diffusion/src/node_modules/client/service-locator.js

Diffusion JavaScript client

var CommandHeader = require('services/command-header');
var logger = require('util/logger');

var log = logger.create("ServiceLocator");

function ServiceLocator(internalSession, serialisers, serviceAdapter) {

    this.obtain = function(service) {
        var requestSerialiser = serialisers.get(service.request);
        var responseSerialiser = serialisers.get(service.response);

        var reference = {
            send : function(req, callback) {
                callback = callback || function() {};

                var handler = {
                    onOpen : function(cid) {
                        var header = new CommandHeader(service.id, cid);

                        try {
                            serviceAdapter.sendRequest(header, req, requestSerialiser);
                        } catch (e) {
                            callback(e);
                            throw e;
                        }
                    },
                    onResponse : function(cid, input) {
                        var response;

                        try {
                            response = responseSerialiser.read(input);
                        } catch (e) {
                            log.debug("Failed to deserialise response from " + service.name, e.stack);

                            callback(e);
                            return true;
                        }

                        try {
                            callback(null, response);
                        } catch (e) {
                            log.debug("Request callback for service '" + service.name + "' threw an error", e.stack);

                            try {
                                callback(e);
                            } catch (e) {
                                log.debug("Failed to notify callback error for service '" + service.name + "'", e);
                            }
                        }

                        return true;
                    },
                    onDiscard : function(cid, err) {
                        callback(err);
                    }
                };
                var conversations = internalSession.getConversationSet();
                var cid = conversations.newConversation(handler, callback);
                
                return function() {
                    conversations.discard(cid, new Error("Cancelled"));
                };
            }
        };

        return reference;
    };
}

module.exports = ServiceLocator;