Online Computer Training

PHP code is interpreted by a web server with a PHP processor module, which generates the resulting web page: PHP commands can be embedded directly into an HTML source document rather than calling an external file to process data. It has also evolved to include a command-line interface capability and can be used in standalone graphical applications.

PHP is free software released under the PHP License, which is incompatible with the GNU General Public License (GPL) due to restrictions on the usage of the term PHP. PHP can be deployed on most web servers and also as a standalone shell on almost every operating system and platform, free of charge.

PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language. PHP is now installed on more than 244 million websites and 2.1 million web servers.

First Java Program: Let us look at a simple code that would print the words   Hello World . public class MyFirstJavaProgram {    /* This is my first java program.      * This will print 'Hello World' as the output     */     public static void main ( String [] args ){        System . out . println ( "Hello World" ); // prints Hello World     } } About Java programs, it is very important to keep in mind the following points. Case Sensitivity -   Java is case sensitive which means identifier   Hello   and   hello   would have different meaning in Java. Class Names -   For all class names the first letter should be in Upper Case.   If several words are used to form a name of the class each inner words first letter should be in Upper Case. Example   class MyFirstJavaClass Method Names -   All method names should start with a Lower Case letter.   If several words

What is Java? Java is: Object Oriented Platform independent: Simple Secure Architectural- neutral Portable Robust Multi-threaded Interpreted High Performance Distributed Dynamic Java Environment Setup: Java SE is freely available from the link   Download Java . So you download a version based on your operating system. You can refer to installation guide for a complete detail. Java Basic Syntax: Object -   Objects have states and behaviors. Example: A dog has states-color, name, breed as well as behaviors -wagging, barking, eating. An object is an instance of a class. Class -   A class can be defined as a template/ blue print that describe the behaviors/states that object of its type support. Methods -   A method is basically a behavior. A class can contain many methods. It is in methods where the logics are written, data is manipulated and all the actions are executed. Instant Variables -   Each obje

Gateway : this device is placed at a network node and interfaces with another network that uses different protocols. It works on  OSI layers 4 to 7 . Router : a specialized network device that determines the next network point to which it can forward a data packet towards the ultimate destination of the packet. Unlike a gateway, it cannot interface different protocols. It works on  OSI layer 3 . Switch : a device that allocates traffic from one network segment to certain lines (intended destination(s)) which connect the segment to another network segment. Unlike a  hub , a switch splits the network traffic and sends it to different destinations rather than to all systems on the network. It works on  OSI layer 2 . Bridge : a device that connects multiple  network segments  along the  data link layer . It works on  OSI layer 2 . Hub : a device that connects multiple Ethernet segments, making them act as a single segment. When using a hub, every attached device shares the same  br

Differentiate between types Frame Relay High performance Physical & Data link levels Designed for ISDN Error correction is for higher levels Connection oriented  PVC's Frame Relay VCis 2x DTE with packet switched network inbetween, eah VC is identified by a Data Link Connection Identifier (DCLI) ISDN - Integrated Services Digital Network Physical, Data Link, Network, Transport Layers set of comms protocols HDLC - ISO standard Data Link Layer, bit based for sync. serial links High Level Data Link control Cisco HDLC Won't communicate with any other vendor's PPP Async or Sync Uses Link Control Protocol to build data link connections Compression CHAP / PAP authentication Uses NCP to support IPX, IP, Appletalk, Decnet etc. Frame Relay Terms CO - Central Office CPE - Customer Premise Equipment DCE DTE - typically routers DLCI demarc - Termination point of service provider's cable PSE - packet switch exchange PVC

OSI 7 layer model Application File, Print, database, apps,web Presentation Encryption, compression, translations, ebdic etc. Session Dialog control - nfs, sql, rpc , Connection establishment, data transfer, connection release Transport End to end connection, Flow control, Data integrity, Retransmissions Segments re-ordered before delivery, Make / tear down virtual circuits Network Routing , Map of network (logical) Data Link Framing Ensures messages delivered to correct device MAC - Media Access Control Framing with header & trailer.  contains MAC address of source & destination Media Access - method of communicating with Physical medium Logical Topology - eg Star shaped "ring" in TR error detection LLC - Logical Link Control Optional Flow control with stop/start codes error correction Destination Service Access Point (DSAP) and Source SAP allow upper-layers to work over different LANs by providing comms between Netw