WebEngineering

Web engineering is the software development of web applications, web services or other complex websites such as portal systems, shopping sites. As a rule, web engineering is also the further development and expansion of previously created websites.
Web-Engineering transfers the methods of software engineering to the development of web applications and extends over the entire lifecycle of a web application. Standardized engineering processes are developed which take into account the differences to classical software technology. Web frameworks are used for this.

The World Wide Web (WWW). It is an information space in which the items of interest, referred to as resources, are identified by global identifiers called Uniform Resource Identifiers (URI). Core specifications for web technologies:

• Uniform Resource Locator (URL)
• Hypertext Transfer Protocol (HTTP)
• Hypertext Markup Language (HTML)

HTTP is the most important service on the internet.

A client initiates a connection to a server with a request. This is sent via HTTP to a server. The server provides the resources. After that request, the server sends a response to the client. This response is in form of data, images, videos, music respectively.
In real world: the client connects to the server using TCP/IP protocol. The client sends then a request via HTTP to the server, e.g. in form of an URL. The server prepares the response, establishes the connection again and sends the response.
A request contains a method – the mostly used ones are GET and POST, where GET tells the server to send data and POST tells the server to store data in a database for example – a URL, the header that includes the host-server to which we are sending the request, the type of file that is accepted (“text/html”, “image”, etc.), the language accepted etc., as well as the body which contains data.
A response message contains the status code which tells the client whether the request succeeded or failed or whatever, e.g. the famous 404: file not found. Furthermore, it contains the header which provides a lot of data, e.g. the date, content-language etc. Finally, there’s the body that contains the data itself.

Static HTML websites are provided from the server. They are static, meaning that there is no dynamic content that changes. Static webpages are not very often found anymore these days. However, most of the websites accessed in the “darknet” via TOR-Browser still are static, due to security and speed.
Dynamic websites on the other hand contain information that changes, depending on the viewer, the time of the day, the time zone, the viewer's native language, and other factors.

In contrast to static Web pages, the content in dynamic web pages will be generated instantly when the user requests it. Examples: daily weather reports, stock quotes, vacant seats on flights, answers to queries to search engines, directories, catalogues. The Web server executes a program that fetches the requested data from databases (database server) and generates an HTML file. Finally, the web server sends the HTML data to the Web browser.

• Library A library is simply a collection of functions wrapped up into a package that can be imported into a code project and re-used. (e.g. JQuery)

• Framework Frame Work is a formatted structure, which may have both your code and library file. this describes a given structure of "how" you should present your code. (e.g. Laravel, Angular)

The key difference between a library and a framework is the “Inversion of Control”. When you call a method from a library, you are in control. But with a framework, the control is inverted; the framework calls you. The framework is more about the structure. Frameworks control the flow of your applications, libraries do not.

The CI (corporate identity) must often be considered. The marketing provides the guidelines, images, color schemes or logos for this process. However, the topic of images and logos is an aspect of web design that should not be underestimated. Images and logos can be provided in a wide variety of formats, sizes, or dimensions. In the web area, especially JPG, PNG, or SVG are used. Color schemes are usually implemented using CSS. Also, fonts should be selected carefully since this contributes to the website’s 1^st impression, furthermore, a convenient font makes it easier to read a text.
A design of a website is also often responsive. This means, that a website adapts to different devices and screen sizes. In the past, web designers were developing different layouts for different screen sizes. Nowadays, this goes a lot easier. Responsive websites are often realized by a template or a CSS framework such as Bootstrap.
Wireframing is a term used in web-design. Wireframes are simplistic drafts of how a website should look like. Based on the wireframes, the prototype is developed which actually resembles the final website.

Predefined (or standard library) functions are those functions which are already defined like the println() and the random(), whereas the userdefined functions are the functions those are created individually by the programmer in the program and will be called later and used. PHP has more than 1000 built-in functions.

Every function has a name including parameters in brackets. Important: Function names are NOT case-sensitive.

Consider, that local variables inside a function are only known in that specific context (context dependent).

• Local variables: only available inside a function.
• Global variables: instantiated outside of a function.
• Super-global variables: usually system variables, which are globally available.