BIS07 Application Development - I

Business Information Systems Application Development An outline of computer programming Prithwis Mukerjee, Ph.D.

What shall we cover here Languages and Environments Computer Languages Development Environments Activities What are the steps required to create an application World of Objects What and why ? Business application design Software development life cycle Water fall method Iterative Method Rational Unified Process

From Desire to Deployment I want the computer to print out “Hello Praxis” on the screen Computer Prints out “Hello Praxis” Hello Praxis Say “ Hello Praxis”

Structure of an “application” Database Application

What does an “application” do ? Database Read Write Print “Process” Data Manipulate Modify Data

Same Task : Two Languages PRINT "Hello World" InputString$ = INLINE$("What is your name > \n") InputString$ = InputString$ + " Welcome to Programming" PRINT InputString$ cout << "Hello World" << endl; cout << "What is your name ?" << endl; gets(InputString); strcat(InputString," Welcome to Programming"); cout << InputString << endl;

What is a computer PROGRAM A set of instructions that A computer can “understand” Correct syntax That [ unless specified otherwise ] are executed sequentially To generate a “desired” result Correct semantics PRINT "Hello World" InputString$ = INLINE$("What is your name > \n") InputString$ = InputString$ + " Welcome to Programming" PRINT InputString$ Exceptions CONDITIONALS LOOPS

Conditional : IF – THEN – ELSE

BOTH : Conditional AND Loop FOR K = 1 TO 10 IF ( K < 5 ) THEN PRINT "I will not be naughty" K ELSE PRINT " I will not be naughty ... but i am getting tired " K END IF NEXT K

The Four Primary Tasks Input – Output Read and Write data From Users From databases Manipulate Data Assign values Perform calculations or “operations” Conditionals IF – THEN – ELSE Change the order of statements depending on certain conditions LOOP Repeat a statement a number of times using some CONDITIONAL statement

Compilation Process Human being “write” a program in HIGH LEVEL LANGUAGE C, C++, Basic “closer” to natural languages like ENGLISH Computers understand only a LOW LEVEL LANGUAGE Which consists of sequences of ZERO and ONE ONLY “Impossible” for a human being to write this code Compilation is a process of converting the HLL to LLL This is a tedious process which is best done by another program called a 'compiler'

Seven Steps to meeting expectations A computer understands instructions given as binary code. A human can delivery instructions in an English like language These are the seven steps required to convert human instructions delivered in English to binary instructions that a computer can understand

Human to High Level Language Choose a language to write the program C, C++, Java VB Script, Javascript Programmer's task is to convert From English Say “hello praxis” To C++ : cout << “hello praxis” Use an “Editor” to write the program in the language of your choice Notepad ? editor Say “ Hello Praxis”

High Level to Low Level Language Same language, say C++, can be compiled by compilers from different vendors Turbo C++ Microsoft C++ UDD C++ HLL like C++ is converted to a low level language which consists of binary code 0 and 1 The Compiler is a piece of software that automates this process Compiler will also locate all syntax errors Spelling Punctuation etc editor compiler

Link with pre-built parts Linker will also spot errors like undefined external requests Not all the instructions needed for the complete execution are written by the programmer Many parts of the program are provided by the vendor who has supplied the compiler in low level machine language These have to be linked together with the part of the program written by the programmer editor compiler linker

First Execution The binary machine code is now ready for execution on the operating system Windows XP / Vista Unix / Linux The first execution is expected to show up non-syntax errors : Errors in logic Errors in specifications editor compiler linker runtime

Debugging : Locating & Fixing Errors The debugging process generally leads all the way back to the editor where the program is altered to fix the problem. All subsequent steps are done again Until no more errors are found. editor compiler linker runtime debugger

Deployed for Use The final program is distributed on CDs or as downloads on the internet Has to be packaged in an appropriate manner With necessary runtime libraries Pricing Decisions Freeware ? Single user license ? Multiuser license ? Hello Praxis editor compiler linker runtime debugger packaging

Integrated Development Environment A single piece of software that does all the six functions IDE is different from a language For the same language there are different IDEs from different vendors Some IDEs are better or more user friendly Some IDEs are free, others have to bought I ntegrated D evelopment E nvironment editor compiler linker runtime debugger packaging

Why ZOHO ? Comparable in functionality to any IDE Relational database management feature Visual application development feature Equivalent to Visual Basic + Oracle Zero Cost Nothing to buy or steal ( that is piracy) No extra hardware required Goes beyond any available IDE in terms Rapid Deployment on the web : nothing else required !! Basic security structures in place So what is the catch ? What is missing Very new product, not yet known in the market No demonstrated capability in the corporate world Wonderful tool to learn about application development

BIS07 Application Development - I

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BIS07 Application Development - I