There are two fundamental protocols in the transport layer 1. TCP Transmission Control Protocol-- connection-oriented protocol 2. UDP User Datagram Protocol -- connectionless protocol Connection-oriented communication : establishes a logical (virtual) connection prior to sending data. Connectionless communication : sends data right away without establishing a logical connection Qn why do we have transport layer protocal? IP provides a weak, but efficient service model (best-effort ) How should hosts send into the network? i.)Flow Control ii.) Too fast is bad; too slow is not efficient IP packets are addressed to a host How to decide which application gets which packets? NOTE TRASPORT LAYER IS RESPONSIBLE FOR PROCESS TO PROCESS DELIVERY PORTS port is a communication endpoints Since there are many applications running on a computer, there is a need to decide which application gets which packet. A port number is a way to identify a specific application (proc
Definition of Terms
Object-Oriented Design
This is concerned with developing an object-
oriented model of a software system to implement
the identified requirements. The objects in an
object-oriented design is related to the solution to
the problem. There may be close relationships
between some problem objects and some solution
objects, but the designer inevitably has to add new
objects and to transform problem objects to
implement the solution.
Object-Oriented Programming
This is concerned with realizing a software design
using an object-oriented programming language,
such as Java or C++. An object-oriented
a programming language provides constructs to
define object classes and a run-time system to
create objects from these classes.
An Object
An object is an entity that has a state and a defined
set of operations that operate on that state. The
state is represented as a set of object attributes.
The operations associated with the object provide
services to other objects (clients) that request these
services when some computation is required.
An Object ...
Objects have state, behavior, and identity and are
created according to an object class definition. An
object class definition is both a type specification
and a template for creating objects. It includes
declarations of all the attributes and operations that
should be associated with an object of that class.
A Class
A class is a set of objects which have a common
structure and common behavior. An object is an
instance of a class. A class represents the abstract
matrix of an object before its instantiated
Attribute
This is an observable property of the objects of a
class.
Method
This is an operation that can update the value of
the certain attributes of an object E.g. We will add a
public method to access the age (then it's going to
be a method that does not change any attribute of
our object), and another to modify this age. These
two methods are commonly called getters and
setters.
class Person { private: int Age; public: int GetAge() {
return Age; } public: void SetAge(int newAge) { Age
= newAge; } };
State
The state of an object encompasses all of the (usually
static) properties of the object plus the current
(usually dynamic) values of each of these properties.
Identity
Identity is that property of an object which
distinguishes it from all other objects
Behavior
This is how an object acts and reacts, in terms of its
state changes and message passing; the outwardly
the visible and testable activity of an object
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