SIP PHP Posibilities

8/3/2019 SIP PHP Posibilities

1/35

SIP PHP Posibilities


2/35

Advantages of using PHP ina web project like

SIP (and others) and considerations about

AJAX projects and web projects ingeneral.


3/35

The usual structure ofa PHP web application is a 3

tier one; this means the high level structure of the

SIP application is very similar.


4/35

Data layer

This would be adatabase server; the most

common ones used with PHP are MySql,

Postgres, but any database server can be

used: Oracle, MsSql etc.

If the database server is Mysql then theoperating system is recommended to be Linux,

andnot Windows, since the performance of

Mysql on Linux is significantly better.


5/35

Mysql technical specifications andadvantages

Pluggable Storage-Engine Achitecture (InnoDB , MyISAM, Merge, Memory,Archive)

ANSI SQL (SubQueries, Joins, Cursors; Prepared Statements; Views;

Triggers;Stored Procedures; User-Defined Functions);

ACID Transactions, Commit, Rollback , Foreign Keys, Referential Integrity

Easy Install and Setup;

Built-in Replication Engine, Master/Slave,;

MySQL Cluster (99.999% Availability, Distributed architecture, Synchronous

replication)

99.999% Availability, Distributed architecture, Synchronous replication

Hot Backup for InnoDB, Full, Incremental, Partial Backups, Auto-Restart/Recovery

SSL Support, Built-in Data Encryption/Decryption

Graphical Tools: MySQL Workbench


6/35

MySQL Workbench


7/35


8/35

Business layer

This usually is a web server with support for PHP. The most common

webservers used with PHP are Apache, Lighthttpd, Nginx but also IIS is suported

The Apache webserver has a lot of configuration options and is very well

documentedanddocumentation can be found in many places on the web (by

using Google) .

The Code architecture is recommended to be MVC as it is a flexible and

week coupled . This means, that , if it it is implemented correctly, anddepending on the application, changes can be done inany of the 3 main parts

of MVC, without having to change somethingalso in other part.

There is no conflict between the 3 tier architecture and MVC; The Model is the

MVC component which would contain the the business layer. The View neednot access directly the Model, since it is the Controller which makes the

connection between the Model and the View


9/35

The Presentation (Client) Layer

This would be standard HTML (+CSS, JS,Flash),

generated by PHP . PHP appearedas a web scripting language which can

be integrated into web pages. It has evolved into afull language with strong object oriented capabilities.

At the same time it kept it real ease of use, simplicityand conciseness, so it is recommended that thelanguage used in the presentation pages themselves

should also be PHP.

Alternatives to using PHP in the presentation

layer exist, like Smarty, but they are notrecommended, since you cannot really get morechort and concise than PHP is, andalso for

performance reasons.


10/35

A) classical web application the flow

1. the browser sends an HTTP request to the web server;

2. the server receives the request and sends it to the PHP

component;3. this loads and executes the controller

4. the controller cando:a. security checks (like authenticationandauthorization) ;

b. loads and executes one or more models;

c. the models (which should implement the business logic) accessthe necessary resources (like database, web services, or others),and returndata (or populate some internal Model state);

d. load the View ; the view is composed of HTML ((+CSS, JS,Flash)with place holders for dynamic data, and basic operations over

presentationdata(iterate, conditions);e. render the view by merging the data from the Model with the

View;

f. send the result to the client browser.

5. each time the client clicks ona link the new page is loaded

by going the full process starting from point 1.


11/35

B) A massively AJAX web application (like SIP) flow :

1. the browser sends an HTTP request to the web server;

2. the server receives the request and sends it to the PHP component;

3. this loads and executes the controller

4. the controller cando:a. security checks (like authenticationandauthorization);b. loads and executes a minimum number of models;

c. loads aView which is very basic and is only the skeleton for the full html page; theview contains special javascript which will execute once the browser receives fully thebasic html page;

d. renders andview and sends it to the client

5. The client (browser) receives the basic html page , andafter it is fully loaded itexecutes the javascript set to execute on DOM load.

6. This script makes many AJAX calls to the server for the content of each block inthe page. Each of these requests goes through the full process describedat pointA, but the result is only the content ofa block in the page .

7. the page is now fully loaded in the client browser

8. each time the client clicks ona link one of 2 things can happen:a. if the page which the client wants is different enough then the current page the client

is on, then the whole process from the B 1 starts again;

b. if the page which the client wants is similar enough to the current page the client ison, then process from point 6 executes, but not for all the blocks in page but only forthe blocks which need to be updated (depending on the business logic andapplication) .


12/35

Advantages and disadvantages of a massively AJAX web

applications

Advantages

If the pages do not vary much between them (from

a layout point ofview), then the responsiveness of

the application for the end user is increased.


13/35

Disadvantages

The design has to be made by the designer with great care , to

support missing, appearinganddisappearing blocks from thepage without the layout breaking inany browser;

The pages shouldnot vary much between them because thiswould mean many ajax request to the server, slow load timesfor the pages and losing the AJAX responsiveness advantage .

The caching strategy is more difficult to do, because: data cannot be easily cached for all the blocks necessary in one

page;

blocks can have interdependencies which makes cache harder, andcache expiration, simultaneous for all dependent blocks, a problemto handle;

The framework should be adapted to make the many AJAXrequests lighter from load point ofview; otherwise, a firstloadingaa new page from a massively AJAX site, wouldproduce a load significantly higher thana classical webpage;

the business logic has to be divided in 2 places: on the server

and in the client browser inJavascript.


14/35

Object Relational Mapping (ORM)

An ORM is a framework that allows to avoid the mismatch, thedifference in how they work) between the Relational Model and theObject Model, which are both present in most web applications .

The SIP project uses an ORM framework which is Entity Data Model(EDM) .

In PHP, agood ORM framework is Doctrine (http://www.doctrine-project.org/).

Doctrine 2 is divided into three main packages.

Common DBAL (includes Common)

ORM (includes DBAL+Common)

The Doctrine code base is split in to these packages for a few reasonsand they are to...

...make things more maintainable anddecoupled

...allow you to use the code in Doctrine Common without the ORM orDBAL

...allow you to use the DBAL without the ORM


15/35

Doctrine framework

The Common PackageThe Common package contains highly reusablecomponents that have no dependencies beyondthe package itself (and PHP, of course).

The DBAL Package

The DBAL package contains an enhanceddatabaseabstraction layer on top of. The purpose of thislayer is to provide a single API that bridges mostof the differences between the different RDBMSvendors.


16/35

TheORM Package

The ORM package contains the object-relational mapping toolkit

that provides transparent relational persistence for plain PHPobjects.

Doctrine uses the Data Mapper patternat the heart of thisproject, aiming for a complete separation of the domain/businesslogic from the persistence ina relational database management

system. The benefit of Doctrine for the programmer is the ability tofocus solely on the object-oriented business logic and worry aboutpersistence only as a secondary task. This doesnt mean persistenceis not important to Doctrine 2, however there are considerablebenefits for object-oriented programming if persistence and entitiesare kept perfectly separated.


17/35

Doctrine supports Inheritance Mapping . Anmapped superclass is anabstract or concrete classthat provides persistent entity state and mappinginformation for its subclasses, but which is not itselfan entity. Typically, the purpose of such a mappedsuperclass is to define state and mappinginformation that is common to multiple entityclasses.

Doctrine introduces DQL which is best describedasobject-query-language and is adialect ofOQL andsimilar to HQL or JPQL. It does not know the conceptof columns and tables, but only those of Entity-Classand property. Using Metadata it allows for veryshort distinctive and powerful queries.


18/35

Example:

The following query in standard SQL

SELECT sp.FirstName, sp.LastName, sp.HireDate

FROM SalesPerson sp

INNER JOIN Employee e ON sp.SalesPersonID =e.EmployeeID

INNER JOIN Contact c ON e.EmployeeID = c.ContactID

WHERE e.SalariedFlag = 1

AND e.HireDate >= '2008-01-01'

could be written in DQL like this (consideringall the entity classes andMetadata is defined), if we hada class inheritance and inheritance mapping:

SalesPerson extends Employee andEmployee extends Contact

SELECT sp.FirstName, sp.LastName, sp.HireDate

FROM Contacts\Employees\SalesPerson AS sp

WHERE e.HireDate >= '2008-01-01'


19/35

Debugging

AnAJAXapplication is inherently more difficult to debug,because:

it has business logic in 2 separate places: in the server andin the client browser;

the very flexible and no private members javascriptnature;

However, to debuganAjax application in PHP one ca use:

simple debug logs messages, directly to output or to logfiles;

step by step debugging in PHP, by using the Xdebugextension;

Firebug to debug in the browser Javascript andAjax calls .


20/35

Deployment

The deployment ofa PHP web project is generally a simple thing. Itincludes more steps some of which must be done only first time, andsome of which can be skippeddepending on the project:

Deployment related tasks

One time only deployment tasks

install operating system, for example Linux Ubuntu Server or Redhat; install Apache, Php and Mysql;

this can be done easily in linux using packages which can be installed usingjust one command for each program;

install the necessary extensions for PHP, depending on the project;

this can be done easily in linux using packages which can be installed usingjust one command for each program;

configure virtual host inApache


21/35

Regular deployments tasks

put the code and resources files on the server; this can be done

in more ways; using FTP or SFTP; this is not recommended because of the dificulty totrack changes and the exact version present on production;

using SVN updates; this is the recommendedversion because: easy to track changes;

ability to know what version is in production;

ability to revert to a previous code version easily;

rundatabase updates; this can be done in more ways: manually in the database; not recommended, because it is hard to know

which updates were runand which not

usinganautomated script; we have such anautomated sql deploymentscript which works quite well andallows:

to view the sql queries which need to be run; to logall the updates done to the db

to automatilcally run only the not run updates;

to update the log separately from running the queries, in case of unsinchronisedlog, due to database dumps moving;

copy config files, separate for each application instance; for the RTLINFO older versionapplication we were usinga PHP script

which was doing this inan easy way;


22/35

Tools and features which make PHP developmenteasier

XDEBUGXDEBUG

Xdebug is a PHP extension which allows:

more useful error messages;

step by step debugging, together with Eclipse IDE;

full stack trace log innon error conditions, whichcombined with a few tools to view those logs inagraphical manner (for Linux and Windows), make ituseful for performance tuning;


23/35

PhingPhing

A PHP project build system or build tool basedon Apache Ant.

An easy-to-use and highly flexible build framework.

Simple XML buildfiles

Rich set of provided tasks

Easily extendable via PHP classes

Platform-independent: works on UNIX, Windows, MacOSX

No required external dependencies

Built & optimized for ZendEngine2/PHP5


24/35

JSON handlingJSON handling

To work with JSON in PHP is very easy. Toconvert to from PHP object or array to aJSON

object or array you need just 2 functions:

json_encode andjson_decode .


25/35

Security in PHP web applications

Security in PHP web applications does not really depend on theprogramming language. It is a matter of business logic to write secureapplications.

Authentication

Authentication means requestingandverifying the identity of thecurrent user.

Authentication is done usually usinga simple form; the user submits the account details to the server

the server check a persistent storage to see if the account is validand logsin the user;

the fact that the user is logged in is kept in the Session; the session is a

common feature of web applications; it is a storage of small amount ofdata, usually available automatically to any instance of web page for anyuser, logged in or not. The correspondence betweena session on the serveranda user currently browsing the site is done by usinga HTTP cookie whichcontains the session identifier for each user, in his own browser.


26/35

Authorization

Authorization means to check ifa subject has theright to do a certainaction ona certain object.

This can be done in more ways:

Usingaccess lists

Using custom code

generally custom code is the preferred way for very

custom requests of the business logic, anda small

number of operations of objects, in which case the

overhead of usingACLs would be to much;


27/35

Encrypted connections, SSL

Web applications using PHP can use encryptedcommunication between the browser and the

server. This is done by using Public Key

encryptionandCertificates. Protocols: SSL, TLS

The Apache server supports SSL using OPENSSL.

Ingeneral only some parts of the application may

require encrypted communications, like

logging in;

online payments using credit cardand other payment

information.


28/35

Example of the flow a simple request and response

The code examples will be non fully working ones, since we do

not have ready made project where to copy them from and thelack of time to implement an example;

Lets say we need in our applicationa way to present the citiesusing some criteria. This will be a method ofaRESTWebservice; in the PHP applications REST webservices are

much more common than SOAP webservices; also they aremuch more easier to use .

this method will receive parameters using simple HTTP GETand return the informationas aJSON string .

Let us suppose that the application is written inCakePHP .

The AJAX request from the browser would be something like

http://example.com/regions/getCities/parentRegionId:10/minPopulation:5000

Obs: errors are not treated for brevity and clarity;


29/35

CONTROLLER part 1

Ina controller class called regions we will have a public method calledgetCities

public functiongetCities($parentRegionId =null, $minPopulation =null) {

}

this would containamong others The call to the model to get the cities

$cities = $this->City->getCities($parentRegionId,

$minPopulation);

The City property member is automatically instantiated by CakePhpaccording to a list of models we need for each controller.


30/35

MODEL

In the model class City we would have the method:public functiongetCities($parentRegionId, $minPopulation) {

return $this->find(

'all',

array(

'fields' => array('name, 'population', 'surface_area', 'lat', 'long),

'conditions' => array(

'City.parent_region_id' => $parentRegionId,'City.population >= ' . $minPopulation,

),

'order' => array('City.name ASC'),'recursive' => 0,

'contain' => array('Country')

));

}

This method would returnall the cities from the region with id equal to$parentRegionId and which have a minimum population of $minPopulation;

It will also return informationabout the country the city belongs to.


31/35

CONTROLLER part 2

In the controller we will also have the encoding

of the cities to json string:

$citiesJson = json_encode($cities);

$this->set(citiesJson, $ citiesJson);

This will encode the cities informtaion into a

JSON stringand make it available to the view.


32/35

VIEWVIEW

The view will be a file like cities_list.ctp; it will

display agrid with the cities; in the example

below the grid contains other information, but it

is similar.

We will use a javascript library called ExtJs very

useful to draw controls, which are very flexible;

see mode about it on:http://www.sencha.com/products/extjs/


33/35

View template content

This is what the server sends to the client as reponse to the

request to view a block with AJAX.

The rest of the view logic is inside the javascript file array-

grid.js


34/35

View output


35/35

SIP PHP Posibilities

Documents