1. © De Montfort University, 20011 Web Servers Chris Hand And Howell Istance De Montfort University

2. © De Montfort University, 20012 Web Serving Web servers Configuration File Structure / Mapping / Practicalities Logging, Administration etc.

3. © De Montfort University, 20013 Web Servers Web server functionality: –process requests (GET / POST …) –deliver content (HTML files, whatever…) –log activity (where/ when/ what/ …) –authentication(secures parts of the site) –Run databases, secure encryption, caching software, logs analysis …

4. © De Montfort University, 20014 Server OS There are two main battlegrounds –Windows NT4/5 with Microsoft’s IIS (Internet Information Server –Unix machines with Apache –Unix or NT with IBM or Netscape servers 3 main deciding factors –Staff capability –Policy (tied to IBM/Microsoft/Netscape) –Cost

5. © De Montfort University, 20015 System Choice – Pay Microsoft –Excellent Office support built in –Excellent DB integration –ASP – easy to use/ maintain –Proprietary Netscape / IBM / iPlanet –Alternatives to MS –Similar features –Using more open standards

6. © De Montfort University, 20016 System Choice – Free Apache Low cost Rapid open development Well supported Cross platform Secure Flexible www.netcraft.com/survey

7. © De Montfort University, 20017 System Choice – Hardware 1 Memory – most important CPU – fast often helps –Fast when doing speciality serving i.e. RealVideo … –Fast for very large databases –Fast for a large number of users –Minimum: Pentium II 266 Mhz –Needed: Dual; Processor Pentium III Multi-servers to share the load/ reliability

8. © De Montfort University, 20018 System Choice – Hardware 2 Bandwidth –Ideally, as much as possible –Don’t share with other tasks Connection –Uptime is very important –Hosted service - we only create content –Self-hosted - need network admins too

9. © De Montfort University, 20019 Servers: Apache Open Source, multi-platform Evolution of the NCSA server (1994/5) 1 year later = #1 server in the world Still leader (Sept ‘01: 58% of market) Very stable Masses of features Extensible Not easy to configure, but powerful

10. © De Montfort University, 200110 Servers: IIS Big player – produced by Microsoft IIS 5.0 part of Windows 2000 Advanced Server, not the standard server Windows Media Server is an installable component part of IIS5.0 Supports.cgi but also Internet Server Application Programming Interface – applications written with this API, as.dll and loaded into the address space of the HTTP server Supports.asp (Active Server Pages)

11. © De Montfort University, 200111 Servers: Jigsaw The W3C reference server Written in Java Experimental Flexible for testing Runs on anything Good support for servlets and JSP

12. © De Montfort University, 200112 Server Configuration Common configuration info –Port to run on (listen on) –Root directory location in local filesystem –Administrator contact / error handling –file to MIME-type associations –URL Redirection –Directory browsing configurations –Authentication / passwords –/robots.txt –Logging –Virtual hosting

13. © De Montfort University, 200113 Configuration Port to run on (listen on) –Usually port 80, in theory can be anything > 1024 –Lets us run multiple servers on different ports Server Administrator contact –An email address –A feedback form –Replacement page for errors like 404 –An automatic tool to inform the admin

14. © De Montfort University, 200114 Configuration: Redirection Browser requests URL, server sends it somewhere else –on same server –on another server Useful when content has moved –send browser to new location automatically

15. © De Montfort University, 200115 MIME Multi-purpose Internet Mail Extensions File extensions are not reliable as a means of identifying type of content, different operating systems use different conventions General form: Content-type: type/subtype –text/html –text/plain –image/gif –application/postscript –video/x-ms-wm x- prefix to subtype indicates ‘experimental’ MIME type

16. © De Montfort University, 200116 Configuration: MIME video/mpegmpeg mpg mpe text/htmlhtml htm text/plainasc txt model/vrmlwrl vrml image/gifgif image/jpegjpeg jpg jpe Each MIME type tells the server what content type to send back for a particular file extension

17. © De Montfort University, 200117 Admin: Server Logs Server keeps log files to record activity –access log - who requested what –error log - pages not found, scripts not working etc. Often become very large very quickly - rotation

18. © De Montfort University, 200118 Admin: server logs Log analysis –Top hits (month/week/day/hour) –Typical search words used –Main referrers –Top hosts – who/where –Top user agents (IE/NS/Opera) off-the-shelf packages available (e.g. analog) -- often provided with hosted service