Web content is delivered to the end user's browser as follows:
A user requests content stored at a particular URL. The URL comes from another page, an email message, even printed content. The web server for the hostname in question translates the URL into a path and filename based on its configuration. The relationship between directories is not always as simple as that described in the file and directory management section. As an example, the top level of our web server is stored in the directory /scp_1/web_root. The file named /scp_1/web_root/index.html can be requested using the URL http://scholar.lib.vt.edu/index.html. However, the URL http://scholar.lib.vt.edu/theses/index.html does not point to the file /scp_1/web_root/theses/index.html. Rather, the web server is configured to look for materials related to the /theses directory in /theses_1. So, the file is located at /theses_1/index.html instead. If the requested file must be parsed or executed (as in the case of server side includes and PHP), the web server parses or executes the file and delivers the content. If the server can't figure out where to find the requested file, a standard but customizable message is sent (something like "404: file not found"). The end user receives the content. If the content is a web page containing images, each image is loaded using the same process.
Your job as a web author is to create and place content on the web server such that it can be delivered to an end user when its URL is requested.
URL paths and filenames vs. system paths and filenames.
The most important thing you'll need to know before adding new content to a web server or editing existing content is how to translate a URL into a path and filename on the server (and vice versa). Here are a few examples of the settings for our current web servers.
URL system path http://scholar.lib.vt.edu/index.html /scp_1/web_root/index.html http://scholar.lib.vt.edu/theses/index.html /theses_1/index.html http://scholar.lib.vt.edu/ETD-db/index.html /export/ETD-db/web_root/index.html http://spec.lib.vt.edu/index.html /spec_1/web_root/index.html http://lumiere.lib.vt.edu/index.html /home/www/lumiere.lib.vt.edu/web_root/index.html http://etd.vt.edu/index.html /home/www/etd.vt.edu/web_root/index.html
Here is the overall view of the process of creating and updating web content:
Updating Existing Content Creating New Content Download a file from its current location using an FTP client such as Fetch or WS_FTP. Do not simply save the source from within your web browser, as this may break dynamic content (see the section on server side includes). Edit the content using a tool like BBedit for HTML files, or a tool like Photoshop for images. Create the content using one of the same tools. Transfer the updated content using an FTP client, overwriting the existing content. Transfer the new content to a desired location using an FTP client.
Now you should be ready to move on to the sections on HTML, and file and directory management.