Send error message to client

[adlerparnas]

I believe that if you returned an error as a response to a call, you should be able to read the error on the client

[speigg]

👍

[speigg]

Actually this is still wrong, look at the spec:
https://github.com/wamp-proto/wamp-proto/blob/master/spec/basic.md#invocation-error

[ERROR, INVOCATION, INVOCATION.Request|id, Details|dict, Error|uri]
or

[ERROR, INVOCATION, INVOCATION.Request|id, Details|dict, Error|uri, Arguments|list]
or

[ERROR, INVOCATION, INVOCATION.Request|id, Details|dict, Error|uri, Arguments|list, ArgumentsKw|dict]

So, "wamp.error.callee_failure" should be replaced by err, and the additional parameters should also be added to the error message (args and kwargs, if they exists)

[speigg]

I believe this would be correct:

var resultCallback = function(err, args) {
        var msg;
        if (err) {
            msg = [
                WAMP.ERROR,
                WAMP.CALL,
                callId,
                {},
                err
            ];
        } else {
            msg =  [
                WAMP.RESULT,
                callId,
                {},
            ];
        }
        // Manage optional parameters args + kwargs
        for(var i = 0; i < args.length && i < 2; i++) {
            msg.push(args[i]);
        }
        session.send(msg);
};

[speigg]

The other problem with sending errors is in handlers[WAMP.ERROR]

handlers[WAMP.ERROR] = function(session, msg) {
    var requestType = msg.shift();
    var requestId = msg.shift();
    var details = msg.shift();
    var errorUri = msg.shift();
    var args = msg.shift() || [];
    var kwargs = msg.shift() || {};

    var err = new Error(details);   // <--- this line
    if (requestType === WAMP.INVOCATION) {
        // An invocation failed
        var invId = requestId;
        this.resrpc(invId, err, args); // <--- only err and args objects passed?
    }

}

Several problems:

1. details are converted to an Error object, so this immediately becomes unusable for routing to the Caller (Error objects are not meaningfully JSON.stringified).
2. errorUri and kwargs are ignored? surely these should also be routed to the Caller.