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Using and understanding Internet services

Internet services Internet services


of 25 4th September 2017

http://www.open.edu/openlearncreate/course/view.php?id=2770



Contents

1 What are Internet services? 2 The WWW as a service 3 The WWW and web crawlers 4 The WWW and search engines 5 Email 6 File transfer 7 Report concerns 8 Activities 9 Additional resources 10 End of course quiz 11 Acknowledgements





1 What are Internet services? The Internet is a collection of interconnected

computers, sharing data and services. A service is a

program running on a computer that allows you to

perform a useful activity such as:

browsing the World Wide Web (WWW)

sending and receiving email

downloading video and music files

communicating with friends and family

using voice and video.

Many of the services supported by the Internet operate

as client/servers. This allows one device (server) to

provide a service to a requesting device (client):





Figure 1

In many smaller networks, devices operate as peers.

This is where devices can behave as either client or

server, depending on which services they are using.

This operation is referred to as peer-to-peer, and is

commonly found in home networks as it is easily

configured. The mode of operation is difficult to use

within larger networks, but it is often used within

Internet-based file sharing services.





Figure 2





2 The WWW as a service The WWW operates using clients and servers. Web

pages are stored on servers connected to the Internet,

and your PC uses a web browser acting as a client to

access pages stored on the servers:

Figure 3

Watch this video on web services to find out more:

Watch the video at YouTube.com.




https://www.youtube.com/v/iaCQG4ELu1I&hl=en&fs=1&rel=0


3 The WWW and web crawlers The WWW consist of an extremely large collection of

web pages (more than 4 billion in 2017) stored at

more than a billion websites. You can view the current

numbers here.

Because of the speed at which websites are being

added to the WWW, finding sites you are interested in

can be quite a challenge. You have probably used a

search engine to find web pages, but how do they

know about all the new websites continually being

added to the WWW?

Figure 4




http://www.internetlivestats.com/watch/websites/


Search engines use special computer programs called

web crawlers to automatically learn about new content

when it is added to the WWW.

Web crawlers browse the WWW in a methodical

manner, copying web page content, including Uniform

Resource Locators (URLs) linking to other web pages

and sending it to the search engine. This information

is then processed by the search engine, which stores

key words and information in such a way it can be

accurately searched by web users. This processing of

web page information collected by web crawlers is

called indexing.

The URLs used by web crawlers provide a unique

identity for each web page, and indicate where it is

stored:

Figure 5

When a web crawler is started, it is provided with a list

of URLs (called seeds), which it then visits. It collects

all the URLs of hyperlinks it finds at these sites. These

are then added to the list of sites for the web crawler





to visit, providing an expanding set of pages to search

and copy:

Figure 6

Due to the size of the WWW, and the rate at which it

grows, web crawlers are not able to search all the

pages in existence while also checking known pages

for updates. Even large search engines like Google

have not indexed the entire WWW.





4 The WWW and search engines When you try to find a web page using a search

engine, the search engine looks through the index of

the pages created by the web crawler.

The search engine will examine the search term and

compare it against the index of information it holds for:

how often the search words occur on a

page

where they are on a page

if they occur together

if there are similar words.

It uses this information to choose web pages that it

considers to best meet your search request. The

pages are then displayed in order, with the ones

meeting the search term best being shown at the top.

Some search engines (e.g. Google) use the concept of

rank when presenting search results. This considers

the amount of links on other relevant websites

pointing towards a particular page. The more links

from related web pages, the higher the ranking.

Search engines accept payments from commercial

organisations to place their web pages higher up the





displayed list from a given search, even if their page is

not a particularly good match.

This is a form of advertising, and the search result will

be marked with ‘Ad’ to indicate this:

Figure 7

To learn more, take a look at the following videos:

Matt Cutts’s video on ‘How Search Works’.


Google’s video, ‘Verbatim and double

quotes’, on search terms.


Activity: WWW searchesDemonstrate that you can perform WWW searches by carrying out

some research into one of the following topics:

1. Biology: Use a search engine to find out about the

tree octopus. What is it? Where is it found? Is it a real

species? Provide your answer...




https://www.youtube.com/v/QMfEqQxXoO8&hl=en&fs=1&rel=0

https://www.youtube.com/v/BNHR6IQJGZs&hl=en&fs=1&rel=0


1. Chemistry: As you study more science at school

you will come across many weird and wonderful

chemicals. One you will never be told about because

it is a secret is dihydrogen monoxide. What can you

find out about it? Provide your answer...

1. Geography: The Earth is a diverse planet, and is

home to many species of animals, many of which are

endangered. Identify an endangered animal from each

of the Earth’s continents:

Asia Provide your answer... Africa Provide your answer... North America Provide your answer... South America Provide your answer... Antarctica Provide your answer... Europe Provide your answer... Australia Provide your answer...





5 Email Electronic mail or email provides a way of exchanging

digital messages across computer networks. The

messages can consist of just simple text, but you can

also attach a variety of different files (e.g. documents,

pictures, videos).

Email works as a client/server service, and allows you

to create emails using client software (e.g. Outlook,

Thunderbird) which then transfers the emails to mail

servers where they are stored until retrieved by the

email recipient. This means you only need to connect

briefly to the Internet to send and receive emails.

Figure 8

To use email, you need an email address, which

uniquely identifies a user with an account on a of 25 4th September 2017




particular mail server. The address consists of a local

part, identifying the user’s mailbox, and a domain

name which identifies the mail server location:

Figure 9

Many email services are now web based, so you can

write, send and receive email via a web browser after

you have set up an account with an online email

provider, such as Google or Yahoo!

Take a look at this video for more information about

email.





https://www.youtube.com/v/IGu2NBVTbPk&hl=en&fs=1&rel=0


6 File transfer There are many different services available allowing

the transfer of files across a network. Most computer

operating systems (e.g. Windows, Linux) allow you to

set up a peer-to-peer network at home so you can

share files and other resources, such as Internet

access and printers.

These services may not work correctly if you have

devices using different operating systems, so file

transfer protocols need to be capable of working

regardless of the operating system you are using:

Server Message Block (SMB) allows

the sharing of files and printers within a

Local Area Network. Although it was

originally supported by just Microsoft

operating systems, it is now supported by

Apple and Linux operating systems too. It

operates as a peer-to-peer service.

File Transfer Protocol (FTP)

provides a client/server service for

transferring files across the Internet. It is

supported by a wide range of different

operating systems, and is also built-in to





many software programs supporting file

transfer.





7 Report concerns The Internet provides many useful and entertaining

services, but due to its global nature, it is very difficult

to regulate. This means, as well as many legal uses,

the Internet can also be used to support illegal

activities.

If you have concerns about something you have seen

on the Internet, there are a variety of organisations

that you can turn to:

National Crime Agency’s Child Exploitation and Online Protection Centre

Figure 10

If you or a friend are suspicious about the way someone you have

met online is behaving towards you, or they are asking you to do

things that you feel uncomfortable with, report it to the Child

Exploitation and Online Protection Agency (CEOP).

This often starts with meeting some online and not really knowing

who they are. If you feel uncomfortable get out and report it.

Internet Watch Foundation of 25 4th September 2017




Figure 11

You should report any material you find online to the Internet

Watch Foundation (IWF) that shows:

pictures of children being sexually abused

criminal obscene pictures.

Parent Port

Figure 12

You can report any concerns you or your parents have over what

you see and hear in the media to Parent Port. This includes

content on the Internet, such as:

a movie, game or advert that makes you feel upset, or

is unsuitable for your age group





any other material online that is not suitable for your

age and makes you feel surprised it is there.

True Vision

Figure 13

If you find people being horrible online and trying to get you or

groups of people to be horrible to others because of their religion,

sex or where they come from, this may be a hate crime and is a

criminal offense. You can report it to True Vision.

Watch the online video about Digital Safety,

Responsibility and Awareness to learn more about

staying safe on the Internet.





https://www.youtube.com/v/IN9xqVYejAI&hl=en&fs=1&rel=0


8 ActivitiesIndividual Activities

1. Complete the KidSMART Treasure Hunt worksheet.

2. Play the Digital Citizen game.

Activity for the whole class: Web and email services (Packet Tracer)The Internet is made up of computers connected together in

groups. These groups are also all connected together. But the

Internet also includes computers connected at home to Internet

Service Providers. In addition, when we are out and about we can

connect our smart devices over 3G and 4G networks to the

Internet.

How does all this connectivity work? Explore web and email

services for Bob and Ann using Packet Tracer and the Blue Lab

Book.

You will need:

Lab Book: Select and Use Internet Services Packet Tracer CASBIT.pkz




http://www.open.edu/openlearncreate/mod/oucontent/olinkremote.php?website=Internet%20services&targetdoc=CASBIT

https://www.netacad.com/courses/packet-tracer-download/

http://www.open.edu/openlearncreate/mod/oucontent/olinkremote.php?website=Internet%20services&targetdoc=Lab%20Book:%20Select%20and%20Use%20Internet%20Services

http://digizen.org/resources/cyberbullying/interactive/

http://www.open.edu/openlearncreate/mod/oucontent/olinkremote.php?website=Internet%20services&targetdoc=KidSMART%20Treasure%20Hunt


9 Additional resourcesFor more information, take a look at the following resources.

BBC Bitesize - How Do Search Engines Work BBC Bitesize - Believing everything on the web BBC Bitesize - Communicating Online Searching Google - A detailed document called

‘Google Guide’, describing lots of ways to search

using the power of Google

How Stuff Works Search Engines




http://computer.howstuffworks.com/internet/basics/search-engine.htm

http://www.googleguide.com/category/overview/index.html

http://www.bbc.co.uk/guides/z9r72hv#zqdhpv4

http://www.bbc.co.uk/guides/zt9thyc

http://www.bbc.co.uk/guides/ztbjq6f#zs4mxnb


10 End of course quizNow it’s time to test what you’ve learned in a quiz.




http://www.open.edu/openlearncreate/mod/oucontent/olinkremote.php?website=Internet%20services&targetdoc=Using%20and%20understanding%20Internet%20services%20quiz


11 AcknowledgementsGrateful acknowledgement is made to the following sources:

Figure 1: Adapted from a Cisco Image








Figure 10: Child Exploitation and Online Protection Agency

(CEOP)

Figure 11: Internet Watch Foundation

Figure 12: Parent Port

Figure 13: True Vision





Every effort has been made to contact copyright holders. If any

have been inadvertently overlooked the publishers will be pleased

to make the necessary arrangements at the first opportunity.




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