In the last section, we studied how to identify a file in a virtual world which models the WWW Server. We studied that we cannot identify the file by just specifying the file name, after that we studied the absolute reference and relative reference as a means of dealing with that problem.

Actually, we can identify the file on the actual WWW Server in the same way as we do that in the virtual world.

The following are the sample image of the virtual world and the image of file/folder structure on a WWW Server which has exactly the same composition as the virtual world. The virtual world is shown on the left and the composition of the WWW Server in the real world is shown on the right.

There are four layers of rooms in the virtual world (image on the left) and four layers of folders in the image modeling the real world (image on the right). They have the same 4 layers. Please check the name of the room and the name of the folder on each layer to confirm that they correspond to each other. (Although the root directory is omitted in the virtual world, you know what it is, don't you?)
Please also check the items in each room and the composition of the room(s) immediately under each room to confirm that they are exactly the same as the files in each folder and the composition of the folder(s) immediately under each folder.

At this stage, perhaps you have noticed that there is an important difference in the way these two worlds are visualized. If there are people who have difficulty in seeing the correspondence between these two images, the reason might be the difference mentioned above. Therefore, I would like to talk about this difference from now on.

The difference is found between the position of the items and the room in the virtual world and the position of files and folders in the real world model.

For example, please look at the soft ice cream t0.html (/public_html/w05/test/t0.html) in the virtual world. This soft ice cream is located "in a room called test". However, in the real world model (image on the right), the "light blue t0.html" is shown not "in the test folder" but "under the test folder". Actually the file t0.html is "stored in the test folder" the same way as in the virtual world.

For this reason, it would have been impossible for some people to understand that files and folders are stored in a folder on the actual server (real world).

Now, let us look at another room (folder). Please take a look at the inside of the public_html room in the virtual world model on the left. You can see that there are ex1.html (cake) and entrances to the two rooms (w04 and w05), can't you? In the real world model on the right, a file called ex1.html and two folders called w04 and w05 are shown under the public_html folder. As explained above, with the real world model, "things shown under a folder are stored in that folder". Therefore, there are a file called ex1.html and two folders called w04 and w05 in public_html. Certainly w04 and w05 folders are contained in the public_html folder conceptually, so please train yourself so that you can see such relationship.

However, actually only the entrances to the w04 and w05 folders are contained in the public_html folder in the same manner as in the virtual world. The fact of the matter is that w04 and w05 are stored elsewhere. This is the reason why the public_html folder can contain a limitless amount of files. In other words, you can store as many files as you'd like, regardless of the size of the area allocated for the public_html (space of the room), so long as it does not exceed the hardware limit. (Haven't you thought that you cannot store a lot of files in a folder created inside a folder?)

Up to this point, the folder structure of the WWW Server has been explained in terms of both the virtual world and the real world. However, the real world model (on the right) is actually a "virtual expression" in which the actual folder composition on the server is shown in a simplified diagram, whereas the image which we called "the image of virtual world (where Kumataro is)" is much closer to the real relationship between files and folders. The image showing the folder composition on the server or on your PC is usually given in "a real world model". Therefore, whenever you come across one of these diagrams, you should recall the "virtual world (where Kumataro is)" and visualize the situation of how files and folders are stored to help you make reference to (identify) the file.