Mockup of module API that returns a handle which is then used to read partial responses as promises in a generator function.

blpapi.js

exports.Session.prototype.request =
    function(uri, name, request, label) {
        var current = Q.defer();
        var handle = {
            // When 'current' is set to 'undefined', it indicates that there are
            // no more responses and 'readResponse' should return 'undefined'.
            readResponse: function(cb) {
                return current ? current.promise : Q(undefined);
            }
        };
        this.session.request(uri, name, request, label, 
            function(err, response) {
                if (err) {
                    current.reject(err);
                } else {
                    current.resolve(response);
                    current = response ? Q.defer() : undefined;
                }
            });
        return handle;
    }

client.js

Q.async(function*() {
    // Setup session

    // Get a handle to the request.
    var requestHandle = session.request('//blp/apiflds',
        'FieldSearchRequest', { searchSpec: 'price' }, undefined);

    // Loop through any partial responses, stopping after final is returned.
    var response;
    while ((response = yield requestHandle.readResponse())) {
        console.log(util.inspect(response, { showHidden: true, depth: null }));
    }

    // Stop and destroy the session.
})().done();