WebFund 2014W Lecture 5 - Revision history

Awylie: Lecture 5 Notes

2014-02-06T02:19:03Z

Lecture 5 Notes

Gkadri at 23:30, 4 February 2014

2014-02-04T23:30:28Z

Gkadri at 23:29, 4 February 2014

2014-02-04T23:29:23Z

← Older revision		Revision as of 23:29, 4 February 2014
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	o App.use(express.json());		o App.use(express.json());
	Nothing really happens		Nothing really happens


	• When deleting		• When deleting
	o App.use(express.urlencoded());		o App.use(express.urlencoded());

Gkadri at 23:28, 4 February 2014

2014-02-04T23:28:58Z

← Older revision		Revision as of 23:28, 4 February 2014
Line 33:		Line 33:
	• Session-demo:		• Session-demo:
	• Different users have different sessions and the server knows about the different sessions. The server is keeping track of state per user that is logged in.		• Different users have different sessions and the server knows about the different sessions. The server is keeping track of state per user that is logged in.
	• The state is representation of what is on the server but it is also a reflection of which session has been identified to the server.		• The state is a representation of what is on the server but it is also a reflection of which session has been identified to the server.
	• HTTP is a stateless protocol. Stateless means that each request that goes to the browser is independent of every other request.		• HTTP is a stateless protocol. Stateless means that each request that goes to the browser is independent of every other request.
	• When you make a request, your browser does not only send URL. It also sends a request with a lot of other properties. This is also a part of the HTTP protocol.(Look under the “Header” tab of the “Network” section in the Firefox console).		• When you make a request, your browser does not only send URL. It also sends a request with a lot of other properties. This is also a part of the HTTP protocol.(Look under the “Header” tab of the “Network” section in the Firefox console).

Gkadri at 23:26, 4 February 2014

2014-02-04T23:26:47Z

← Older revision		Revision as of 23:26, 4 February 2014
Line 4:		Line 4:
	* [http://dl.cuol.ca/capture/Anil.Somayaji/COMP_2406_2014W_Lecture_5_-_20140122_151202_27.mp4 original at CUOL] (mp4)		* [http://dl.cuol.ca/capture/Anil.Somayaji/COMP_2406_2014W_Lecture_5_-_20140122_151202_27.mp4 original at CUOL] (mp4)
	* [http://homeostasis.scs.carleton.ca/~soma/webfund-2014w/lectures/comp2406-2013f-lec05-22Jan2014.mp4 original at homeostasis] (mp4)		* [http://homeostasis.scs.carleton.ca/~soma/webfund-2014w/lectures/comp2406-2013f-lec05-22Jan2014.mp4 original at homeostasis] (mp4)


			• To create an empty object we use:

			o Var car = { speed: “slow”};
			o Var tesla = object.create(car);
			• To check the properties of the object:
			o Tesla.speed
			o ‘slow’
			• To assign a different value to the speed property:
			o Tesla.speed = “fast”;
			o ‘fast’
			• To assign a default value to a prototype object property:
			o Car.colour = “white”;
			o ‘white’
			• To check:
			o Car
			o { speed: ‘slow’, colour: ‘white’ }
			o Tesla
			o { speed: ‘fast’ }
			• Note that the object “tesla” does not have the property colour but its prototype has it.
			o Object.getPrototypeOf(tesla);
			o { speed: ‘slow’,
			o colour: ‘white’
			o wheels: 4 }
			• Every object in JavaScript has a prototype that can be accessed by:
			o Object.prototype
			• Session-demo:
			• Different users have different sessions and the server knows about the different sessions. The server is keeping track of state per user that is logged in.
			• The state is representation of what is on the server but it is also a reflection of which session has been identified to the server.
			• HTTP is a stateless protocol. Stateless means that each request that goes to the browser is independent of every other request.
			• When you make a request, your browser does not only send URL. It also sends a request with a lot of other properties. This is also a part of the HTTP protocol.(Look under the “Header” tab of the “Network” section in the Firefox console).

			• A User-Agent string is a part of the HTTP request. It is supposed to tell the server what kind of browser you are using.
			• A cookie is some bit of data that is sent somewhere and is expect to be returned later and is not to be processed or “eaten” by the other side.
			• Status code: every HTTP request that comes in to a server will generate a response code. (i.e. response code 200 means o.k. Response code 404 means page not found and 302 means page moved temporarily).
			• Node is a general web application execution platform. Express is a framework for it.
			• The following function takes ‘Comp 4106 rules!’ as a secret argument to encrypt the user session and to generate the valid cookies. The cookies must be made to be hard to reverse by others.
			o app.use(express.cookieParser(‘Comp 2406 rules!’));
			• The following function uses the cookie parser in order to maintain sessions. It is the session identifier. Every time we do a “get” a cookies comes along with it and the user is identified:
			o app.use(express.session());
			• Cookies can be specified with different life times. Some cookies are specified with session only life time. Some other cookies are specified to live for hours, days or years.


			• /routes/Index.js:
			• When the user enters the username, the incoming request has a session sub-object which is defined by the session layer of Express
			• If the session object has a username as a property, the user is already logged in

			o Function index (req, res) {
			o If (req.session.username){
			o res.redirect(“/users”);
			o } else {
			o res.render(‘index’), { title: ‘COMP 2406 Session Demo’,
			o error: req.query.error });
			o }
			o }

			• In the following code we set the username variable by (req.session.username)

			o Function login (req, res) {
			o Var username = req.body.username;
			o Req.session.username = username;
			o loggedInUsers [username] = LoggedIn;
			o res.redirect (“/users”)
			o }

			• Note that the user name came from the req.body object.
			• (req.body.username) is a part of the form.
			• The form “post” sends the user name to the server (this can be viewed under the “params” tab of the “network” section in the console.
			• Next we save it to the session by
			o Req.session.username = username;


			• When you ever see a line like:
			o Form (action=”/login” , method=”post”)

			In /views/index.jade
			You should expect to see a corresponding route like:
			o App.post(“/login”, routes.login);
			o App.post(“/logout”, routes.logout)
			In app.js
			Otherwise there will be a 404 error (page not found).

			• When deleting
			o App.use(express.json());
			Nothing really happens
			• When deleting
			o App.use(express.urlencoded());
			The (req.session.username) condition in index.js (as shown below) fails and it won’t consider the user logged in.
			o Function users (req, res) {
			o If(req.session.username){
			o res/render (“account.jade”, {username: req.session.username,
			o title:”Account”,
			o loggedInUsers: loggedInUsers});
			o } else {
			o res.redirect(“/?error=Not Logged In”);
			o }
			o };

Soma: Created page with "Video from the lecture given on Jan 22, 2014 is now available from multiple sources: * [http://www.screencast.com/t/Aypl5x4M small at screencast.com] (flash/mp4) * [http://www..."

2014-01-24T17:20:02Z

Created page with "Video from the lecture given on Jan 22, 2014 is now available from multiple sources: * [http://www.screencast.com/t/Aypl5x4M small at screencast.com] (flash/mp4) * [http://www..."

New page

Video from the lecture given on Jan 22, 2014 is now available from multiple sources:
* [http://www.screencast.com/t/Aypl5x4M small at screencast.com] (flash/mp4)
* [http://www.screencast.com/t/gykjMNBv8c large at screencast.com] (flash/mp4)
* [http://dl.cuol.ca/capture/Anil.Somayaji/COMP_2406_2014W_Lecture_5_-_20140122_151202_27.mp4 original at CUOL] (mp4)
* [http://homeostasis.scs.carleton.ca/~soma/webfund-2014w/lectures/comp2406-2013f-lec05-22Jan2014.mp4 original at homeostasis] (mp4)

← Older revision		Revision as of 23:30, 4 February 2014
Line 33:		Line 33:
	• Session-demo:		• Session-demo:
	• Different users have different sessions and the server knows about the different sessions. The server is keeping track of state per user that is logged in.		• Different users have different sessions and the server knows about the different sessions. The server is keeping track of state per user that is logged in.

	• The state is a representation of what is on the server but it is also a reflection of which session has been identified to the server.		• The state is a representation of what is on the server but it is also a reflection of which session has been identified to the server.

	• HTTP is a stateless protocol. Stateless means that each request that goes to the browser is independent of every other request.		• HTTP is a stateless protocol. Stateless means that each request that goes to the browser is independent of every other request.

	• When you make a request, your browser does not only send URL. It also sends a request with a lot of other properties. This is also a part of the HTTP protocol.(Look under the “Header” tab of the “Network” section in the Firefox console).		• When you make a request, your browser does not only send URL. It also sends a request with a lot of other properties. This is also a part of the HTTP protocol.(Look under the “Header” tab of the “Network” section in the Firefox console).

	• A User-Agent string is a part of the HTTP request. It is supposed to tell the server what kind of browser you are using.		• A User-Agent string is a part of the HTTP request. It is supposed to tell the server what kind of browser you are using.

	• A cookie is some bit of data that is sent somewhere and is expect to be returned later and is not to be processed or “eaten” by the other side.		• A cookie is some bit of data that is sent somewhere and is expect to be returned later and is not to be processed or “eaten” by the other side.

	• Status code: every HTTP request that comes in to a server will generate a response code. (i.e. response code 200 means o.k. Response code 404 means page not found and 302 means page moved temporarily).		• Status code: every HTTP request that comes in to a server will generate a response code. (i.e. response code 200 means o.k. Response code 404 means page not found and 302 means page moved temporarily).

	• Node is a general web application execution platform. Express is a framework for it.		• Node is a general web application execution platform. Express is a framework for it.

	• The following function takes ‘Comp 4106 rules!’ as a secret argument to encrypt the user session and to generate the valid cookies. The cookies must be made to be hard to reverse by others.		• The following function takes ‘Comp 4106 rules!’ as a secret argument to encrypt the user session and to generate the valid cookies. The cookies must be made to be hard to reverse by others.
	o app.use(express.cookieParser(‘Comp 2406 rules!’));		o app.use(express.cookieParser(‘Comp 2406 rules!’));
Line 49:		Line 56:

	• /routes/Index.js:		• /routes/Index.js:

	• When the user enters the username, the incoming request has a session sub-object which is defined by the session layer of Express		• When the user enters the username, the incoming request has a session sub-object which is defined by the session layer of Express

	• If the session object has a username as a property, the user is already logged in		• If the session object has a username as a property, the user is already logged in

Line 71:		Line 80:

	• Note that the user name came from the req.body object.		• Note that the user name came from the req.body object.

	• (req.body.username) is a part of the form.		• (req.body.username) is a part of the form.

	• The form “post” sends the user name to the server (this can be viewed under the “params” tab of the “network” section in the console.		• The form “post” sends the user name to the server (this can be viewed under the “params” tab of the “network” section in the console.

	• Next we save it to the session by		• Next we save it to the session by
	o Req.session.username = username;		o Req.session.username = username;