TECHNICAL INFORMATION

HARDWARE

SOFTWARE

• The WWW (httpd) server is The CERN v3 server. This was an early web server but is free, very stable and is fast enough for the load it supports...
• The mail server is the excellent EXIM mail program. As well as being free, this is easy to configure and offers many very powerful features.
• Mail access for club members is provided by POP3 and IMAP4 servers written by the University of Washington. Again, these are free and work extremely well.
• SAMBA is also used to make files available to club members using standard Microsoft Windows PC's. This excellent free software allows a Unix workstation to act like a 'Windows for Workgroups' server.
• The 'aerial.org' domain namespace is managed by the IN.NAMED server which comes bundled with the Solaris Operating System.
• The "clever" bits of the site are programmed 'in house' by the club webmaster. Several languages are used which include the following...
  • CSH and AWK (scripting languages that come bundled with Unix)
  • C (compiled using the free GCC compiler)
  • Javascript (for client side code that runs on most browsers)

DYNAMIC ROUTINES

• The homepage can be delivered in a number of different languages. The language is automatically chosen depending on the language preference of the requesting client. The links on the pages are then also modified to link to the pages and scripts using the appropriate language.
• The homepage contains 4 photographs which are chosen randomly. However the choice of these pictures is weighted depending on the link that was used to access the site. (For example, if a user arrives at the site having searched for 'parachuting' on a search engine then the photographs will be biased towards parachuting).
• Every request of the homepage and several other pages, such as each photograph, causes log data to be sent to a named pipe. Another low priority background process continually waits for this log data to arrive and then reads each entry when it does. It processes the entry by updating a number of statistical tables. This method ensures all tables are updated synchronously.
• A cookie is used to store the date that a given browser is used to access the site. If this browser accesses the site again at a later date then a link is automatically generated on the homepage to a program that calculates all the pages and pictures that have been added or updated since the previous access.
• The gallery is automatically generated on each request from a database of pictures. The surrounding text on the page is also added from a seperate file which depends on the required language.
• The program to display a photograph automatically detects if a 'low source' and/or a 'high resolution' version of the picture exists. If so, then the appropriate links and information are automatically generated. The program also detects if there is a web page that is related to the picture and also generates a link to that if so. The layout is also changed depending on whether the user is inside the frames environment or not. Also if the user is viewing a slideshow, then the next picture is requested automatically.
• The frames environment is created automatically by a program. This means that the main frame to appear when the frames environment is initialised can be specified as an argument in the link to this program. Like the homepage, this 'frames' program also looks at the language preference of the requesting client and loads the appropriate frames into the environment accordingly.
• Another program allows a user to add their email address to the club news email list. This program (with the help of Exim) checks that the email address is valid before adding it to the list. It then sends a welcome email to the specified address.
• When a message is sent to the news distribution list, a copy gets sent to a program that displays the message on a web page.
• Several programs have been written which allow club members to see various 'up to date' web site statistics via a web page. The displayed statistics are generated from the data produced by other programs (described previously).
• Javascript is also used on many pages for various reasons. These include generating dynamic buttons (on the menu frame) which light up and also to automatically download the frames environment if ever a page is requested by a browser without having loaded the environment (eg. by following a link from an external site). Even this page uses this routine! The slideshow in the gallery also uses Javascript to display the countdown.