B211 Lab Week 4 (1)

Laboratory Week 4 part I - Plug-ins, Helper Applications and Cookies

Learning Objectives:

Understand how the settings for plug-ins and helper applications are made using Netscape Navigator and Microsoft Internet Explorer.

Understand how the settings for cookies are made using Netscape Navigator and Microsoft Internet Explorer.

Before doing the tutorial, please read:

Topic 2 lectures "What in the world is the World Wide Web?" and "Internals of the Web Client".

Software required:

This lab sheet only requires the use of Netscape Navigator and/or Microsoft Internet Explorer (MSIE) browsers. External students having only one of those browsers, can just do the exercises for one of them. The concepts for the other browser is similar.

The instructions are based on their menu items according to Navigator version 4.x and MSIE version 5. If you have other versions of the browsers, the menu items may not be exactly the same, but should not be completely different.

Instructions:

Settings for Plug-ins and Helper Applications in Netscape Navigator and Internet Explorer (IE)

For Netscape Navigator, the list of installed plug-ins and helper applications are found in menu item Edit>Preferences>Category:Navigator>Applications. Have a look through the list, and see the settings for various common file like Hypertext Markup Language (HTML), GIF, JPEG, Acrobat (PDF), etc. Note that all of them have 3 items defined:

Extension - the extension of the file name (eg. .pdf, .html, .gif, etc).

MIME type - the label used by HTTP to identify this file format.

Handled by - which program is suppose to handle this type - could be Netscape Navigator itself, a plug-in, or an external helper application.

For MSIE, the list of installed plug-ins and helper applications are hidden from the user. MSIE loads the plug-ins in the following order:

Download all plug-ins specified in the Windows Registry key

HKey_Local_Machine\Software\Microsoft\Internet Explorer\Plugins

The windows registry is how MS-Windows keeps system configuration information. You can look at Windows Registry key values by executing the regedit program (click on Start>Run menu item on your MS-Windows desktop, and type "regedit".

Searches the MSIE plug-ins folder for installed .DLL (dynamic link library) files. These are typically located in the C:\>Program Files\Internet Explorer\Plugins folder.

Searches the Netscape Navigator Plug-ins folder for installed .DLL files. By default, this is the C:\>Program Files\Netscape\Navigator\Program\Plugins folder.

Settings for cookies in Netscape Navigator and Internet Explorer (IE)

For Netscape Navigator, the settings for handling cookies can be found in menu item Edit>Preferences>Category:Advanced>. For Internet Explorer, the same can be found in Tools>Internet Options>Security>Custom Level>Cookies. Have a look at the few possible settings.

Browsers puts the cookie information into files. The location of the file depends to whoever is logged in at the time. For Netscape Navigator, the file is in the directory in C:\>Program Files\Netscape\Users\username\cookies.txt - where username is the login name of the user logged in at the time. MSIEr puts cookies from separate web servers by separate users into separate files. They are in C:\>Windows\Cookies or C:\>WinNT\Cookies. Use Notepad to have a look at the contents of your own cookie files. They may be empty if you have never used Navigator or MSIE on that particular machine to make requests to a web server that needs to download a cookie to your machine.

Exercises (for students with home machines only):

The following exercises requires you to make configuration changes to your browsers. This will not be possible using the machines in the internal labs. External students and other students with a personal computer at home may try those specific exercises. Students using internal labs should still step through the procedures as far as possible to gain an understanding of what is required.

Settings for Plug-ins and Helper Applications in Netscape Navigator:

Add a new file-type in Navigator and define the helper application to handle it. Select the menu item Edit>Preferences>Category:Navigator>Applications, click on New Type.Type the following:

Description of Type: B211 format
File extension: b211
MIME type:
Application to use:

Leave "MIME type" blank. For "Application to use", use the "Browse" button to select the notepad program, probably in C:\Windows or C:\WinNT. Click OK for all the dialog boxes and go back to the Navigator main window. Now access the URL http://www.it.murdoch.edu.au/units/b211/labs/test.b211. The file is really a HTML file. Does Navigator invoke Notepad to open the file?

Change the setting in (1) so that it MS-WORD instead of Notepad. In Navigator, select the menu item Edit>Preferences>Category:Navigator>Applications, click on Edit. Use the "Browse" button for the "Application to use" to replace Notepad with MS-WORD. MS-WORD is probably in C:\Program Files\Microsoft Office\. Access the file with .b211 extension again. Which applications gets called this time?

Repeat the last step and replace MS-WORD with MS-EXCEL.

Unfortunately, changing the plug-in settings for MSIE is not as easy. It involves changing the file association for the operating system. If you are familiar with Microsoft Windows, you may already know how to do this. We will not go through it in this lab (or this unit).

Settings for cookies in Netscape Navigator and Internet Explorer (IE)

Using Navigator, change the cookie settings so that it warns you when you are about to receive cookies. Go to http://www.amazon.com/, where the web server does try to download a cookie to your machine when you access the site. What warning do you get?

Give permission to the browser to save the cookie. Now check your cookie file and see if you can spot where the new cookie information is.

Repeat (1) and (2) using MSIE.

Remember to read the week's development on the Internet by scanning through relevant articles in the IT section of Tuesday's the Australian newspaper - use the online version or the physical copy in the University library. Get into the habit of keeping up with current developments. Test your knowledge of major developments by going through the Good News Week self-tests.

H.L. Hiew
Unit Coordinator