Web Services

Web Site:

A website, also written as Web Site,  web site, or simply site,  is a set of related web ages containing content (media), including text, video, music, audio, images, etc. A website is hosted on at least one web server, accessible via a network such as the Internet or a privatelocal area network through an Internet address known as a Uniform Resource Locator. All publicly accessible websites collectively constitute the World Wide Web.

A web page is a document, typically written in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). A web page may incorporate elements from other websites with suitable markup anchors.

Web pages are accessed and transported with the Hypertext Transfer Protocol (HTTP), which may optionally employ encryption (HTTP Secure, HTTPS) to provide security and privacy for the user of the web page content. The user's application, often a web browser, renders the page content according to its HTML markup instructions onto a display terminal.

The pages of a website can usually be accessed from a simple Uniform Resource Locator (URL) called the homepage. The URLs of the pages organize them into a hierarchy, althoughhyperlinking between them conveys the reader's perceived site structure and guides the reader's navigation of the site.

Overview:

A website is hosted on a computer system known as a web server, also called an HTTP server, and these terms can also refer to the software that runs on these systems and that retrieves and delivers the web pages in response to requests from the website users. Apache is the most commonly used web server software.

Software Systems:

1. Servlet:  A servlet is a “Java programming language class” used to extend the capabilities of servers that host applications accessed via request programming model. Although servlets can respond to any type of request, they are commonly used to extend the applications hosted by Web servers. Thus, it can be thought of as a Java Applet that runs on a server instead of a browser.  

2. JSP: JavaServer Pages (JSP) is a Java technology that helps software developers serve dynamically generated web pages based on HTML,XML, or other document types.

3. PHP: (hypertext preprocessor) PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into a HTML source document and interpreted by a web server with a PHP processor module which generates the resulting web page.

4. ASP.NET (Active Server Pages) ASP.NET is a Web application framework developed and marketed by Microsoft to allow programmers to build dynamic Web sites, Web applications and Web services.

Plug ins are available to expand the features and abilities of web browsers to show active content or even create rich internet applications. Examples of such plug-ins are Microsoft Silverlight, Adobe Flash, Adobe Shockwave or applets written in Java. Dynamic HTML also provides for user interactivity and realtime element updating within web pages (i.e., pages don't have to be loaded or reloaded to effect any changes), mainly using the Document Object Model (DOM) and JavaScript, support which is built-in to most modern web browsers.

Colour, typography and interaction:

 Cascading Style Sheet(CSS)

Browsers:

It can have a graphical user interface.

Web Service: (REST API : - Representational State Transfer)

Web Services can convert your applications into Web-applications.

Web Services are published, found, and used through the Web.

A Web service is a method of communication between two electronic devices over the web.

Basic platform of web service:

· HTML

· XML

What are web services?

· Web services are application components

· Web services communicate using open protocols

· Web services are self-contained and self-describing

· Web services can be discovered using UDDI

· Web services can be used by other applications

· XML is the basis for Web services

How does it Work?

The basic Web services platform is XML + HTTP.

XML provides a language which can be used between different platforms and programming languages and still express complex messages and functions.

The HTTP protocol is the most used Internet protocol.

Web services platform elements:

· SOAP (Simple Object Access Protocol)

· UDDI (Universal Description, Discovery and Integration)

· WSDL (Web Services Description Language)

· REST api (Representational State Transfer)

We will explain these topics later in the tutorial.

Web Architecture

Web Services Architecture