Web fundamentals part 1

Bozhidar BoshnakovIvaiylo Kadiyski

FFW

This presentation and its contents are property of FFW.

Today’s Agenda01020304

Evolution and components of webWeb communicationSite / server relationQ&A

Evolution of web

1989, CERN, Tim Berners-LeeThree fundamental technologies:

HTMLURI (Uniform Resource Identifier)URL (Unified Resource Location)

HTTP / HTTPS

Тhe story starts…

Web 1.0>Old media model>It all started with a simple idea>Just put content in the web>Low content variety>Limited content>Limited creativity>Limited business>10 000 editors serve 500 000 000 internet users

Web 2.0>User generated content>New platforms allow users to generate content themselves (YouTube, Wiki, Facebook, Blogs)

>Everyone can publish!>Web 2.0 can be described in 3 parts:

- Rich Internet application (RIA)>Web-oriented architecture (WOA)

- Feeds, RSS, Web Services, etc.>Social web

Web 3.0>Web 3.0 is where the computer is generating new information, rather than humans

>All the new web 3.0 concepts can be divided into 4 parts:

- Semantic web- Artificial intelligence- Personalization- Mobility

Components of web

What is website?Collection of related web pages containing web resources.Common navigation between web pages.A website is hosted on at least one web server.Accessible via a network.All publicly accessible websites collectively constitute the World Wide Web.

What is webpage?Document of information resource that is suitable for the World Wide WebCan be accessed through a web browser and displayed on different devicesHTML/XHTML formatWeb pages frequently refer to other resources such as CSS, JS

What is web application?A web application or web app is any software that runs in a web browser. It is created in a browser-supported programming language (such as the combination of JavaScript, HTML and CSS) and relies on a web browser to render the application.

What is web application?Next level web sitesHigh interactivityHigh accessibility (Cloud)AJAX, Silverlight, Flash, FlexApplications are usually broken into logical chunks called “tiers”, where every tier is assigned a roleDesktop-like apps in the web browser

How everything works?

Client / Server modelClient – software which makes requestServer – response to requests

The Servers>As hardware>As software

The primary function of a web server is to store, process and deliver web pages to clients.

Who are the clients?

Web browsersA web browser is a software application for retrieving, presenting and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI/URL) and may be a web page, image, video or other piece of content.

Layout enginesDisplays the formatted content on the screenHTML + CSS

>Trident-based - IE, Netscape, Maxthon, etc.>Gecko-based - Firefox, Netscape, SeaMonkey, etc.

>WebKit-based - Chrome, Safari, Maxthon, etc.>Presto-based - Opera

Web communication

Web communicationA user agent, commonly a web browser or web crawler, initiates communication by making a request for a specific resource using HTTP and the server responds with the content of that resource or an error message if unable to do so.

Web service protocolsIn order for computers to communicate with one another, standard methods of information transfer and processing have been devised. These are referred to as "protocols" and some of the more common ones such as TCP, IP, POP, HTTP / HTTPS, and FTP.

Accessing website

Headers

HTTP responses1xx Informational2xx Success3xx Redirection4xx Client Error5xx Server Error

Proxy serversA proxy server is a dedicated computer or a software system running on a computer that acts as an intermediary between an endpoint device, such as a computer, and another server from which a user or client is requesting a service.

An advantage of a proxy server is that its cache can serve all users. 

Forward proxySend the requests of a client onward to a web server. Users access forward proxies by directly surfing to a web proxy address or by configuring their Internet settings.

Reverse proxyReverse proxies transparently handle all requests for resources on destination servers without requiring any action on the part of the requester.

CacheA web cache is a mechanism for the temporary storage (caching) of web documents, such as HTML pages andimages, to reduce bandwidth usage,server load, and perceived lag. A web cache stores copies of documents passing through it. When this information is requested again, it is not being loaded from the server again, but from the already stored cache.The cache is especially useful when you have a slow or limited Internet connection.

CookiesIs a small piece of data sent from a website and stored in a user's web browser while the user is browsing that website. Every time the user loads the website, the browser sends the cookie back to the server to notify the website of the user's previous activity. Cookies are designed to be a reliable mechanism for websites to remember stateful information (such as items in a shopping cart) or to record the user's browsing activity (including clicking particular buttons, logging in, or recording which pages were visited by the user as far back as months or years ago).

Cookies>Several Web sites also use cookies for personalization based on users' preferences. For example, the Wikipedia Web site allows authenticated users to decide the skin of pages; the Google search engine allows users (even non-registered ones) to decide how many hits per page they want to see.

Any questions?

Thank you!