Introduction To The Frameworks

Declarative vs Imperative Paradigms

Imperative programming is a programming paradigm that describes computation in terms of statements that change a program state.But declarative programming is a programming paradigm that expresses the logic of a computation without describing its control flow.

Imperative programming requires developers to define step by step how code should be executed.To give directions in an imperative fashion.But the declarative version ,one says how to do something,the other says what needs to be done.

The declarative style has two advantages over the imperative style .It does not force the traveler to memorize a long set of instructions.It allows the traveler to optimize the route when possible.

Declarative-specify what to do,not how to do it.

Imperative-specify both what and how.

Procedural Programming vs Functional programming

Functional programming focuses on expressions .But procedural programming focuses on statements.

Functional programming is also used when you need to be capable of providing your code is correct.This is much harder to do with procedural programming.

Procedural languages tend to keep of state and tend to execute as a sequence of steps.Purely functional languages don’t keep track of state,use immutable values ,and tend to execute as a series of dependencies.

Functional programming is the same except that functions are first-class values ,so they can be passed as arguments to other functions and returned as results from function calls.

Procedural programming divides sequences of statements and conditional constructs into separate blocks called procedures that are parameterized over arguments that are (non functional)values.

Lambda Calculus In Functional Programming

Lambda calculus is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution.It is a universal model of computation that can be used to simulate any Turing machine.Lambda calculus consists of constructing Lambda terms and performing reduction operations on terms.

Lambda Expressions In Functional Programming

Lambda expressions are essentially blocks of code that can be assigned to variables ,passed as an argument,or returned form a function call,in languages that support high-order functions.They have be part of programming languages for quite some time.some examples include small-talk,Lisp,Ruby,Scala,Python,and more recently,Java and JavaScript.

“No side-effects” In Functional Programming

Functional programming is based on the simple premise that your functions should not have side effects.They are considered evil in this paradigm.If a function has side effects we call it a procedure,so functions do not have side effects.we consider that a function has a side effect if it modifies a mutable data structure or variable ,user IO,throws an exception or halts an error,all of these things are considered side effects are bad is because,if you had them,a function can unpredictable depending on the state of the system ,when a function has no side effects we can execute it anytime ,it will always return the same result,given the same input.

“Referential Transparency” In Functional Programming

A function that returns always the same result for the same input is called a pure function .A pure function,therefore is a function with no observable side effects,if there are any side effects on function the evaluation could return different results even if we invoke it with the same arguments.we can substitute a pure function with its calculated value.

Key Features Of Object Oriented Programming

Abstraction

Abstraction is the process of removing characteristics from 'something 'in order to reduce it to a set of essential characteristics that is needed for the particular system.

Encapsulation

It is the process of grouping related attributes and methods together,giving  a name to the unit and providing an interface for outsiders to communicate with the unit.

Information Hiding

Hide certain information or implementation decision that internal to the encapsulation structure(class).

The only way to access an object is through its public interface

·       Public – anyone can access/se it

·       Private – no one except the class can see/use it

Generalization/Inheritance

Child class is a type of the parent class.

Used to showcase reusable elements in the class diagram.

Child classes “Inherit” the attributes and methods defined in the parent class.

Polymorphism

In programming languages and type theory, Polymorphism is the provision of a single inheritance to entities of different types or the use of a single symbol to represent multiple different types.

Event-driven Programming

Event-driven programming is a paradigm used to structure a program around various events.These events include user input events in graphical user interfaces and networking requests from websites and other online properties.

Until the invention of graphical user interfaces most programs simply waited for users to enter a command through their keybord in the meantime.the program would simply wait The creation of graphical interfaces and the windows paradigm.however ,forced developers to rethink their earlier strategies .Because users can click virtually anywhere ,the program must be read for nearly any input.In addition ,information isn’t always entered in the same manner,event =-driven programming makes it easier to handle a divers range of inputs.

Event-driven programming is significantly harder for beginners than other programming paradigms .so most instructional courses and books avoid teaching it at first.After gaining skills in more traditional programming techniques.however most students are able to understand and use it.

Compiled Languages,Scripting Languages and Markup Languages

A major feature of scripting languages is that they need not be compiled .so that they are faster to modify and quickly check Markup languages are completely different.They designed not for general purpose programming ,but for processing or presentation of text HTML,XML,LATEX are considered as markup languages .the compiled language is a programming language whose implementations are typically compilers and not interpreters.so there are some unique differences in compiled language,scripting language and markup language.

Role Of Java Virtual Machine

A java virtual machine is a virtual machine that enables a computer to run java program as well as programs written in other languages that are also compiled to java byte-code. The JVM is detailed by specification that formally describes what is required of a JVM implementation.Having a specification ensures interoperability of java programs across different implementations so that program authors using the java Development kit(JDK)need not worry about idiosyncrasies of the underlying hardware platform.

The JVM references implementation is developed by the OpenJDK project as open source code and includes a JIT compiler HotSpot.The commercially supported java releases available from Oracle Corporation are based on the OpenJDK runtime.

Execution Of JavaScript

Execution context(EC)is defined as the environment in which javaScript codeis executed.javaScript is what is called a client –side Scripting language.That means thst it is a computer programming language that runs inside an Internet browser (a browser is also known as a web client because it connects to a web server to download pages.)The way javaScript works is interesting .Inside a normal web page you place some JavaScript code (see How web pages work for details on web

pages).When the browser loads the page,the browser has a built-in interpreter that reads the JavaScript code it finds in the page and run it.

How the output of an HTML document is rendered

The HTML output consists of multiple HTML documents. The page break element determines where a page is created. Unicode data appears as unicode if the output font can display the characters.

CASE software types

Individual tools-for specific task.

Workbenches-multiple tools are combined ,focusing on specific part of SDLC.

Environments- combines many tools to support many activities throughout the SDLC.

Plugins

Plugins provide specific tools for development.

At development time

·       The plugin(source code files,modules,packages,executable)is placed in the project,

·       Apply some configurations using code

At run-time
     ·       The plug-in will be invoked via the configurations

Libraries

Libraries provide an API ,the code can use it to develop some features,when writing code.

At development time

·       Add the library to the project (source code files,modules,packages,executable)

·       Call the necessary functions/methods using the given packages/module /classes

At run time

·       The library will be called by the code.

Frameworks

Framework is a collection of libraries ,tools,rules,structures,and control,to build software systems.

At development time

·       Create the structure of the application.

·       Place your code in necessary places.

·       You may use the given libraries to write your code.

·       You can include additional libraries and plugins

At run-time

·       The framework will call your code(inverse of control)