How to handle/create middleware for server side session management in a core node.js /non express.js project. I can find modules for express based project but not for core node.js. Please suggest me any modules or middleware for non express.js project.
Session management can be implemented via database (MySQL, MongoDB, Redis etc.) or some local cache.
The main logic behind sessions - is object with data.
So you can provide user on first interaction with some random id, like uuid.
And save it to some module, which looks like this:
class OwnSession(){
constructor(){
this.sessions = {};
}
getUser(sessionId){
return this.sessions[sessionId];
}
setUser(sessionId, userData){
if(this.sessions[sessionId]){
Object.assign(this.sessions[sessionId], userData);
return;
}
this.sessions[sessionId] = userData;
}
}
// We export here new OwnSession() to keep singleton across your project.
module.exports = new OwnSession();
And then, in any module you require OwnSession and call the method.
Related
How can I achieve concurrency in this situation so Node Module can serve multiple users?
I'm developing two pieces of a codebase for a client application.
Node App
Node Module (collection of classes)
Node app provides credentials for user1 to Node Module that in turns gets the access_token and then uses (both token and credentials) for subsequent calls.
I prefer that Node Module takes care of managing the access token and credentials for all calls but then it limits to 1 user since node runs in a single process.
One of my Node module classes looks like this, (see the issue) I'm providing credentials and authentication (token) to each function call besides other params (not a good interface). Wondering if this can be any better so I can have cleaner interface of each function call besides achieving concurrency.
var Entity = function() {};
Entity.prototype.requestList = function(credentials, authentication, publication, entityType) {
return new Proimse(function(resolve, reject){
});
};
module.exports = new Entity();
Edit
One solution that just came to me is to return the access_token (3rd party token) besides the authToken (my app token) back to the client, so clients cache them and send them along with each subsequent request so server side code doesn't have to maintain or manage it. Concurrency achieved.
I am trying to setup a project workflow in loopback which utilizes 2 different projects which include a base project.
Here is what I want to do:
loopback-project-1
|__loopback-project-2
|__loopback-project-3
So the idea would be to have all my basic tasks like authentication and authorization in loopback-project-1 and then include that in loopback-project-2 and loopback-project-3 to save me from re-creating that logic in the other projects. In other words, I need some way to share models across multiple loopback applications without having to duplicate code.
I tried creating a bootscript to try to load the other application as express middleware but that only seems to expose the REST API; NOT the models.
Here is my bootscript:
var boot = require('loopback-boot');
module.exports = function(app) {
app.use('/base', require('../../../loopback-project-1/server/server'));
boot(app, '../../../loopback-project-1/server/server', function(err) {
if (err) throw err;
});
};
Note: This bootscript would be included in loopback-project-2 and loopback-project-3.
My end goal is to be able to use loopback as the primary development stack for a multi-application architecture with a heavy focus on code re-use. The idea would be to include loopback-project-1 into other projects which would automatically include base models as well as any base functionality which resides in loopback-project-1; such as authentication / authorization.
Let me know how this can be accomplished.
Thanks
I am using mongodb-native-driver in express.js app. I have around 6 collections in the database, so I have created 6 js files with each having a collection as a javascript object (e.g function collection(){}) and the prototypes functions handling all the manipulation on those collections. I thought this would be a good architecture.
But the problem I am having is how to connect to the database? Should I create a connection in each of this files and use them? I think that would be an overkill as the connect in mongodb-native-driver creates a pool of connections and having several of them would not be justified.
So how do I create a single connection pool and use it in all the collections.js files? I want to have the connection like its implemented in mongoose. Let me know if any of my thought process in architecture of the app is wrong.
Using Mongoose would solve these problems, but I have read in several places thats it slower than native-driver and also I would prefer a schema-less models.
Edit: I created a module out of models. Each collection was in a file and it took the database as an argument. Now in the index.js file I called the database connection and kept a variable db after I got the database from the connection. (I used the auto-reconnect feature to make sure that the connection wasn't lost). In the same index.js file I exported each of the collections like this
exports.model1 = require('./model1').(db)
exprorts.model2 = require('./model2').(db)
This ensured that the database part was handled in just one module and the app would just call function that each model.js file exported like save(), fincdbyid() etc (whatever you do in the function is upto you to implement).
how to connect to the database?
In order to connect using the MongoDB native driver you need to do something like the following:
var util = require('util');
var mongodb = require('mongodb');
var client = mongodb.MongoClient;
var auth = {
user: 'username',
pass: 'password',
host: 'hostname',
port: 1337,
name: 'databaseName'
};
var uri = util.format('mongodb://%s:%s#%s:%d/%s',
auth.user, auth.pass, auth.host, auth.port, auth.name);
/** Connect to the Mongo database at the URI using the client */
client.connect(uri, { auto_reconnect: true }, function (err, database) {
if (err) throw err;
else if (!database) console.log('Unknown error connecting to database');
else {
console.log('Connected to MongoDB database server at:');
console.log('\n\t%s\n', uri);
// Create or access collections, etc here using the database object
}
});
A basic connection is setup like this. This is all I can give you going on just the basic description of what you want. Post up some code you've got so far to get more specific help.
Should I create a connection in each of this files and use them?
No.
So how do I create a single connection pool and use it in all the collections.js files?
You can create a single file with code like the above, lets call it dbmanager.js connecting to the database. Export functions like createUser, deleteUser, etc. which operate on your database, then export functionality like so:
module.exports = {
createUser: function () { ; },
deleteUser: function () { ; }
};
which you could then require from another file like so:
var dbman = require('./dbmanager');
dbman.createUser(userData); // using connection established in `dbmanager.js`
EDIT: Because we're dealing with JavaScript and a single thread, the native driver indeed automatically handles connection pooling for you. You can look for this in the StackOverflow links below for more confirmation of this. The OP does state this in the question as well. This means that client.connect should be called only once by an instance of your server. After the database object is successfully retrieved from a call to client.connect, that database object should be reused throughout the entire instance of your app. This is easily accomplished by using the module pattern that Node.JS provides.
My suggestion is to create a module or set of modules which serves as a single point of contact for interacting with the database. In my apps I usually have a single module which depends on the native driver, calling require('mongodb'). All other modules in my app will not directly access the database, but instead all manipulations must be coordinated by this database module.
This encapsulates all of the code dealing with the native driver into a single module or set of modules. The OP seems to think there is a problem with the simple code example I've posted, describing a problem with a "single large closure" in my example. This is all pretty basic stuff, so I'm adding clarification as to the basic architecture at work here, but I still do not feel the need to change any code.
The OP also seems to think that multiple connections could possibly be made here. This is not possible with this setup. If you created a module like I suggest above then the first time require('./dbmanager') is called it will execute the code in the file dbmanager.js and return the module.exports object. The exports object is cached and is also returned on each subsequent call to require('./dbmanager'), however, the code in dbmanager.js will only be executed the first require.
If you don't want to create a module like this then the other option would be to export only the database passed to the callback for client.connect and use it directly in different places throughout your app. I recommend against this however, regardless of the OPs concerns.
Similar, possibly duplicate Stackoverflow questions, among others:
How to manage mongodb connections in nodejs webapp
Node.JS and MongoDB, reusing the DB object
Node.JS - What is the right way to deal with MongoDB connections
As accepted answer says - you should create only one connection for all incoming requests and reuse it, but answer is missing solution, that will create and cache connection. I wrote express middleware to achieve this - express-mongo-db. At first sight this task is trivial, and most people use this kind of code:
var db;
function createConnection(req, res, next) {
if (db) { req.db = db; next(); }
client.connect(uri, { auto_reconnect: true }, function (err, database) {
req.db = db = databse;
next();
});
}
app.use(createConnection);
But this code lead you to connection-leak, when multiple request arrives at the same time, and db is undefined. express-mongo-db solving this by holding incoming clients and calling connect only once, when module is required (not when first request arrives).
Hope you find it useful.
I just thought I would add in my own method of MongoDB connection for others interested or having problems with different methods
This method assumes you don't need authentication(I use this on localhost)
Authentication is still easy to implement
var MongoClient = require('mongodb').MongoClient;
var Server = require('mongodb').Server;
var client = new MongoClient(new Server('localhost',27017,{
socketOptions: {connectTimeoutMS: 500},
poolSize:5,
auto_reconnect:true
}, {
numberOfRetries:3,
retryMilliseconds: 500
}));
client.open(function(err, client) {
if(err) {
console.log("Connection Failed Via Client Object.");
} else {
var db = client.db("theDbName");
if(db) {
console.log("Connected Via Client Object . . .");
db.logout(function(err,result) {
if(!err) {
console.log("Logged out successfully");
}
client.close();
console.log("Connection closed");
});
}
}
});
Credit goes to Brad Davley which goes over this method in his book (page 231-232)
Note: Please read the edited portion of this post before answering, it might save you time and answers one of my questions.
The problem I'm having is pretty simple but I'm pretty new to this overall and I'm having issues figuring out how to implement a mongodb database connection properly in a node/express app.
I'm using express 3.x and am basing my app layout around this project supplied by the author of Express:
https://github.com/expressjs/express/tree/d8caf209e38a214cb90b11ed59fd15b717b3f9bc/examples/blog (now removed from repo)
I have no interest in making a blog however the way the app is structured appears to be quite nice. The routes are separated and everything is organized nicely.
My problem is I might have 5-6 different route js files and each route js file might have anywhere between 1 and 15 routes; of those routes 1 or 15 might want to access the db.
So my problem is it seems like a really terrible idea to do a db.open(...) every single time I want to query the db. I should mention at this point I'm using the native mongo-db driver (npm install mongodb).
I would also need to include a file like this:
http://pastebin.com/VzFsPyax
...in all of those route files and all of my model files. Then I'm also dealing with dozens upon dozens of open connections.
Is there a way I can structure my app in such a way where I only make 1 connection and it stays open for the duration of the session (having a new one made every request would be bad too)?
If so, how can I do this? If you know the answer please post a code sample using tj's blog app (the one linked earlier in this post) structure as a base guide. Basically have a way where the routes and models can use the db freely while being in separate files than the db open code.
Thanks.
EDIT
I made some progress on solving one of my issues. If you look at tj's blog example he initializes his routes in the app.js like so:
require('./routes/site')(app);
require('./routes/post')(app);
And in the routes js file it starts like this:
module.exports = function(app){
I stumbled on a project earlier today where I saw someone pass 2 variables in the modules.exports call -> function(app, db). Then figured wow could it be that easy, do I need to just adjust my routes to be (app, db) too? Yeah, it seems so.
So now part 1 of the problem is solved. I don't have to require a mongo.js file with the connection boilerplate in every route file. At the same time it's flexible enough where I can decide to pick and choose which route files pass a db reference. This is standard and has no downside right?
Part 2 of the problem (the important one unfortunately) still exists though.
How can I bypass having to do a db.open(...) around every query I make and ideally only make a connection once per session?
Other solution is to pass database to the router via request, like this:
app.js
var db = openDatabase();
var app = express();
app.all('*', function(request, response, next)
{
request.database = db;
next();
});
app.get('/api/user/:id', Users.getByID);
users.js
var Users =
{
getByID: function(request, response)
{
request.database.collection('users').findOne(...)
response.send(user);
}
};
module.exports = Users;
I made a very simple module hub for this case that replaces the use of a global space.
In app.js you can create db connection once:
var hub = require('hub');
hub.db = new Db('foobar', new Server('10.0.2.15', 27017, {}), {native_parser: false});
And use it from any other files:
var hub = require('hub');
// hub.db - here link to db connection
This method uses a feature of 'require'. Module is only loaded for the first time and all the other calls gets a reference to an already loaded instance.
UPDATE
That's what I mean:
In main file like app.js we create Db connection, open it and store into hub:
app.js:
var hub = require('hub');
hub.mongodb = require('mongodb');
hub.mongodbClient = new hub.mongodb.Db('foobar', new hub.mongodb.Server('10.0.2.15', 27017, {}), {native_parser: false});
hub.mongodbClient.open(function(error) {
console.log('opened');
});
Now in any other file (message for example) we have access to opened connection and can simple use it:
message.js:
var hub = require('hub');
var collection = new hub.mongodb.Collection(hub.mongodbClient, 'message');
module.exports.count = function(cb) {
collection.count({}, function(err, count) {
cb(err, count);
});
};
Really silly. In the documentation it seems like db.open requires to be wrapped around whatever is using it, but in reality you can use it without a callback.
So the answer is to just do a db.open() in your database connection module, app.js file or where ever you decide to setup your db server/connection.
As long as you pass a reference to the db in the files using it, you'll have access to an "opened" db connection ready to be queried.
I created my Schema's in my models/mymodel.js file. I also have my models in there as well as my methods.
How do I export them into my routes?
// route.js
var mongoose = require("mongoose");
var Posts = mongoose.model("posts")
...
Ensure that you set up a bootstrap mechanism that runs all your model files. Once that is done you should have called mongoose.model("name", Model) for a set of models.
This has cached those models in mongoose internally. So you can just call mongoose.model("name") anywhere you want.
The only thing that's important is order of execution. The model & schemas need to be registered before you run your routes.
This is as a simple as :
// create app
var app = express.createServer(...);
// do stuff with app
var files = fs.readdirSync("models");
files.forEach(function(file) {
require("models/" + file);
});
var routes = fs.readdirSync("routes");
routes.forEach(function(route) {
require("routes/" + route)(app);
});
app.listen(80);
Note that normally readdirSync is evil but it's ok to execute blocking calls at startup time (like require) before your listen to your server
Mongoose creates a singleton when you require() it, and subsequent calls return the same instance.
So as long as you require mongoose when your app inits, then define your models, they will be available in any other file where you require mongoose as described by Raynos.
Unless you want to manage connections to the db server manually, it's also a good idea to call mongoose.connect('...') in your app init; the connection will persist across requests.