1. PHP Module 1 Hussain Fakhruddin [email_address]

2. Agenda

HTML/XHTML and HTTP Basics Review

PHP and the Web Server Architecture Model

Overview of PHP Capabilities

CGI vs. Shared Object Model

3. HTML/XHTML and HTTP Basics Review

HTML/XHTML a language that every browser knows.

HTTP a protocol that every machine uses to talk with others.

4. HTML Hyper Text Markup Language

Basically designed and used as a common language to retrieve documents from web.

More features (called as tags) added later.

Now is replaced by dynamic languages (like PHP) in some places.

Tags are basically used to organize contents of document.

5. XHTML eXtended HTML

A strict format of HTML

Each starting tag must have ending tag.

There are strict rules to be followed.

e.g. In HTML
is allowed, but in XHTML it must be
Similarly: HTML XHTML

...

......

6. Web Server Architecture Model

Client server model.

Like a query session after a lecture!

Clients send request, server sends reply to the requested.

Our web browser is typical client, which formats HTTP (or HTTPS etc.) request and sends to a server.

A server (e.g. Apache onwww.sachinism.com ) formats response and sends back to the browser.

7. Working of Internet 8. A representation of client-server talk - 1 Client Server To Server, Can you please give me index.htm? 9. A representation of client-server talk - 2 Client Server To Client, Sure, here it is... Contents of index.htm 10. A representation of client-server talk - 3 Client Server Wow... I am lucky to get index.htm so fast! Actual webpage,that can be displayed on browser 11. HTTP HyperText Transfer Protocol

Protocol for talks between Client and server for Websites.

Default Port no. 80

Simple, text based protocol

Request Reply model

Stateless

Two most frequently used methods (operations) GET and POST

12. HTTP Format

Request Format

• Request line (e.g. GET /images/logo.gif HTTP/1.1)

• Headers (e.g. Accept-Language: en)

• An optional message body

13. HTTP Request in details

Request method e.g. GET / POST / PUT

URL where to send the request

HTTP version e.g. 1.1

POST /my_dir/my_sub_dir/my_file.htm HTTP/1.1

14. Request methods -1

HEAD Request only headers for an GET request, not actual resource / data. Used to retrieve meta-data.

GET Request actual resource. Used as a method to send data along with request. This data is shown on address bar of a browser!

POST Request actual resource. Most common method used to send data to be processed by the resource. This data is not shown in address bar, is inserted in request body.

15. Request methods -2

PUT Uploads a resource.

DELETE Removes / Delets a specified resource.

TRACE Redisplays a request, to check if some server in midway to the destination has changed any value.

OPTIONS Returns methods supported by the server's specific resource. Used to check server's functionality / support.

CONNECT Converts the request connection to a transparent TCP/IP tunnel. Not much secure.

16. HTTP Format

Response form

• Status line

• Headers

• An optional message body

17. HTTP Response Status Line

HTTP Version

Status code of 3 digits

Status description

18. HTTP Response Status details

200 OK Request successful

302 Moved Permanently URL is no longer used by server

404 Page not found Requested document / resource not found

500 Internal server error Some error on server

19. Request / Response Headers

Exchange of information between client and server.

Each line : Header name + value

Classification of header lines:

• General header

• Request header

• Response header

• Entity header

20. General Header

Can be present in both request and response.

Header Description

• Cache-control Information about caching

• Connection Connection should be either closed or keptopen.

• Date Current date

21. Request Header

Specific to request messages.

Header Description

• Accept Message format that is supported byclient

• Accept-language Language that client accept

• Host Host and port number of client

• If-modified-since Send the document if newer thanspecified date

• If-unmodified-since Send the document if older thanspecified date

22. Response Header

Specific to response message

Header Description

• Age Age of document

• Retry-after Date after which server is available

• Sever Sever name + port

23. Entity Header

Mostly used in response message

Header Description

• Content-encoding Encoding scheme

• Content-language Language

• Content-length Length

• Last-modified Last modification date and time

• Content-type Type of media document

24. HTTP Example

Request GET http://www.sachinism.com/index.htm HTTP/1.0 Accept: text/html Accept: image/jpeg

Response HTTP/1.0 200 OK Date: Thu, 20-Feb-08 09.00.00 GMT Server: Challenger MIME-version: 1.0 Content-length: 2048 >

25. A representation of client-server talk - 1

• Request GET http://www.sachinism.com/index.htm HTTP/1.0 Accept: text/html Accept: image/jpeg

Client Server To Server, Can you please give me index.htm? 26. A representation of client-server talk - 2

• Response HTTP/1.0 200 OK Date: Thu, 20-Feb-08 09.00.00 GMT Server: Challenger MIME-version: 1.0 Content-length: 2048

Client Server To Client, Sure, here it is... Contents of index.htm 27. A representation of client-server talk - 3 Client Server Wow... I am lucky to get index.htm so fast! Actual webpage,that can be displayed on browser 28. CGI - The Common Gateway Interface

CGI is a standard protocol for interfacing external application software with an information server, commonly a web server.

an information server responds to requests(in the case of web servers, requests from client web browsers)

Each time a request is received, the server analyzes what the request asks for, and returns the appropriate output.

29. 30. CGI

The two simplest ways, for the server, of doing this are the following:

1) If the request identifies a file stored on disk, return the contents of that file;

2) If the request identifies an executable command and possibly arguments, run the command and return its output

31. 32. PHP

PHP Hyper Processor or Personal Hypertext Processor

A server side programming language

Emerged as leading language in server side application development since a decade!

HTML can simply display data (static) whereas PHP can be executed on server and the result is displayed on client (Dynamic)- will discuss later in this session

33. Why use PHP?

1)PHP is a server-side interpreter which is Open Source and free;

2)So is a growing number of PHP web applications;

3)PHP provides familiar syntax to C, Perl and Java developers;

4)PHP has fast connections to popular databases;

5)PHP has fast native connections to the Open Source MySQL database;

34. Why use PHP?

6)PHP runs reliably on Windows, Linux and Mac servers and clients;

7)PHP web pages run reliably on all the popular browsers;

8)PHP's associative arrays are very useful for UI and database apps;

9)PHP's object oriented classes are easy to understand;

10)PHP has been very promiscuous-linking to PDF, SWF, XML, Java, etc, etc.

35. Role of PHP - advantage

Everything goes personalize I.E. User settings, look and feel, some private data etc.

Provides user interactivity

Allows to create own web applications that can be executed remotely!

Examples : any website provides login and thereafter services, live cricket scores on sachinism.com

36. HTML/JSVS PHP

JavaScript = ClientSide; PHP = ServerSide

With php you can have the remote time, with js you can have user time...

with php the source is not lookable in the source code with js the source can be see in the source code of the page.

Javascript NOT EQUAL TO PHP

37. Recap 38. Summary

Internet era began with static webpages written in HTML, which required strict rules created XHTML.

Every web based application (essentially webpages / websites) are communicating on HTTP which follow specific format.

User requests something to server and server sends back relevant data implements client server architecture.

Later on, server side programming languages like PHP adds user interactivity, personalisation of websites.

39. Whats next?

Starting up with PHP

• Obtaining, Installing and Configuring PHP

• Obtaining PHP Source Code

• Installing PHP from Binary Packages

• Dynamic Extensions, Checking Install withphpinfo() Function.