7.5 Exercises

Exercise 7.1

Use your web browser to examine the actual HTML code for some of your favorite web pages. For example, on my Netscape browser, once a page is displayed, I can select the menu options View and then Page Source to see the HTML code.

Exercise 7.2

Identify the web server that is running on your computer. What version of the software is installed? Find the documentation for that web server. Are there good books available for that web server; free online tutorials, newsgroups, or FAQs; or local experts? Locate and examine the various logs for your web server. Where are the configuration files? How do you stop the web server, change a configuration file, and start the web server again? Is it a good idea to make a copy of a working configuration file before you change it?

Exercise 7.3

Is your computer located behind a firewall or a proxy server?

Exercise 7.4

Get the URL::URI module and read the documentation.

Exercise 7.5

Read the CGI module documentation. If available, look at a book about Perl and CGI.

Exercise 7.6

The sequence file uploaded by the CGI Perl script webrebase1 is assumed to be in FASTA format. Rewrite the program so that it uses the SeqFileIO.pm module and reports a problem back to the web page if that module can't determine the sequence file format.

Exercise 7.7

Write a new version of the CGI script webrebase1 that uses the RestrictDB.pm module instead of the Restrict.pm module; it will use a relational database store of Rebase information instead of a DBM hash-based store. Note that your DBMS will have to allow the web server to access its Rebase tables; this may occur as the user nobody or some other. Getting the permissions right is probably the hardest part of this exercise and is very much dependant on your operating system and web-server software.

Exercise 7.8

Write a web-based CGI Perl program that provides some information about your lab or an experiment that you've conducted. Include a means whereby users can send you email with questions.