What is TCP / IP
Both are protocols that govern how information is sent from computer to computer
- IP is a core protocol and a format for information in transit (IP packet)
- TCP (Transmission Control Protocol) uses IP to provide a reliable mechanism to send sequences of bytes from source to destination
very general, how does information travel through the internet
Data chunks called ‘packets’ travel from host to host through networks of nodes and may take different routes
3 characteristics of IP addresses
- must have a name (e.g. ucl.ac.uk)
- a Domain Name Service (DNS) converts names to addresses
- Domain Name Registration: http://www.internic.net/
what is the World Wide Web Consortium (W3C)
an international community that develops open standards to ensure the long-term growth of the Web
difference between HTTP and HTML
HTTP: the foundation of data communication (HyperText Transfer Protocol)
HTML: format or presentation of information returned by the server (HyperText Markup language)
what is an URL
specifies a name for online document and where to find it (Uniform Resource Locator)
Each website, and each page or bit of information on that site, has a URL
4 characteristics of browsers
- runs on client computer
- connected to web servers
- uses URLs & HTTP to request documents from web servers
- formats and displays those HTML documents
difference between websites and webpages
A Website is a collection of web pages that:
- Reside at a single network location
- Are interlinked
- Following a sequence of links
- Generally share design characteristics
A Webpage is a document consisting of one or more web resources which are rendered simultaneously as a single object. Generally marked up in HTML.
characteristics of a web server
a program
- runs on a computer
- replying to browser requests for URL associated content
- browser makes a web connection to a server using HTTP
- manages form input
- link forms and browsers with programs such as databases running on the server
Flash vs HTML5
Adobe Flash
• Can show video, display graphics, play games
• Ubiquitous web format
• Easy to create content using Adobe’s tools
But…
- Requires a plug-in, Proprietary format
- Notoriously unstable, Introduced security problems
- Uses up a lot of battery power
- HTML5
- Browser plays audio & video – no plug-in required
- Standards compliant
- Much better mobile coverage than Flash
How is Web Development different in big cooperations?
Many people work on the code, hence they use various collaboration tools and a distributed version control system (e.g. Git);
They use automation servers (e.g. Jenkins) to pull data from a repositories (e.g. Github) and send an image to a registry;
Due to the need for scalability (and the need for more than one server) they do not run VM as they are reasonably inefficient for such tasks — but rather use containers built from images (e.g. using Docker);
To cope with huge demand from all over the world and multiple servers, they will have load-balancers with master/slave servers in a cloud infrastructure (in different regions);
To ensure high level of security they use a combination of passwords and SSL certificates when connecting to servers.
What is a Content Delivery Network (CDN)?
A geographically distributed network of proxy servers and their data centers. The goal is to distribute service spatially relative to end-users to provide high availability and high performance.
For example, if you don’t want to download and host Bootstrap yourself, you can include it from a CDN.
4 important components of the WWW
- HTML
- HTPP
- URL
- Browsers
Difference between the Internet and Web
Internet = an international network of networks and computers, a global information system
The web = an application on the Internet
