Wednesday, 3 June 2020

2074-Solution of Computational Course (Computer Science) : Long Answer Question

Long Answer Question


Attempt any TWO questions.


1) Discuss in detail about the TCP/IP protocol suite. How TCP protocol differs from the UDP? (6+4)

Ans: 
Communications between computers on a network is done through protocol suites. The  most widely used and most widely available protocol suite is TCP/IP protocol suite. A protocol suite consists of a layered architecture where each layer depicts some functionality which can be carried out by a protocol. Each layer usually has more than one protocol options to carry out the responsibility that the layer adheres to. TCP/IP is normally considered to be a 4 layer system. The 4 layers are as follows:
  1. Application layer
  2. Transport layer
  3. Network layer
  4. Data link layer
Application Layer:
This is the top layer of TCP/IP protocol suite. This layer includes applications or processes that use transport layer protocols to deliver the data to destination computers.
Application layer has various protocols that applications use to communicate with the second layer, the transport layer. Some of the popular application layer protocols are:
  • HTTP (Hypertext Transfer Protocol)
  • FTP (File Transfer Protocol)
  • SMTP (Simple Mail Transfer Protocol)
  • SNMP (Simple Network Management Protocol)
Transport Layer:
This layer provides backbone to data flow between two hosts. This layer receives data from the application layer above it. There are many protocols that work at this layer but the two most commonly used protocols at transport layer are TCP and UDP.
TCP is used where a reliable connection is required while UDP is used in case of unreliable connections.
Use of TCP- while downloading a file, it is not desired to loose any information (bytes) as it may lead to corruption of downloaded content.
Use of UDP- while streaming video, loss of few bytes of information due to some reason is acceptable as this dose mot harm the user experience much.

Network Layer (Internet Layer):
This layer organize or handle the movement of data on networks. By movement of data, routing of data is done by this layer. The main protocol used at this layer is IP. While ICMP and IGMP are also used at this layer.

Data Link Layer (Network Interface Layer):
This layer normally consists of device drivers in the OS and the network interface card is attached to the system. Both the device drivers and the network interface card take care of the communication details with the media being used to transfer the data over the network. Some of the famous protocols that are used at this layer include ARP (Address Resolution Protocol), PPP (Point to Point Protocol), etc.

Here is the difference between TCP and UDP,
TCP (Transmission Control Protocol)
UDP (User Datagram Protocol)
Reliability
  1. It is connection oriented protocol.
  2. There is no corruption while transferring a message.
  1. It is connection less protocol.
  2. There may be some corruption while transferring a message.
Ordered
3) If you send two messages along a connection, one after another, the first message will reach receiver first i.e. data arrives in order.
3) If you send two messages out, you don’t know what order they will arrive.
Heavyweight
4) When data arrives in wrong order, all the out of sequence parts have to be put back together so requires a bit of work.
4) No ordering of messages so it is a lot quicker and the network cars/OS have to do very little work to translate the data back from the packets.
Streaming
5) There may be multiple packets per read call.
5) There is one packet per one read call.
Examples
WWW (Apache TCP port 80), FTP (FTP port 21), etc.
Domain Name System (DNS UDP port 53), Trivial File Transfer Protocol (TFTP), etc.


2) Define DBMS. Discuss different types of data models with suitable example. (2+8)

Ans:
A database management system (DBMS) is the set of programs that is used to store, retrieve and manipulate the data in convenient and efficient way. The main goal of DBMS is to hide complexities of data management from users and provide easy interface to them. Examples of DBMS structure are Oracle, Sybase, Microsoft SQL Server, Dbase, etc.

A database model is an abstract model that describes how the data is represented and used.
It consists of a set of data structures and conceptual tools that is used to describe the structure (data, types, relationships and constrains) of a database. Different database models which are used to design and develop the database of the organization are:
  1. Hierarchical model
  2. Network model
  3. Entity-Relationship model
  4. Relational model
  5. Object oriented model
  6. Object-relational model
  1. Hierarchical Model (Tree-like) : The oldest type of data model developed by IBM in 1968. It is the record based representational or implementational data model.
    In this model, different records are inter related through hierarchical or tree like structure.
    For example: A parent record can have several children, but a child can have only one parent. It therefore represents only one and one-many relationships.
  2. Network Data Model : It is an extension of the hierarchical database structure. It is also record based representational or implementational data model.
    It is more flexible than old data model.
    It describes data and relations between data by using graph rather than tree like structure.
    In hierarchical data model, a child cannot have more than one parent but it is allowed in network data model.
  3. Entity Relationship Model : It is based on a perception of real world that consists of a collection of basic objects called entities and relationship among these subjects/objects.
    In this model, a database can be modeled as a collection of entities and relationship among entities.
    It is one of the conceptual data model and describes the information used by an organization in a way that is independent of any implementation level issues and details.
    Database can be expressed graphically by E.R. diagram.
  4. Relational Model : It is also representational or implementation data model. In this data model, unlike the hierarchical and network models, there are no physical links.
    All the data is maintained in the form of tables (generally known relations) consisting of rows and models.
    Thus, the relational model has become more programmers friendly and much more dominant and popular in both industrial and academic scenarios.
  5. Object Oriented Data Model : Based on object oriented programming paradigm, a core object oriented data model consists of following basic object oriented concepts.
    a) object and object identifier
    b) attributes and methods
    c) class
    d) class hierarchy and inheritance

3) Mention the applications of GIS. Discuss in detail about the GIS Data Models. (2+8)

Ans:
A Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze, manage and present all types of geographical data. The applications of GIS are as follows:
  1. Local Government
  2. Real Estate and Marketing
  3. Public Safety and Defense
  4. Natural Resources Exploration
  5. Transportation
  6. Health Management
  7. Public Health and Epidemiology
  8. Geospatial Industry

GIS Data Models
As GIS is based on data, hence there must be a data model that has to be followed to standardize procedure. They are:

  1. Spatial data models - Spatial data describes absolute and relative location of a geographic features and is classified as  (a)Raster Data  (b)Vector Data  (c)Image Data. A data model is a way of defining and representing real world surfaces and characteristics in GIS.
  2. Attribute data or non-spatial data - Attribute data describes the characteristics of the spatial features which can be quantitative or qualitative in nature.
Spatial Data Model

1) Vector Data Model: It uses discrete points, lines or areas corresponding to discrete objects with name or code number of attributes.
Advantages:
  • Data can be represented at its original resolution and form without generalization.
  • Graphic output is usually more aesthetically pleasing.
  • Accurate geographic location of data is maintained.
  • Since most data (eg. Hard copy maps) is in vector form, no data conversion is required.
  • Allows for efficient encoding of topology, and as a result more efficient operations that require topological informations.
Disadvantages:
  • Location of each vertex needs to be stored explicitly.
  • For effective analysis, vector data must be converted into topological structures.
  • Topology is static and any updating or editing of the vector data requires rebuilding of the topology.
  • Algorithms for manipulative and analysis function are complex and may be processing intensive.
  • Often this inherently limits the functionality of large data sets.

2) Raster Data Model: It is a regular grid of cells divided into rows and columns. An element of the  grid cell is to called a pixel (picture cell).
Advantages:
  • It is a simple data structure.
  • It has the ability to represent continuous surfaces and performs surface analysis.
  • The ability to uniformly store points, lines, polygons and surfaces.
  • The ability to perform fast overlays with complex database or sets.
  • Also compatible with digital satellite imagery.
Disadvantages:
  • There can be spatial inaccuracies due to limits imposed by raster data set cell dimension.
  • Raster datasets are potentially very large. Resolution increases as the size of cells decreases. Thus cost and disk space used also increases.
  • There is also a loss of precision that accompanies restructuring data to a regularly spaces raster cell boundary.
  • Raster maps normally reflects only one attribute or characteristic for an area.
Attribute Data Models (Non-spatial data)
Attribute data is information appended in tabular format to spatial features. A separate data model is used to store and maintain attributes data for software.


Click here for 2073-Long Answer Question
Posted by at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)