Hotel Management System SW and HW requirements.

SOFTWARE & HARDWARE REQUIREMENTS

Client Server

Over view:

With the varied topic in existence in the fields of computers, Client Server is one, which has generated more heat than light, and also more hype than reality. This technology has acquired a certain critical mass attention with its dedication conferences and magazines. Major computer vendors such as IBM and DEC; have declared that Client Servers is their main future market. A survey of DBMS magazine reveled that 76% of its readers were actively looking at the client server solution. The growth in the client server development tools from $200 million in 1992 to more than $1.2 billion in 1996.

Client server implementations are complex but the underlying concept is simple and powerful. A client is an application running with local resources but able to request the database and relate the services from separate remote server. The software mediating this client server interaction is often referred to as MIDDLEWARE.

The typical client either a PC or a Work Station connected through a network to a more powerful PC, Workstation, Midrange or Main Frames server usually capable of handling request from more than one client. However, with some configuration server may also act as client. A server may need to access other server in order to process the original client request.

The key client server idea is that client as user is essentially insulated from the physical location and formats of the data needs for their application. With the proper middleware, a client input from or report can transparently access and manipulate both local database on the client machine and remote databases on one or more servers. An added bonus is the client server opens the door to multi-vendor database access indulging heterogeneous table joins.

What is a Client Server

Two prominent systems in existence are client server and file server systems. It is essential to distinguish between client servers and file server systems. Both provide shared network access to data but the comparison dens there! The file server simply provides a remote disk drive that can be accessed by LAN applications on a file-by-file basis. The client server offers full relational database services such as SQL-Access, Record modifying, Insert, Delete with full relational integrity backup/ restore performance for high volume of transactions, etc. the client server middleware provides a flexible interface between client and server, who does what, when and to whom.

Why Client Server

Client server has evolved to solve a problem that has been around since the earliest days of computing: how best to distribute your computing, data generation and data storage resources in order to obtain efficient, cost effective departmental an enterprise wide data processing. During mainframe era choices were quite limited. A central machine housed both the CPU and DATA (cards, tapes, drums and later disks). Access to these resources was initially confined to batched runs that produced departmental reports at the appropriate intervals. A strong central information service department ruled the corporation. The role of the rest of the corporation limited to requesting new or more frequent reports and to provide hand written forms from which the central data banks were created and updated. The earliest client server solutions therefore could best be characterized as “SLAVE-MASTER”.

Time-sharing changed the picture. Remote terminal could view and even change the central data, subject to access permissions. And, as the central data banks evolved in to sophisticated relational database with non-programmer query languages, online users could formulate adhoc queries and produce local reports with out adding to the MIS applications software backlog. However remote access was through dumb terminals, and the client server remained subordinate to the Slave\Master.

Front end or User Interface Design

The entire user interface is planned to be developed in browser specific environment with a touch of Intranet-Based Architecture for achieving the Distributed Concept.

The browser specific components are designed by using the HTML standards, and the dynamism of the designed by concentrating on the constructs of the Java Server Pages.

Communication or Database Connectivity Tier

The Communication architecture is designed by concentrating on the Standards of Servlets and Enterprise Java Beans. The database connectivity is established by using the Java Data Base Connectivity.

The standards of three-tire architecture are given major concentration to keep the standards of higher cohesion and limited coupling for effectiveness of the operations.

Features of The Language Used

In my project, I have chosen JAVA for developing the code.

About JAVA

Introduction

The Java programming language and environment is designed to solve a number of problems in modern programming practice. Java started as a part of a larger project to develop advanced software for consumer electronics. These devices are small, reliable, portable, distributed, real-time embedded systems. When we started the project we intended to use C++, but encountered a number of problems. Initially these were just compiler technology problems, but as time passed more problems emerged that were best solved by changing the language.

Java

A simple, object-oriented, network-savvy, interpreted, robust, secure, architecture neutral, portable, high-performance, multithreaded, dynamic language.

One way to characterize a system is with a set of buzzwords. We use a standard set of them in describing Java. Here's an explanation of what we mean by those buzzwords and the problems we were trying to solve.

Archimedes Inc. is a fictitious software company that produces software to teach about basic physics. This software is designed to interact with the user, providing not only text and illustrations in the manner of a traditional textbook, but also a set of software lab benches on which experiments can be set up and their behavior simulated. The most basic experiment allows students to put together levers and pulleys and see how they act. The italicized narrative of the trials and tribulations of the Archimedes' designers is used here to provide examples of Java language concepts.

Simple

We wanted to build a systsem that could be programmed easily without a lot of esoteric training and which leveraged today's standard practice. Most programmers working these days use C, and most programmers doing object-oriented programming use C++. So even though we found that C++ was unsuitable, we designed Java as closely to C++ as possible in order to make the system more comprehensible.

Java omits many rarely used, poorly understood, confusing features of C++ that in our experience bring more grief than benefit. These omitted features primarily consist of operator overloading (although the Java language does have method overloading), multiple inheritance, and extensive automatic coercions.

We added automatic garbage collection, thereby simplifying the task of Java programming but making the system somewhat more complicated. A common source of complexity in many C and C++ applications is storage management: the allocation and freeing of memory. By virtue of having automatic garbage collection (periodic freeing of memory not being referenced) the Java language not only makes the programming task easier, it also dramatically cuts down on bugs.

The folks at Archimedes wanted to spend their time thinking about levers and pulleys, but instead spent a lot of time on mundane programming tasks. Their central expertise was teaching, not programming. One of the most complicated of these programming tasks was figuring out where memory was being wasted across their 20K lines of code.

Another aspect of being simple is being small. One of the goals of Java is to enable the construction of software that can run stand-alone in small machines. The Java interpreter and standard libraries have a small footprint. A small size is important for use in embedded systems and so Java can be easily downloaded over the net.

Object-Oriented

This is, unfortunately, one of the most overused buzzwords in the industry. But object-oriented design is very powerful because it facilitates the clean definition of interfaces and makes it possible to provide reusable "software ICs."

Simply stated, object-oriented design is a technique that focuses design on the data (=objects) and on the interfaces to it. To make an analogy with carpentry, an "object-oriented" carpenter would be mostly concerned with the chair he was building, and secondarily with the tools used to make it; a "non-object-oriented" carpenter would think primarily of his tools. Object-oriented design is also the mechanism for defining how modules "plug and play."

The object-oriented facilities of Java are essentially those of C++, with extensions from Objective C for more dynamic method resolution.

The folks at Archimedes had lots of things in their simulation, among them ropes and elastic bands. In their initial C version of the product, they ended up with a pretty big system because they had to write separate software for describing ropes versus elastic bands. When they rewrote their application in an object-oriented style, they found they could define one basic object that represented the common aspects of ropes and elastic bands, and then ropes and elastic bands were defined as variations (subclasses) of the basic type. When it came time to add chains, it was a snap because they could build on what had been written before, rather than writing a whole new object simulation.

Multithreaded

There are many things going on at the same time in the world around us. Multithreading is a way of building applications with multiple threads Unfortunately, writing programs that deal with many things happening at once can be much more difficult than writing in the conventional single-threaded C and C++ style.

Java has a sophisticated set of synchronization primitives that are based on the widely used monitor and condition variable paradigm introduced by C.A.R.Hoare. By integrating these concepts into the language (rather than only in classes) they become much easier to use and are more robust. Much of the style of this integration came from Xerox's Cedar/Mesa system.

Other benefits of multithreading are better interactive responsiveness and real-time behavior. This is limited, however, by the underlying platform: stand-alone Java runtime environments have good real-time behavior. Running on top of other systems like Unix, Windows, the Macintosh, or Windows NT limits the real-time responsiveness to that of the underlying system.

Lots of things were going on at once in their simulations. Ropes were being pulled, wheels were turning, levers were rocking, and input from the user was being tracked. Because they had to write all this in a single threaded form, all the things that happen at the same time, even though they had nothing to do with each other, had to be manually intermixed. Using an "event loop" made things a little cleaner, but it was still a mess. The system became fragile and hard to understand. They were pulling in data from all over the net. But originally they were doing it one chunk at a time. This serialized network communication was very slow. When they converted to a multithreaded style, it was trivial to overlap all of their network communication.