Exercises, examples and other material relating to training module A207. This topic is presented on public courses Deploying LAMP - Linux, Apache, MySQL, Perl/PHP, Linux Web Server, Deploying Java Applications on Linux / Unix

HTTP (Hypertext Transfer Protocol) is used to transfer information between a web server and a web client. While you're using flat HTML pages you don't need to know much about the protocol, but once you get into web-based applications, a little knowledge can be a great help.

Articles and tips on this subject		updated
3432	3 digit HTTP status codes - what are they, which are most common, which should be a concern? We often talk during web related course / course modules about the status codes that are returned by servers - but I don't think I've ever written up a (near?) complete list. They are all three digit codes, and they're grouped by hundreds - so 200 series code are success, 400 codes are requests that ...	2011-09-11
2918	Downloading a report from the web for further local analysis There are many applications where users want to use a piece of web based software to explore data sets - to research information and come up with tables of results and lists of data which they then want to examine in more detail - explore further. How do they do that further exploration - perhaps through ...	2010-08-20
2738	What is all this SESSION stuff about? (PHP) If you're booking an airline flight online, you'll be taken through a series of screens to select route, dates, times, passengers, seats, then to enter payment details, and perhaps visa / government information too. It would be impractical to do the whole job on a single page, as you need the intermediate ...	2010-05-14
2596	Http protocol - what does a web server send Question - what information do you send using http protocol from a web server? 1. HTML (e.g. .html) 2. Images (e.g. .jpg, .gif, .png) 3. Icons (e.g. .ico) 4. Style Sheets (e.g. .css) 5. Java Scripts (e.g. .js) 6. Applets (e.g. .class) 7. Video (e.g. .rm, .mpg, .mp4) 8. Sound (e.g. .mp3) 9. Flash (e.g. ...	2010-01-24
2321	Uploading and Downloading files - changing names (Perl and PHP) When you are uploading a file to a server via http (in Perl or PHP), where is the file saved, and what is it called? And when you download a file, where is it saved on your local disc, and what name is it given? These are not unusual questions, but it can be hard to find the answer, as I was reminded ...	2009-08-04
1549	http, https and ajp - comparison and choice In a web scenario, client to server traffic is usually carried using an http (HyperText Transfer Protocol) transport. That's both from browser to public facing server, but also in ongoing transfers from the public facing server to other servers which provide content or run business logic in many applications. But ...	2008-02-23 (longer)
1503	Web page (http) error status 405 Running his first Java Servlet today, one of my delegates reported an HTTP status 405 from his code when he tried to browse to it. A new one on me ... I am used to a good number of other return codes, but hadn't seen this before. It turns out that the cause was the lack of an appropriate doGet method ...	2008-01-14
1378	Etag in http headers - what is it? If you've ever looked at the headers you receive back from your web server, you may have noticed an Etag. What is it? An Etag is an "entity tag" and it provides a unique identifier for the resource being supplied. Browser requests can use an etag and an if-match header to check whether a resource ...	2007-10-03 (short)
484	Setting the file name for a downloaded document When you're writing a script to send a file to a browser, you can force it to be saved as a file using a content type header, and you can give it a name different to your script by using a content disposistion. In PHP, you might write header("content-type: application/octet-stream\n". "content-disposition: ...	2006-06-05 (short)

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