This Assignment is the continuation of First Assignment. Take same case study given in Assignment 1 (also provided at the end of this assignment); apply the techniques and methods from lectures (7-13) in order to finalize the tasks of second assignment listed below in task description.
Please refer to the case study given in assignment no. 1 as well as to the solution of assignment 1.
Note: Same case study is also given at the end of this assignment for your convenience.
In this assignment you will focus on the task given below:
Draw a comprehensive ER-diagram along with their relationships and cardinalities.
You have to perform all the necessary steps that are included in the above task in your solution file.
Drawing Final ER Data Model:
You can use any tool for drawing like MS Office or Visio.
Important things to consider:
Suppose we have a wireless ad hoc network. A wireless ad hoc network is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre existing infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for other nodes, so the determination of which nodes forward data is made dynamically on the basis of network connectivity.
Nodes in the ad hoc network has unique id that identify it across the network. Each of the nodes uses a certain protocol.
Various protocols are used including aodv, dsdv, dsr etc. There are various version of a specific protocol. An ad hoc network typically refers to any set of networks where all devices have equal status on a network and are free to associate with any other ad hoc network device in link range.
Nodes in the ad hoc networks send packets to each other. Each packet has two parts namely: header and data. Header information contains source destination address and some other information. Each packet is sent on one of the route based on the source destination address. There can be several hopes around one route. Every route is assigned a weight based on some pre defined rule.
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Tariq bro, i think cardenality b/w Packet and header is not one to many but one to one....
yeah furqan u r rit beauce every packet have single header and vice versa
Thank u r sharing :)
An entity-relationship diagram is a data modeling technique that creates a graphical representation of the entities, and the relationships between entities, within an information system.
The three main components of an ERD are:
The entity is a person, object, place or event for which data is collected. For example, if you consider the information system for a business, entities would include not only customers, but the customer's address, and orders as well. The entity is represented by a rectangle and labelled with a singular noun.
The relationship is the interaction between the entities. In the example above, the customer places an order, so the word "places" defines the relationship between that instance of a customer and the order or orders that they place. A relationship may be represented by a diamond shape, or more simply, by the line connecting the entities. In either case, verbs are used to label the relationships.
The cardinality defines the relationship between the entities in terms of numbers. An entity may be optional: for example, a sales rep could have no customers or could have one or many customers; or mandatory: for example, there must be at least one product listed in an order. There are several different types of cardinality notation; crow's foot notation, used here, is a common one. In crow's foot notation, a single bar indicates one, a double bar indicates one and only one (for example, a single instance of a product can only be stored in one warehouse), a circle indicates zero, and a crow's foot indicates many. The three main cardinal relationships are: one-to-one, expressed as 1:1; one-to-many, expressed as 1:M; and many-to-many, expressed as M:N.
The steps involved in creating an ERD are:
Identify the entities.
Determine all significant interactions.
Analyze the nature of the interactions.
Draw the ERD.
See This it will be helpfull
thanks alot haroon khan....its really helpful for develop relationships :)
nice but kch smj nhi a rhi es ki
same mjy b
yes mujay bi nahi aai