As we have studied in Session 6, the WWW is a system to retrieve such various files required for a Web page as HTML files which are stored on a WWW server to display them on the Web Browser, isn’t it?

For the purpose of reviewing, the video clip is inserted below once again. So, please have a look.
（The video is hidden on this website.）

By the way, we created a simple HTML file in Session 6 and 7. This is a genuine Web page (a file for a Web page). The problem is that at this stage you can enjoy seeing it only on your PC. Of course you can copy the HTML file into a USB flash memory etc. and give it to a friend of yours so that the friend can see the page. Even in that case, however, only that particular friend can see the page and other people cannot.
Then, how can you make your page accessible to other people? To do that, as you have seen in the above Mechanism of how to display the Web page, you have to store your files on a Web Server so that they become accessible when required by the Web Browser on the Internet. In this way, you can publish the Web page you created.

Here, let us do some reviewing. Do you remember how to create a Web page? The following is the outline of it:

1. On your PC, create HTML files as well as files containing data such as images that are required for the Web page.
2. Store the various files that have been created in a designated folder on the Web Server.

Although what we have done is still at very beginning level, we went through step 1 above in two sessions. Then, what do we do in doing the other step, step 2? Actually this is the step to publish your Web page.

In other words, all you have to do to publish your Web page is “to store the various files for the Web page in a designated folder on the Web Server”. It’s easy, isn’t it?

Before storing the files for the Web page on the Web Server, there are a few things regarding the Web Server I want you to understand.。

Generally in the world of the Internet, “Server” means “a machine (computer) to offer services for a number of users (clients)”. The “services” here include all sorts of things we enjoy when we use the Internet, including delivering Email, offering a variety of files, and distributing videos.

Therefore “the Web Server” means “a machine (computer) to offer Web (WWW) service” among other servers. The Web (WWW) service means to send out the resource (file) requested by a Web Browser, a Web client, to the Web Browser (the computer where the Web Browser is operating).

Then what do you think the actual Web Server is? You might imagine it is a really large machine.

Actually the Web Server is basically no different from the PC you use. The only difference is that, as it is a machine simultaneously used by a large number of people, it is usually a machine which has a good processing capability and can store a large number of files. Therefore, it is possible to use your PC as a Web Server.

That means that there should be folders (directories) in the Web Server, and various files are stored there as well. Therefore, “to store the files for a Web page on the Web Server” simply means “to copy the files you created on your PC to a folder on the Web Server”.

Then how can you copy the files to the Web Server?

In case that you want to have a copy of your photo on your friend’s PC, you can either attach it to your email message and send it to the friend to let him or her to store it, or save it in a USB flash memory stick etc. and connect the device directly to your friend’s PC to copy it.

However, as the Web Server stores many Web pages for a number of people on just one machine, it is impossible for the administrator of the Web Server to pick up the files sent via email and put them in an appropriate folder.
It is not possible to use a USB flash memory stick to copy it either, as it is not possible for you to directly operate the Web Server.

For this reason, when you want to put a file on various servers including the Web Server, you should use a dedicated protocol for transferring a file via network. (A typical such protocol is called “FTP or File Transfer Protocol”).

However, for you to be able to use this protocol (function), this service must be available from the server. For this reason, the Web Server, in addition to offering those normal services as a Web Server, usually offers a service to transfer Web page related files to the Web Server.

In Information Processing Fundamentals, we transfer our files to the Web Server using SSHorSCP. (Although telnet or FTP is used in many cases, in Information Processing Fundamentals, we use SSH or SCP because of a security concern.)

(Note) In case of intranet etc, we also have an environment where you can use FTP. (Actually “Introduction to Information Technology A/B” which is offered to first-year students of the university, uses FTP Client.)

Let us check the terms in relation to file transfer here.

Transferring files on a PC (called a “client” as opposed to the “server”) to the server via a network is generally called “upload”.
On the other hand, fetching the files on the server to the PC via a network is called “download”.

A word similar to “upload” is “ 「update”. This word means “update the files etc.” and does not involve the server/client. For example, this word is used when “you replace defective software with a new corrected version” or “refresh the display loading a Web page which has been updated”.

For example, these terms are used as follows:

• As the assignment file was completed, I uploaded it to the WebCT server.
• I downloaded a free software file from the Web page.
• As some defects of the OS are announced, I downloaded a corrective software file and updated my PC’s OS.
• Iuploadedthe HTML file I created on the Hidemaru editor to the Web Server.
• “Please update the Web page by uploading the recent HTML file to the Web Server”.