Java Training Publications from ITS, Inc.

This chapter includes basic knowledge of architecture, design, and development of web applications with several specific frameworks.

4.1. Web Applications Architecture

4.2 Html, JavaScript, jQuery and AngularJS
HTML 5 - for desktop and mobile devices
JavaScript - dynamic engine of web pages

Web application frameworks - AngularJS - http://www.w3schools.com/angular/

Learn to Build Modern Web Apps with MEAN - MongoDB, ExpressJS, AngilarJS, NodeJS

4.3. JSP and Servlets

4.4. Spring and Data Service Frameworks
http://www.tutorialspoint.com/spring/
https://spring.io/guides

4.5. Web Services

4.6. System Security and Web Services Security

4.7. Web Test

4.8. Web Projects
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I am sure you know that Web is the biggest branch of the Internet tree.
World Wide Web (WWW) is based on a mutual agreement between the major vendors. On one side - server side � the vendors who create server applications called Web servers or application servers. The other side � client side � the vendors who create client applications called Web browsers.

The agreement consists of two parts.
- Hypertext Transfer Protocol (HTTP) instructs vendors to use extra headers over the standard TCP/IP communications. (By the way, what do you remember about the standard TCP/IP structure? And what kind of extra HTTP headers do you remember? And what are their main purpose?)
- Hypertext Markup Language (HTML) instructs vendors how to express visual, sound, and text data on the web pages.

Here is an example of HTTP Request with HTTP headers sent by a browser to a web server, JavaSchool.com.


GET /about/publications.html/ HTTP/1.1

Host: javaschool.com

User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 (.NET CLR 3.5.30729)

Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

Accept-Language: en-us,en;q=0.5

Accept-Encoding: gzip,deflate

Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7

Keep-Alive: 300

Connection: keep-alive

Cookie: JSSESSIONID=bcdajq435r4q7ib3vtdjq120

Pragma: no-cache

Cache-Control: no-cache

Several comments related to this request:

User-Agent is a good indication of the device which sent the request. If the request has been sent by a mobile device, there would be the keyword Mobile.

Was it clear so far? Highlight the text in question Or

Cookie collects all cookies that was previously set to a client device by responses from the same server. There might be several lines of cookies, each with its own name (key) and a corresponding value. This is the way for vendors to collect some basic data about you on your own machine. Cookies size is limited to 4096 bytes. User can disallow storing cookies, but you do not want to do this because big vendors, such as Google, Yahoo, and more rely on cookies.

As you might already understood, cookies are small files that browser can store on a client device. (Yes, cookies can be stored on mobile devices, although more limitations applied there.) Browser does it on the order from a server setCookie under the condition that browser setting allows cookies.

How the response from a server to a browser will look like?


HTTP/1.x 200 OK

Date: Fri, 22 May 2015 10:32:25 MST

Server: Apache Tomcat/7.0.55 (HTTP 1.1. Connector)

Connection: close

Pragma: public

Expires: Fri, 22 May 2015 11:32:25 MST

Cache-Control: max-age=3600, public

Content-Type: text/html; charset=UTF-8

Last-Modified: Fri, 22 May 2015 10:05:45 MST

X-Pingback: http://ITUniversity.us/about/publications.html

Vary: Accept-Encoding, Cookie, User-Agent











 Java Training Publications from ITS, Inc.





Content of the document with HTML 5 tags......

The response also deserves several comments.

HTTP/1.x 200 OK
This line with the code=200 is indication that the web page (target) was successfully found.

The most common error codes are:

HTTP 404 � Page not found
Or
HTTP 503 � Server error, when the target is not permitted for direct public access

Note that after HTTP headers are followed by the web page with HTML tags (keywords).
I believe you have a good idea about HTTP and it is about time to look at the Web Applications from above, from the architecture perspectives.

Then we will come back to the Earth, we will learn HTML 5, which is the latest standard for web pages on desktops and mobile devices.
We will learn Java Script to make our web pages more dynamic.

We plan to learn creating one-page applications with AngularJS, a very popular library, which greatly simplifies creating dynamic web pages.
And we will learn the major frameworks based on Java Servlets and Java Server Pages (JSP). These frameworks will allow you creating complex applications on the server side to collect and process data.

Multiple client devices can benefit from these intelligent applications. We will learn mobile applications later in the next chapter.

GET /about/publications.html/ HTTP/1.1 Host: javaschool.com User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 (.NET CLR 3.5.30729) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: JSSESSIONID=bcdajq435r4q7ib3vtdjq120 Pragma: no-cache Cache-Control: no-cache

HTTP/1.x 200 OK Date: Fri, 22 May 2015 10:32:25 MST Server: Apache Tomcat/7.0.55 (HTTP 1.1. Connector) Connection: close Pragma: public Expires: Fri, 22 May 2015 11:32:25 MST Cache-Control: max-age=3600, public Content-Type: text/html; charset=UTF-8 Last-Modified: Fri, 22 May 2015 10:05:45 MST X-Pingback: http://ITUniversity.us/about/publications.html Vary: Accept-Encoding, Cookie, User-Agent <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title> Java Training Publications from ITS, Inc.</title> </head> <body> Content of the document with HTML 5 tags...... </body> </html>