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D. Tips for creating and editing web-based presentations

Although MS FrontPage is widely used for creating web content, Microsoft has loaded it with features that can generate web pages that work with Internet Explorer, but may not work with other browsers. For example, FrontPage creates web pages that do not conform to standard HTML. As well, it also uses a proprietary Microsoft character set, so that some characters will not appear normally in non-Microsoft browsers such as Firefox or Safari.  DreamWeaver is probably a good choice if you want a commercial package.

A good free alternative is the Seamonkey composer, which is part of Mozilla SeaMonkey.
http://www.mozilla.org/projects/seamonkey/. It is probably the easiest way to make web pages.

Tutorials on Creating Web pages using Seamonkey Composer
http://www.rochesterschools.com/web/composer/default.htm
http://groups.lis.illinois.edu/itdweb/SeaMonkeyTutorial/SeaMonkey/index.html

1. Visual organization

Perhaps the most important point in creating web-based presentations is that the visual layout should help the viewer understand the organization of topics. At the same time, the web presentation must be flexible enough to communicate in two different ways: as a real time presentation, and for casual reading in a web browser.

For the purposes of presentation, use visual components that catch the eye, such as large main headings and smaller subheadings. Make headings a different color than text. Bullet points and indentation also help to show how the information is organized.

For the purposes of reading, you can include text in a smaller font, that is not intended to be read during the presentation.

2. Capturing and creating graphics

Images can be saved from remote Web pages, or captured directly from the screen. Most web browsers can display images from files in PNG (*.png),  GIF (*.gif) or JPEG (.jpg) formats.

3. Text and images must be readable by people in the back of the room

Putting up text and graphics that your viewers can't see or read accomplishes nothing.  Again, make sure headings, subheadings, and tables are readable on the screen. For some reason, the Ariel/Helvetica family of fonts seem to be more readable, from a distance, than fonts such as Times.

Another consideration is contrast. Text should contrast strongly with the background. Although it may look cool, a dark blue text against a black background is virtually unreadable. Use bright  text against a dark background, or dark text against a bright background.

dark text,
dark background
dark text,
bright background
bright text,
dark background
bright text,
bright background

You can barely read this.


This is best both for viewing and printing.

This looks great on the screen or monitor, but is not so good for printing.


This isn't very good either.

4. Keeping text with graphics

When you want to keep a block of text with a graphic image, it is best to embed both in a table. For example, the text in this paragraph, and the window to the right, are in separate columns of a table with 1 row. The Insert Table window shown is the actual window used to create this table, in the web page you are reading now.

 Usually, a table with 1 row and 2 columns works well. If you set the border to 0 pixels, it will not even look like a table, but rather, like an image that is set to wrap text to the left.

Notice that you can even insert a caption by inserting text below the image.

Settings for creating a table that keeps text with graphics.

Q: When I look at my web page in the web browser, it doesn't appear. Instead there is an empty box.

A: In the SeaMonkey Composer, double click on the image, which will bring up and Image Properties window for your image.  Under the heading Image Location you can see the URL for the image. It is possible that the name was spelled incorrectly. But another possibility is that SeaMonkey inserted a fully qualified file path to the file, rather than just the name of the file:
WRONG: file:///home/plants/frist/courses/bioinformatics/lec02/mozilla.insert_table.png
RIGHT: mozilla.insert_table.png

The fully qualified path will only work if you open the HTML file using File --> Open. When you navigate to the page through the web server, there will be no file at that exact file path, so you get a file not found error.


5. Relative links versus absolute links

There are two kinds of hypertext links:
Wherever possible, use relative links. This is important, because at a later time you may reorganize your directory structure, or even copy and re-use web directories for other purposes. Relative links should not need to be changed, in most cases. Usually, the only time you need absolute links is for pointing to external web sites.

6. Organize your web files in a hierarchical directory tree

Organization is everything. Your web files should be organized in a directory tree that reflects the relationships between web pages. Often, there is a master page which has links to many other pages. The master page would be in a high-level directory, and there would be a subdirectory for each of the other pages. Most importantly, all graphics files for a given page are kept in the same directory as the page that displays them. This means that you can use relative links for everything, and that the relative links will only need the filename, and no path.

The PLNT7690 directory, shown at the beginning of section C,  illustrates this point.

7. Use fixed fonts for program output

Many programs generate output that only makes sense with a fixed font.  Most fonts commonly-seen in documents are proportional fonts, meaning that narrow letters such as 'i' or 'l' take up very little width, whereas wide letters such as 'O' take up more space. In fixed fonts, all letter and numbers take up exactly the same width on a line of text. For example, output from the BACHREST program, listing restriction cutting sites and restriction fragments for a sequence cut with the enzyme AcoI, are shown in both fixed and proportional fonts. Make sure that when output is shown on a web page, it is in a fixed font.

fixed font
                                         # of
Enzyme          Recognition Sequence     Sites     Sites   Frags   Begin     End
------------------------------------------------------------------------------
AcoI            Y^CCGGR                      3

                                                    1289    2817    2533    5349
                                                    1556    1288       1    1288
                                                    2533     977    1556    2532
                                                             267    1289    1555

proportional font
AcoI            Y^CCGGR                      3
                                                    1289    2817    2533    5349
                                                    1556    1288       1    1288
                                                    2533     977    1556    2532
                                                             267    1289    1555


Most fonts are proportional, eg. Helvetica, Times.

Examples of fixed fonts include Courier, Lucida typewriter and Terminal.

E. Remote connection to your Unix account

1. Remote text-based connection - ssh

Public key encryption
Public key encryption is a mechanism for sending messages that can only be encrypted by the recipient, and no one else. A pair of numbers, called a Public Key and a Private Key, can be generated using one of several methods. The most important point is that any message encrypted using the Public Key can only be decrypted using the Private Key. To make it possible for others to send you encrypted messages, you make your Public Key available, for example, on your web site. However, your Private Key is kept secret.

For example, if Bob wants to send Alice an encrypted message, he reads Alice's Public Key and encrypts the message. Next, he sends the encrypted message to Alice, who can decode it using her Private Key. Even if the encrypted message is intercepted by someone else, they can not read it.

For more on Public key encryption see
http://en.wikipedia.org/wiki/Public-key_cryptography


SSH - secure shell
SSH is a program that uses public key encryption to let you run a text-based session on a remote server. SSH automatically generates a Public Key/Private Key pair, so the user doesn't have to know how to do that.

There are actually three related programs:

Program
Function
ssh
run a remote shell
scp
copy files to remote server
sftp
transfer files to remote server

Connecting to Unix from another Unix machine

Any Unix or Linux host will have ssh as a standard part of the installed software. To connect to the U. of M. Unix system, from another Unix host type:

ssh -l userid ccu.umanitoba.ca

where userid is your unix userid. You will be prompted for you Unix password. If the password is correct, you will see the command line prompt appear. When you are done, simply type 'logout' to end your session.

The Windows DOS command line doesn't include an SSH command.On Windows, you need to download a program that will run a terminal session. See
Running a comandline session from a Windows PC

2. Remote desktop session - VNC

3. Thinlinc Client


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Lecture 2, part 3 of 3
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