Wednesday, July 11, 2012

Here's the page from yesterday:


http://pages.uoregon.edu/christie/110/notBlank.html


I want to go through how to get pages on the Internet.  Let's play with FTP!




It's time to take a little detour on the information superhighway.

Remember the hierarchy?  Remember the labels and relationships?  Well, it turns out that those are going to be *really* important to us.  

The World Wide Web is actually a hierarchy, when you think about it.  We start at the mother of all folders...the server.  For us, we're going to pretend our "root" is the server, even though it's really just the root of *our* particular website.  This means, in the future, when I talk about the folder under root/110, what I really mean is http://pages.uoregon.edu/yourName/110. Capiche?

If our root is http://pages.uoregon.edu/yourName, then what does the rest of the hierarchy look like?  What if I want to have root/110/images/pic1.gif?  How about root/110/p2/me.html?

You should be able to see something forming here.  I'm giving you a URL and asking you to derive what the Web hierarchy looks like.  Similarly, I can give you a path through the tree and ask you to turn it in to a URL.  It works both ways!

Now, imagine that the file structure on your computer is a hierarchy, too.  How do you know where your files are stored?  

What if we are already in a folder and want to access another file inside that same folder...do we need to go back to the root first?  No.  We *can* address locations according to our relative position to the file.  That is called "relative addressing".  When we send a browser back to the root and make it traverse all of the nodes again, that's called "absolute addressing".  

Let's take all of this knowledge over to the File Transfer Window.  

Open Filezilla and take a look at the two directory structures - your computer on the left and the server on the right.  Do you see the hierarchies?

Okay, now that we're back to Filezilla, there's one more thing that's going to be REALLY important.  Sometimes, you'll create a folder...then put something in it...and you won't be able to see it on the web. Often it is because you are "denied acces".

When you create files on the server, they are automatically given a combination of permissions. The choices are read, write, and execute.  Each of those permissions are set for three different types of user: owner, group and public.  That creates issues when your files get created so that even the owner can't write to it...or when the public can't execute your scripts!

We'll be setting our folders to 755 (keep this number in mind for later).  Now we're ready to get our files up on the World Wide Web!