### Activity 4

In Block 1 Part 3 you met the idea of client–server communication. Which parts of an instant messaging session (as illustrated in Figure 3) are client–server communication, and which are not?

( figure 3 is an animation on the TU100 site. )

client – server communications:

• Checking which of the users friends are online is done through the server.

client – client communications:

• The conversation itself does not have to go via the server.

### Activity 5

The quotation below is from a student at a face-to-face university who was interviewed about their use of IM. You will notice that the quotation refers to MSN, which was the name used at the time for the instant messaging application Windows Live Messenger.

There is a case for people being on MSN and being on it too long. You know, if you allow it to interfere with your coursework here and your work studies here, it can become … like you need to know when to stop and … like if you saw people coming up in your Messenger and you’re online. If you just made an attempt to always start off a conversation, you could be on it for always, without even knowing that time passed.

Quoted in Rutter, 2009, p. 37

What are your views on instant messaging? Is it useful when you are studying, so that you can contact other students for help and support? Or is it too much of a distraction or interruption?

I personally do not use IM for my studies, relying on the forum to communicate with my fellow students. This is mainly due to previous experience and knowing how distracting it can be.

### Activity 6

What are the main similarities and differences between instant messaging and chat?

Whilst both systems are asynchronous and mainly text based the similarities end there. In IM you can choose who is on your friends list and when you talk to them, whilst in chat anyone can join the chatroom and contribute to whatever is being discussed at the time. This however is changing as online chatrooms and IM applications can now both offer the capabilities of each other.

### Activity 4

Take a few minutes to think about when it is appropriate to email and when to blog. You could make a note of your response in your own blog.

e-mail is more suited for correspondents between known people, whereas a blog is suited for topics which the author wishes to share and openly discuss.

### Activity 5

Take a look at the examples of blogs listed below. Only two of them have a facility for readers to add comments. Do you think this facility is important for a blog? Can you see any potential problems with it?

As a blog owner myself, I like to see how others answer questions, to see what others think on the same topic. For newsblogs, and other people who simply wish to share information, the facility for others to add responses is not required.

The problem is that if you do not moderate the responses from others on your blog then you open the blog up to spam, flaming, and trolling behaviour from malicious people who can access your blog.

### Activity 6

How do you think the speakers at such events might feel, knowing that their every word is being commented on?

Excerpt from the Open University TU100 course material:

Bloggers write about where they work, their interests, politics, recent news items, their cats and many other things. Because blogs can be updated quickly, and postings can be made from mobile devices, blogging can be used to update the Web about an event as it is happening. This is referred to as ‘live blogging’, and is becoming popular at political events and conferences. Where a number of bloggers are blogging at the same event, those unable to attend can gain a range of perspectives. For example, microblogging – a specific type of blogging that you will meet later in this part – can be used by participants at events to help keep non-participants in touch with what is happening.

I think that the speakers would have already prepared their material for reception by an audience, but being aware of the larger audience, and the nature of the medium their words will be transmitted through may cause them to re-think their wording,a s well as how they express their points and opinions.

### Activity 5

Which of the following can be copyrighted? A comic book, an Open University podcast, an abstract painting, the design of a car.

All of these things can be copyrighted.

### Activity 6

1. Is this text protected by copyright?( in  course material )
2. When will the copyright expire on the Beatles’ original recording of their song ‘Yellow Submarine’ (released in 1966)?
3. When will the copyright expire on the song ‘Yellow Submarine’, which was written by Paul McCartney and John Lennon?
4. Bleak House by Charles Dickens was published in 1853. Is the original text still under copyright?
1. Yes, the OU course material is protected by a copyright which can be found near the start of each Block and Section.
2. In accordance with current copyright law, the song ‘Yellow Submarine’ will no longer be protected by copyright in 2016.
3. Again, according to current copyright law, and the terms of the copyright itself, the copyright will expire 70 years after the last living artists death.
4. ‘Bleak House’ is in the public domain, and has been since approximately 1940 ( 70 years afer the death of Charles Dickens ). Whilst the original Text is public domain, any publisher can create their own typographically unique version of the book and sell it under their own 25 year copyright.

### Activity 5

Excerpt from the Open University course TU100 material:

So far you have seen that data itself can be remarkably resilient; its lifetime is largely limited by the medium on which it is stored. Paper rots, magnetic disks gradually lose their coatings and even optical discs are consumed by the air. Long-term threats to our data are serious enough, but we must also consider everyday threats including:

• accidentally deleting a file or program
• losing disks, computers or memory cards
• hardware failures such as a hard disk crash
• software bugs that prevent data being written to a storage device or cause it to be corrupted as it is written
• disasters such as fire or flooding
• crimes including terrorism, theft and acts of sabotage such as hacking.

Look at the list of risks to data above. Do you think any of them apply to you and your computer?

All of the above apply to most PC users, either at home or work.

### Activity 6

Why should we migrate data regularly, and why should we make more than one copy?

Migrating data makes sure that the backup copy is relatively new, minimising the risk of it having degraded over time, and keepign any changes to the data stored to ( such as additions to your personal files, or updates to a companies trading hiistory ). Having multiple backups also helps add a layer of redundancy too the data too, and using different media would help to preserve the data against the different shorcomings of the storage media.

### Activity 6

In the previous session, I looked at how it is possible to work out a location by measuring angles between reference points – a technique known as triangulation. It is also possible to use distance measurements to perform triangulation, and this is the idea that underpins the operation of GPS.

The animation in Figure 10 starts by considering distance-based triangulation, before going on to show how GPS operates by applying a similar technique in three dimensions. Click anywhere on the image below, then click on the triangle to play the animation. You will need your computer’s speakers or headphones to listen to the audio. When you have finished, write a short explanation (about 150 words) of how the GPS system enables a receiver’s location to be determined.

The animation here, can only be accessed by those with a valid OU login ( it is unknown at the time of writing this post if you must also be enlisted on the course TU100 as well ).

Transcript of Figure 10 GPS introduction from TU100 course material.

The location of the GPS receiver is first calculated via spherical geometry, where  several satellites gauge their relative distances from the receiver on the Earths surface, by working out the intersections of the spheres represented by the range to the receiver, it’s location can be represented by the single point on the Earths surface at which they all intersect ( a common point on all of the satellites spheres ). This data is then changed into a latitude and longitude, or other standard coordinate system for use by the receiver.

### Activity 7

Popular journalism often refers to satellites surveying or ‘tracking’ the movements of individuals or vehicles. Briefly summarise why this is wrong in the context of GPS.

this is incorrect as the GPS unit that people use are receive only devices, which use the data and signals transmitted from the GPS satellite constellation to calculate it’s position, it has no active tracking facility, the satellites are not aware of the location of every / any GPS receiver.

There are many other online services I could have used for the same sorts of things. By searching the Web, what alternatives can you find for sharing files, creating and storing notes, managing photographs and discovering new music online? Don’t spend too long on this.

Note sharing:

• Evernote
• Cloud note

Sharing Files:

• Skydrive
• DropBox
• Rack Space
• Sahre File
• filocity

Photograph storage and sharing:

• flickr
• picasa
• photo bucket

Music:

• lastfm
• soundcloud
• spotify
• grooveshark

Calculate the duty cycle of a device that typically connects to a network and transmits for 20 ms in every 0.5 s. You may wish to use a calculator for this activity.

So we have the following figures:

1 cycle $= 0.5\, seconds$

Duty time per cycle $= 20\, ms = 0.020\, seconds$

So to work out 0.020 as a percentage of 0.5 :

Duty cycle $= \large{\dfrac{0.020}{0.5}\cdot 100\%}$

Duty cycle $= \boldsymbol{\underline{\underline{4\%}}}$

So what is the mean BMI of our sample above?

given the following information from the course material:

Calculating the mean manually for large data sets would clearly be tedious, and professional statisticians use computer tools instead. However, just glance at the normal distribution in Figure 5 and the mean jumps out at you: it’s the BMI at which the curve reaches its highest point. Note, though, that this is true for the normal distribution only. As you will learn later in the part, there are other distributions that don’t have this property.

Column chart of full set of numbers counted in each BMI group.

It appears that the mean BMI is 27.

Write three bullet points on why the advent of digital media revealed the long tail of demand.

• The first bullet point should describe pre-filtering and why it was common when media content was stored on physical carriers.
• The second bullet point should introduce post-filtering and how it was made possible.
• Finally, the third bullet point should describe the main consequence of the move from pre- to post-filtering.
1. Before the advent of digital media, pre-filtering prevented the general consumer from even being aware of the existence, let alone the availability of certain media, this was to maximise profit on “high demand” media that made it past the pre-filtering stage.
2. Post-filtering is where the user / consumer can tell the provider what media they like and want to be exposed to. This was made possible largely by the introduction of digital media, which changed the storage of media from store shelves to servers, allowing for a far greater range of media to become available to the consumer.
3. The move from pre to post-filtering has allowed providers to supply a far greater range of media to the consumer, as well as allowing smaller-scale artists and producers to “break into” the market, whereaas before they would have suffered from pre-filtering. post-filtering also allows the consumer to actively choose what they do and do not like out of a large range of media.