.exports (L:\myApp\node_modules\engine.io\lib\engine.io.js:24:19)
        at Object.it (L:\myApp\tests\socket.io.test.ts:26:25)
        at Object.asyncFn (L:\myApp\node_modules\jest-jasmine2\build\jasmine-async.js:68:30)
        at resolve (L:\myApp\node_modules\jest-jasmine2\build\queueRunner.js:38:12)
        at mapper (L:\myApp\node_modules\jest-jasmine2\build\queueRunner.js:31:21)
        at Promise.resolve.then.el (L:\myApp\node_modules\p-map\index.js:42:16)
        at process._tickCallback (internal/process/next_tick.js:103:7)

Expected behaviour

No errors. the 2nd server should be created as the first one did.

Setup

• OS: window
• browser: nodejs 7.2.0
• engine.io version: 2.0.3

Other information (e.g. stacktraces, related issues, suggestions how to fix)

[KevinW1998]

I've had the same issue. It seems that it is a issue with uws. If it fails to use uws it will fallback to ws (expection is thrown and catched). If this happens a second time the fallback fails (exception is not thrown) but the wsModule is set to undefined. Therefor the error.

A temporary workaround is to use the ws module.

[leaysgur]

I've had the same issue too.
And my case, it was because make command does not installed and failed to build uws.

My workaround is to modify code like

wsServer1 = engineIo(httpServer1, { wsEngine: 'ws' });

or wsEngine can be set by process.env.EIO_WS_ENGINE.
https://github.com/socketio/engine.io/blob/master/lib/server.js#L39

[darrachequesne]

Closed due to inactivity, please reopen if needed.