Helpful tips for working with NJIT University Computing Systems for Homework and projects

Rafael Orta, Prashanth Sanagavarapu

and George Blank

Overview• The information presented here is not original content, it is

the result of gathering spread information around the NJIT web site and the power points slides in the professor web site; while I was doing my homework and project I wished this information would be in a single place rather than have to spend hours looking for it all around. That is why I decided to put together this compilation of information which I hope would make your life easier.

Rafael Orta• Rafael made a good start, so I decided to use his document as

my location for additional information on using the NJIT UCS systems. More detail is available in the lecture on the Andrew File System in the CS 633 course.

How do I get an UCS account?

• While most of the time when you register for this class a UCS and Oracle account is created for you, there are exceptions. So here is where you can get help when dealing with those exceptions. Fill this form and get your account.

https://mailsys.njit.edu/%7Eaccts/cgi-bin/new

• You can get additional information about University Computing Systems here.

http://ist.njit.edu/accounts/afs.php

Prepare your account for Web Hosting

• You need to set up your home page so the files in your account can be accessed through a browser. A home page and a sample index.html file are automatically created for you when you get a UCID. You can edit that index file or substitute a file of your own to link to your content. Files named index.html or menu.html are found automatically by browsers.

• Your homepage is located at http://web.njit.edu/~<UCID> Substitute your UCID for <UCID>, and do not forget the tilde (~).

How do I share files in AFS?This information is very helpful especially while working on a project as a groupLet’s assume you want to grant to user ro5 access to the directory project in your account, you type

$fs sa ~/project ro5 rwlFor detailed instructions and more information on AFS permissions please visit.

http://web.njit.edu/all_topics/AFS/ShareFiles/

Allowing an instructor to run files in your directory.

Professor Blank would like to have you grant him permission to read your project directories. User name is gblank.

$fs sa ~/project gblank rl

Two permissions are required: “read” and “look up” as specified above, which use the Open AFS fs command. There is no “execute” permission. OpenAFS allows any authorized users who have lookup permission to execute files where the execute permission is set for the user: -rwx------

How do I setup Tomcat

Tomcat 5.5 is already installed in AFS, all you have to do is configure your

account to be able to use it.

• Servlets and Java Server Pages can be served on web.njit.edu from a user's public_html directory.

• First make sure that your login directory is correctly set up for Web pages.

• Once your login directory is correctly set up, your login directory and public_html directory can be set up for Tomcat.

How do I setup Tomcat cont.

• /usr/ucs/bin/tomcat.setup configures your login directory and public_html directory to enable web.njit.edu to serve servlets and Java server pages.

• Explicit instructions regarding the Tomcat server are given when tomcat.setup is run.

• To run tomcat.setup, log in to your account on any AFS Unix client (e.g., afs1.njit.edu to afs36.njit.edu), and enter: tomcat.setup

How do I setup Tomcat? continued

Note: The Tomcat server restarts daily at approximately 6:00 AM. When you first set up Tomcat, your servlets will not become available until after the server completes the restart, which takes about 30 minutes. Additionally, certain changes to your WEB-INF directory will not become available until after the Tomcat server restarts. Most subsequent changes or new servlets with be found and executed immediately (no restart required).

More information can be found at: http://web.njit.edu/all_topics/Servers/Tomcat/

Security Requirement

• Off-campus access to AFS must use Secure Shell (ssh) over a Virtual Private Network (VPN).

• To download software (including regular VPN) you must use VPN. This is possible with webvpn. Go to http://webvpn.njit.edu or follow the instructions at http://telecom.njit.edu/vpn/WebVPNInstall.html

• Once you have a VPN connection, you can download the Secure Shell software at http://ist.njit.edu/software/index.php

Connect to UCS and Log In• Use the Secure

Shell Client and your UCID username and password to log on the one of the AFS machines, such as afs23.njit.edu:

Use Secure FTP• You can use

the Secure File Transfer Protocol program to upload your materials. The SSH Secure File Transfer Client is provided when you get SSH.

Use Secure FTP• The SSH FTP Client is a simple drag and drop

interface. Most students should have little trouble figuring it out.

• If you do have trouble, try the Help selection on the menu. If that does not work, post your problems on Web Board and I will add enough detail to this presentation to guide you through it.

NJIT University Computing Systems available to students

• There are 36 systems running Solaris available, afs1.njit.edu through afs36.njit.edu. If you are using Tomcat, please use afs31 through afs35.

• There are 29 systems running Linux at osl1.njit.edu through osl29.njit.edu.

• There are two Apache web servers available to run your home page from, web.njit.edu and harp.njit.edu. Please use harp if you have audio or video files.

• An Oracle database server is available at prophet.njit.edu.

Install Open AFS on your PC

• You can get a local Open AFS client on your desktop. This allows you to do things like open a file directly with Word or Eclipse from UCS and save it back without copying files back and forth.

• Full instructions are found at http://web.njit.edu . Select AFS, then AFS Windows Client from the menu on the left.

Ports available• Homework often requires you to specify ports to use

as a program entry point. It is often a bad idea to use the ports listed in the homework because other students are doing the same homework at the same time and the first one to take a port on a particular cpu blocks other users.

• Ports below 1024 have defined functions and are reserved. Some other ports are predefined, including 8080 for Tomcat, 7000 to 7032 and 7101 for Open AFS, and 1521 for Oracle.

• You can usually use most other ports from 1025 through 65535.

What if I need more space?

• Student teams needing more file space than they are allocated in their own accounts on OpenAFS for team projects can get a team project space created for them.

• Send a request to the professor indicating the amount of file space required. This will be forwarded with approval to sys@oak.njit.edu, and subsequent communication will be with the UCS system administrator.

Problems with applets?• Many students face problems while running

Applets from AFS .• some of the common Problems are…

• Applet Not initiated• Applet loading Failed• Source not found.

Problems with applet? (cont..)

• (Imaginary) messages from my mail box : Dear Prof, My applet works on my laptop but does not

work on web. Please grade my work through screen shot or I will show it class on my laptop.

• Prof Replies : Dear student, This course is “Java and the Web” not “Java on

Your Laptop.”

Failed Loading

The most common problem you see….

This means your applet failed!

Files in Same Folder?• Did you keep the class files and html document

containing the class file in same folder? • If you don’t have them in the same folder, it is harder

to write the code to get them to load. (It can be done.)

Ex :

Use single folder to store all related files as above

Backslash in URL

• One of the most common Error Messages is

Loading Applet Failed !!• Do you have a backslash \ instead of a / in your

URL? (Put mouse pointer over link, look at bottom of screen.)

correct form (bottom of browser):http://web.njit.edu/~sss49\java.htmwill work in IE on Windows, but not on other browsers, and will

not work on AFS or any Unix version.

Eclipse Setup

• When you see your applet running on Laptop and it doesn’t run on the Web, especially if

you are using Eclipse, declare all the classes in the default package. Do not use a package name.

Runningapplet will work on web

This HelloWorld Applet is harder to transfer to Web

Small changes in file names

• Another common mistake is to use different case for the class name in your html code.

Ex: If HelloWorld.Class is the class file and you misprint it as Helloworld.class in html code then applet can not find the source and fails to run.

Check the “W”

HelloWorld, Helloworld, and helloworld are three different names toUnix and most browsers, although they are the same name to Windowsand Internet Exploder.

References

• http://web.njit.edu/all_topics/AFS/ShareFiles/• http://ist.njit.edu/webhosting/public_html.php• http://ist.njit.edu/webhosting/index.php• http://ist.njit.edu/accounts/afs.php• http://ist.njit.edu/webhosting/step_by_step.php• http://web.njit.edu/all_topics/Servers/Tomcat/• http://web.njit.edu/• http://web.njit.edu/~gblank/