Alvin's Educational Technology Blog

Yesterday I explained how to use a zip utility to make files smaller before sending them across the Internet.  You should always use a zip utility, but you should avoid sending attachments if at all possible.

There are some efficiency issues.  Here is part of a previous post on the subject:

Do you realize the process involved in sending someone a file attachment? Since email is based on ASCII text, the email attachment must be converted to ASCII using Unix to Unix Encoding. This makes the file roughly twice as big as the binary version. This doesn’t include the extra overhead that is created by all the formatting code that goes into most binary files. An ASCII page of text is 2k. Copy the same text into Word and it becomes 4k. UUE the 4k and becomes 7k. So attaching a one page text document is like sending three and half pages of email.

Last year I received over 300 MB of file attachments. Most were only a few megabytes. The largest was 12 megabytes. If I consider only the attachments (not the accompanying email), this was more than three times the capacity of my inbox. Most of these attachments could have been avoided if senders would send links to files instead of attachments. With all the content management systems that we use to hold our information, emailing a link to something instead of an attachment saves everyone time. If I need the information, I can follow the link and I don’t have to clean it out of my attachment folder.

The last two sentences are the most important.  It is easy to give someone a link to a file instead of attaching the file.  If you have a photo you want someone to see, give them a link.  Here is a picture I took last week.  Click the link to see it.

http://farm2.static.flickr.com/1308/634778526_04a7fc36a8_o.jpg

The number one method of spreading a virus is through email attachments.  In the last four days I have averaged six infected attachments each day.  My anti-virus program weeds them out, but a brand new virus could get into my inbox.  If I were to open the attachment, I could infect myself.

If you have a big file to give to someone, use a zip utility to make the file smaller, but don’t email the file unless the recipient asks that it be emailed.

TSPY=1.42

In a previous post, I mentioned that file attachments are something you should avoid.  There are times when they are unavoidable.  If you must attach a file to an email, Zip it first.

Zip is the generic term for “compress” with a compression program based on PKZip from a company called PKWare.  Not many people use the original PKZip any more.  There is WinZip and an assortment of free and shareware titles that most people now use.  An “unzip” utility is built into Windows, but you will need to install some software in order to create your own zipped files.  If you don’t want to spend any money, I recommend 7-zip.

Here is how I explain compression to my students.

Did you ever wonder why all orange juice is labelled 100% pure orange juice – from concentrate?  One gallon of OJ is approximately one half orange “stuff” and one half water.  In Florida, the water is removed.  One truck is used to drive the concentrate to Ohio.  In Ohio, the water is added and two truck loads of OJ (from concentrate) are profitted.  The savings is in the shipping.  It only took one truck to get two truck-loads-worth of OJ to Ohio.  With the price of fuel these days, that’s a lot of savings.

File compression “removes” redundencies in files that can be replicated later.  The process makes the file smaller for transport or long-term storage.  The compression process is complicated to understand (here is a good explanation), but the results are easy to comprehend and benefit from.  Compressing a file makes the file smaller.  Smaller files can be sent across the Internet faster.  This means it will take less time to send and to receive a compressed file.

Be aware that different kinds of files will compress with different efficiencies.  Some files (like Word documents) will compress down to 10% of the original size.  A picture in JPEG format may only compress to 95% of the original size.  Depending on the type of file you compress, your mileage may vary.

There is one other important benefit to compression.  All the zip utilities let you place multiple files into one zip “package”.  So instead of attaching twenty different pictures to an email, all twenty pictures can be placed inside one zip file.  The one zip file can be sent.  The recipient can unzip the file and get all twenty pictures.

That said, it is important to note that zipped files are only for transport and archiving.  To use the contents of a zip file, you must first unzip it.

TSPY=2.12

In my undergraduate days we used an editor affectionately named the “chainsaw editor”.   It didn’t have a spell checker.  It couldn’t create margins.  Most of the time it wouldn’t even save your work.  As a result, we re-typed a lot of things.

Today, most programs than can be used to create content have an “auto-save” feature.  Word has one:

http://support.microsoft.com/kb/107686

Even this web-based blog editor has one.

Auto-save will automatically save your work as you work even if you don’t do periodic saves as you create your project.  It can be very irritating to invest an hour only to have a crash or other problem (like a power outage) kill your project.  Auto-save can recover your work from the last auto-save point.

My rule of thumb is fifteen minutes.  I don’t mind re-doing something that takes five or ten minutes, but fifteen becomes a nuisance.  I set all my auto-saves to a fifteen minute save cycle. 

You may have to check the help files of the different programs you use, but most of them will have an auto-save feature.  Turn it on!  It can prove to be a real life saver.

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