First you will try using a screen scraper to access the NNPREDICT secondary structure prediction server. NNPREDICT (http://www.cmpharm.ucsf.edu/~nomi/nnpredict.html) is a nice example because it runs quickly and the HTML is very simple.
Unfortunately the original server is no longer available. Consequently, I have created a pretend version which does a dummy prediction but uses exactly the same formatting. You can try the web page and download the Perl screenscraper. Note that this dummy version does not do a real secondary structure prediction - it returns a random prediction but everything is in the same format as the original NNPREDICT.
First try out the server. Enter a protein sequence (a random series of letters will do) and observe the results. Also make a note of the URL.
Once you have tried the server, you need to record the information about the form on the web page. Take a look at the HTML source code for the page:
<html><head> <title>nnpredict input form</title> </head> <body bgcolor="F2F2F2"> <H1 align=center>NNPREDICT<br>Protein Secondary Structure Prediction</H1> <H2 align=center><IMG SRC="protein.gif"></H2> <H3 align=center>Enter a protein sequence and nnpredict will predict the secondary structure.</H3> <H3 align=center><a href="http://www.cmpharm.ucsf.edu/~nomi/nnpredict-instrucs.html">Click here for instructions</a></H3> <HR> <form method="POST" action="./nnpredict.cgi"> <b>Tertiary structure class:</b> <input TYPE="radio" NAME="option" VALUE="none" CHECKED> none <input TYPE="radio" NAME="option" VALUE="all-alpha"> all-alpha <input TYPE="radio" NAME="option" VALUE="all-beta"> all-beta <input TYPE="radio" NAME="option" VALUE="alpha/beta"> alpha/beta <dl> <dt><b>Name of sequence</b> (optional) <dd><input name="name" size="70"> <p> <dt><b>Sequence</b> <dd><i>(Use single-letter amino acid codes or three-letter codes separated by spaces)</i><br> <textarea name="text" rows=14 cols=70></textarea> <p> <dd><input type="submit" value="Submit"> <input type="reset" value="Clear"> </dl> </form> <hr> <b>Other Local Homes</b><p> <a href="http://www.cmpharm.ucsf.edu/cohen.html">Cohen Group Home</a> * <a href="http://www.cmpharm.ucsf.edu/">Cohen Group Welcome </a> <br> <a href="http://www.pharm.ucsf.edu/">Department of Pharmaceutical Chemistry Home</a> * <a href="http://www.ucsf.edu/">UCSF Home</a> <hr> <em>nnpredict was written by Donald Kneller<br> Copyright (C) 1991 Regents of the University of California <p>Web interface by <a href=http://www.fruitfly.org/~nomi/>Nomi Harris</a> (nomi@cgl.ucsf.edu, <A HREF="mailto:nlharris@lbl.gov">nlharris@lbl.gov</a>) <P> (Mon Feb 5 15:32:54 1996) </body> </html>
Record the following information:
You should have obtained: