Advanced Web 2012 Lecture 2 Sean Costain 2012

How the Web Works - Refresh Sean Costain 2012 The web is a matrix of servers that handle client requests and deliver the content at a per-request action.

Web Content Sean Costain 2012 Web content is data that is delivered to the end user through web pages. Content is now Dynamic, in that it responds to user actions. -Content is normally stored in databases -MySQL, MsSQL -Access of Dynamic content requires advanced languages -PHP, ASP

Web Server Sean Costain 2012 A web server is a computer that runs a special service that is designed to handle web requests. A web request is a data stream that flows on port 80 or port 443. The language of the web is TCP/IP. The main difference between a pc and a server is the amount of requests that the machine can handle, and it’s method of supplying the requested information.

TCP/IP Sean Costain 2012 Transmission Control Protocol (TCP) is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol (IP), and therefore the entire suite is commonly referred to as TCP/IP. TCP provides reliable, ordered delivery of a stream of octets from a program on one computer to another program on another computer. TCP is the protocol used by major Internet applications such as the World Wide Web, , remote administration and file transfer.

Web Server Sean Costain 2012 TCP/IP Ports Port 80 – http traffic; the primary port used by the world wide web (www) system. Web servers open this port then listen for incoming connections from web browsers. Port 443 – https traffic; secure web browser communication. Data transferred across such connections are highly resistant to eavesdropping and interception. Port 80 Port 443 TCP/IP Has 1056 common ports for communication

Web Server Sean Costain Main Web servers in the world Apache IIS (Internet Information Services) Apache is Open Source and can be run on pretty much any operating system. IIS is proprietary and runs only on the Windows operating system. Both servers do pretty much the same thing, handle client requests and deliver content. We’re using Apache (XAMPP) in this course.

Remote Server Sean Costain 2012 A remote web server is a server that is not running on the machine you are currently using. Remote servers are normally production servers, these can come in various formats such as: Dedicated Servers Virtual Servers Shared Web Space Dedicated Server Expensive Full Control All the hardware is for your use only. Virtual Server Medium Price Full Control over VM, not physical config Other user share the same hardware Shared Web Cheap Control only over your data. All resources shared with other clients, physical and digital.

Local Server Sean Costain 2012 A local web server is a server that is running on the machine you are currently using. Local servers are normally development servers, these can come in various formats such as: A server your company controls A desktop machine you use Portable on a USB Local servers are faster than remote servers as the browser request doesn’t have to leave the machine.

Communication Methods Sean Costain 2012 When it comes to Remote servers, there are a few ways of communicating with the server. This is all dependent on the type of server. Dedicated server : RDP (port 3389), Telnet (port 23), SSH (port 22), FTP (port 21), File upload through the web (port 80) All other server types: FTP (port 21), File upload through the web (port 80) RDP, telnet and SSH all allow for access to manipulate the operating system. FTP and file upload, only manipulate your web files RDP FTP

Communication Methods Sean Costain 2012 Local servers, on the other hand, are extremely easy to work with. You can just copy over the working files or work directly on them with your web application. Apache stores it’s web pages in a folder called htdocs. IIS stores it’s web pages in a folder called wwwroot

Sean Costain 2012