The Effects on the Internet on Family & Employment

18 Apr

The Internet has had many profound effects on family and employment.  It has allowed family members to communicate very easily with each other through e-mail or instant messaging, meaning important news can be quickly spread around the family.  Also, the ability to share family events has been created allowing great memories and holidays to be easily sent to everyone.  However, a negative effect of the Internet is that privacy is greatly decreased leaving parents worried about their children’s safety.

The effects on employment are also very great.  It allows employees to work from their own homes but still keep connected with their office or company. This can be good or bad depending on the nature of work required.  Advertisement and applying for jobs has become a lot easier due to online sites dedicated to advertising job vacancies and online application forms.  For businesses, the Internet allows them to view data from other companies who may be competition which reduces costs of researching the same information by other means.  Another massive effect that the Internet has on business is e-commerce.  This means companies do not have to worry about paying for actual store buildings since they can just keep their stock in a warehouse.  It also allows customers to buy products more easily without having to leave their house, this makes shopping more appealing and may boost sales for the business.

Encryption

11 Apr

RSA – This stands for Rivest, Shamir, and Adelman, the inventors of the technique. The RSA algorithm is based on the fact that there is no efficient way to factor very large numbers. Cracking an RSA key, therefore, requires an extraordinary amount of computer processing power and time.

 

PGP –  Pretty Good Privacy is one of the most common ways to protect messages on the internet because it is effective, easy to use, and free. PGP is based on the public key method, which uses two keys — one is a public key that you disseminate to anyone from whom you want to receive a message. The other is a private key that you use to decrypt messages that you receive.

 

Cipher – Data that has been encrypted. Cipher text is unreadable until it has been decrypted with a key.

 

Symmetric-key Encryption – A type of encryption where the same key is used to encrypt and decrypt the message

 

Public-key Encryption – A system that uses two keys: a public key known to everyone and a private or secret key known only to the recipient of the message. When John wants to send a secure message to Jane, he uses Jane’s public key to encrypt the message. Jane then uses her private key to decrypt it.

 

Digital Certificate – An attachment to an electronic message used for security purposes. The most common use of a digital certificate is to verify that a user sending a message is who he or she claims to be, and to provide the receiver with the means to encode a reply.

 

SSL –  Secure Sockets Layer, a protocol for transmitting private documents via the Internet.

IP Addresses and Subnet Masking

5 Mar

IP Adresses

Class A – the binary number begins with 0 meaning the decimal number can be anywhere from 1 to 126.

Class B – the binary number begins with 10 meaning the decimal number can be anywhere from 128 to 191.

Subnet Masking – this is the process of using a mask to determine what subnet an IP address belongs to. Each IP address consists of 2 parts: the network address and the host address.

Scripting

24 Sep

A script is a list of commands that can be executed by a program. Scripts can be used to extend the functionality of a database management system. A scripting language is easier to learn and use than a full-blown programming language. Scripting languages only let the user select code which will not crash the program.

I used a scripting language to create a button which launches the browser and links the user to a website relevant to the database.

Computer Memory & Memory Adressability

8 Dec

Computer Memory:

  • Main memory – This is temporary storage of programs and files called RAM held on chips.
  • Backing storage – This is known as secondary memory and is not part of main memory.

 Computer Addressability:

This is the way the computer identifies each memory location within main memory.  Each locaton has a unique address so they are easy to find.

The size of the address bus determines how many memory locations can be accessed for example:

1 bit = 2 locations

To calculate the addressable memory of a computer we mulitply the number of storage locations by the size of each location.

The 5 main types of memory:

  • RAM
  • ROM
  • Cache
  • Registers
  • Virtual

 

 

Documentation, Evaluation, Maintenance.

20 Sep

Documentation

The documentation stage is a vital process of making the program usable.  This stage includes creating a User Guide and a Technical Guide.  The User Guide explains how to use your program and makes sure it states very clearly how to do everything that your program can do.  The Technical Guide includes the minimum specification of hardware that is required to run the program e.g. RAM memory, hard disk space and processing speed.  It also includes a specification of what operating systems your program can run on.

Evaluation

The evaluation stage is extremely important as it involves making sure your program  is fit for purpose, that is, does it do what the client wants it to do?  If at this stage you realise that your program is in fact not fit for purpose then you may have to go back to the implementation stage and add or modify the code.

Maintenance

This stage is probably the most important stage of making a program that runs well and is completely fit for purpose.  Maintaining a program can be done in three different ways:

  • Corrective Maintenance
  • Adaptive Maintenance
  • Perfective Maintenance
Corrective maintenance includes changing any errors in the code that cause bugs in the program.  This can be simple syntax errors or functions not operating properly.
Adaptive maintenance is performed when the environment in which the program operates changes, causing the program code to have to be altered to run properly.  This may be an updated operating system or hardware update.
Perfective maintenance is used if the client wishes to add a new feature to the program.  A new piece of code must be created and the program updated.

The Testing Phase

12 Sep

At the moment in computing we are investigating the stages of the Software Development Process.  In particular this week however, we have focused mainly on the testing phase.

Testing a program has a great impact on the cost of the over all project at later stages in the development process.  It is crucial to identify and resolve as many errors as possible during the testing phase and more importantly before the program is released to consumers.  For example, if you have just created a program similar to Microsoft Word and ran a few basic tests to check it is all in order and working correctly so you release it to the public.  Imagine if the majority of customers who bought your product are phoning you up complaining that the program is crashing when they try and carry out a simple task using it.  You will then have to remove every copy of your program from the shelves and fix the bug then re-release it.  This will cost a huge amount of money and time.

There are three main types of test data sets: Normal, Extreme, Exceptional.

  • Normal – This data set is tested to show that the program works correctly using valid input values.
  • Extreme – This data set is used to test the boundary limits within a program, e.g. the highest and lowest values.
  • Exceptional – This is used to show that the program reacts correctly to unexpected or invalid values inputted by the user.
I have learned that the testing phase is much than punching in a few numbers and click the giant go button.  It is actually a pretty substantial stage in building a reliable and robust program for consumers to use with ease and without fear of crashes.