Sharing Knowledge

Umbrello UML Modeler

2011-02-19T04:30:00.000-08:00

Introduction:

Umbrello UML Modeler is a free software UML diagram application available natively for Open Source Operating System(linux). It is a part of the KDE Desktop Environment but works well with other desktops and programming environments.
UML defines diagrams that can describe nearly every aspect of software, from class structures to individual procedural activities to collaboration amongst classes, and even how software eventually is to be deployed.
We will explore the features of the most popular UML editors, looking at four important factors: user interface look and feel, support for code generation and code import, conformance with the latest UML standard, and integration with the environment.
It is a free software so it can be freely distributed or modified by anyone who has a copy of it.
Umbrello has Three areas to draw diagrams are Tree view,Work area and Documentation Area.

UML stands for Unified Modeling Language.
Umbrello UML modeler is an Open source tool.
UML Modeler is fully concentrates on designing because with fine designing we canget implemented to successfull software.
It consists of over 65,000 lines of code including comments and is made up of almost 300 files/classes.
It is currently ranked in the top 10% of sourceforge.net projects.
It is hard to judge the number of users but the latest version has had over 10,000 individual downloads and its inclusion into KDE will increase the many users.
Other competitive products of Umbrello are ArgoUML, Dia, Kivio, visio.

Compare Rational Rose and Umbrello:

Rational Rose is very popular UML modeling language for designing diagrams but it is very costly and widely used for closed source system.
We can get only a trial version of the Rational Rose software to work but Umbrello is come with the operating system as open source or we can download it and so we can implement all those diagramming features and code generation of Rational Rose.

Umbrello Features are:

It is implemented with all types of UML diagrams are:

Class Diagram
UseCase Diagram
Sequence Diagram and Collaboration Diagram
State and Activity Diagram
Component and Deployment Diagram

It has reverse engineer code and it is exported to a large range of languages such as

C++, Java
Javascript, Actionscript
Perl, PHP
Python

UML is used for:

Planning Requirements
Plan class structure
Share plans with others

Advantages:

It is standard language and it is based on industry standards.
It is a free software, user friendly and easy to understood.
It helps people new to the code base become familiar to generate the code base.
The information should not be lost even power off or restarted or shut down the system,when you open your umbrello uml modeler it shows the already designed diagrams.
The diagrams we have designed should be automatically saved as autosave.xmi which is not available in other UML tools like Rational Rose,Argo UML.
File format (loosley) based on XMI, an XML language for UML.
Software Developers can easily design and document everywhere using UML.
The latest version of Umbrello UML modeler 2.0.0 is available with 2.30mb.
We can create code directly which enhances productivity and saves a lot of the developer's time.

Features of Linux OS

2010-12-24T03:47:00.000-08:00

LINUX:

Linux Kernel or Linux is an operating system kernel used by a family of Unix-like operating systems.
Linux distribution is used to refer to various operating systems built on top of Linux Kernel.
The Linux kernel is released under the GNU General Public License version 2 (GPLv2) and developed by contributors worldwide.
Linux is one of the most prominent examples of Free / Open Source software.

How Linux Load while switch on the system:

System on
|
BIOS(Boot Strap)
|
Boot Loader(Grub)
|
O/S Operates

|
I/O & Other peripherals

Difference Between Closed and Open Source Softwares:

Linux Operating System Parts :

Kernal
Shell
File Structure
Utilities

1. Kernel:

Kernel is Central component of computer operating systems (OS).
Its responsibilities include managing system's resources (communication between hardware and software components).
Kernel -->Monolithic in Linux--> Core part of OS. It controls all part such as H/W and S/W.

Monolithic:

Heavily loaded to control all operations
Complex and difficult to maintain.

Micro Kernel:

Micro Kernel has only basic functionalities
Additional components will handle remaining tools.
Easy to maintain

2. Shell:

A shell is a Command Interpreter and it provides an interface for user. It receives ommand from user, then interprets and sends commands to kernal for execution.

3. File Structure:

In Linux file structure files are grouped according to purpose.
For ex: commands, data files, documentation.
This file structure organizes way of files are stored in a storage device such as disks and printers.
All directories are grouped under root entry " / ".

The Directories under Root are listed below:

root -- The home directory for the root user
home -- Contains the user's home directories along with directories for services

FTP
HTTP
Samba
George

bin -- Commands needed during bootup that might be needed by normal users. Almost all user commands are in /bin or /usr/local/bin.
sbin -- Like bin but commands are not intended for normal users. Commands run by LINUX.
proc -- This filesystem is not on a disk. It is a virtual filesystem that exists in the kernels imagination which is memory. A directory with info about process number . Each process has a directory below proc.
usr -- Contains all commands, libraries, man pages, games and static files for normal operation.
include -- Header files for the C programming language. Should be below /user/lib for consistency.
lib -- Shared libraries needed by the programs on the root filesystem. Unchanging data files for programs and subsystems.
X11R6 -- The X windows system files. There is a directory similar to usr below this directory.
X386 -- Like X11R6 but for X11 release 5
boot -- Files used by the bootstrap loader, LILO. Kernel images are often kept here.
modules -- Loadable kernel modules, especially those needed to boot the system after disasters.
man -- Manual pages
info -- Info documents
doc -- Documentation
dev -- Device files
etc -- Configuration files specific to the machine.
skel -- When a home directory is created it is initialized with files from this directory
sysconfig -- Files that configure the linux system for devices.
var -- Contains files that change for mail, news, printers log files, man pages, temp files
file
local -- The place for locally installed software and other files or Variable data for programs installed in /usr/local.
lock -- Lock files. Used by a program to indicate it is using a particular device or file
log -- Log files from programs such as login and syslog which logs all logins and logouts.
run -- Files that contain information about the system that is valid until the system is next booted
spool -- Directories for mail, printer spools, news and other spooled work.
tmp -- Temporary files. Programs running after bootup should use /var/tmp.
catman -- A cache for man pages that are formatted on demand
mnt -- Mount points for temporary mounts by the system administrator.

4. Utilities:

These are specialized programs such as editors, compilers, and communication programs that performs standard computing operations.

PostgreSQL Connection with PHP

2010-12-23T06:56:00.000-08:00

How to connect PostgreSQL with PHP:

All of the standard PostgreSQL connection parameters are available in the connection string. The most commonly used options and their meanings are listed below:

* Dbname: Database to connect to (Default: $PGDATABASE)

* User: User name to use when connecting (Default: $PGUSER)

* password: Password for the specified user (Default: $PGPASSWORD or none)

* Host: Name of the server to connect to (Default: $PGHOST or localhost)

* hostaddr: IP address of the server to connect to (Default: $PGHOSTADDR)

* Port: TCP/IP port to connect to on the server (Default: $PGPORT or 5432)

$db_handle1 = pg_connect("dbname=database1");

$db_handle2 = pg_connect("dbname=database2");

PHP provides a number of simple functions for retrieving information on the current database connection based on the connection handle provided. Such functions include:

* pg_dbname() -- Returns the name of the current database

* pg_host() -- Returns the hostname associated with the current connection

* pg_options() -- Returns the options associated with the current connection

* pg_port() -- Returns the port number of the current connection

* pg_tty() -- Returns the TTY name associated with the current connection

PostgreSQL Functions to retrieve information from Database:

1. pg_fetch_all: