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Tarantella instantly web-enables applications, delivering them to users through a familiar web browser interface. The three-tier architecture of Tarantella means that no changes are required to the users' client devices, or to the application servers hosting the applications.
All administrative updates are managed centrally on Tarantella servers, by designated Tarantella Administrators. Without visiting either the application servers or the client devices, Administrators can publish applications to users and make them immediately available for use. Administration uses the directory service model, with objects representing people and resources within your organization, arranged in a hierarchy that mirrors the structure of your organization.
Each user has their own webtop: their "application launchpad". The webtop travels with the user -- it doesn't remain with the client device. Users can access their own personalized webtop from any client device with a network connection to the Tarantella server.
Applications run on servers, not on client devices, and can be made resumable: this means that users can log out of their webtop without exiting the application. Later, they can resume the same application from any client device, and pick up where they left off. The applications keep running: users can start a lengthy calculation, log out of Tarantella, travel to their destination, and then resume the application to find the results waiting for them.
For scalability and load balancing, Tarantella servers can be grouped into an array: sharing the same information about users, applications, and usage information, effectively acting as one, larger, server.
Tarantella helps users meet their goals seamlessly, and makes administration easy.
Users can log in to Tarantella in two ways:
http://host/tarantella/cgi-bin/install.cgi URL
(where host is the name of a host on which Tarantella is installed).You can publicize a single URL to users (whether they use a web
browser or the Native Client), of the form
http://host/tarantella.
If you use a secure web server, you can give users an https URL.
In a web browser, opening this URL shows a Tarantella splash screen, followed by a login page where users can type their username and password for the Tarantella server. Depending on the browser, users may be asked to install the Tarantella Java archive on their client device. We recommend they do, for best performance. This archive updates automatically when the Tarantella server is upgraded.
In the Native Client, users type the URL together with their username and password for the Tarantella server.
Tarantella has a flexible authentication mechanism, allowing different user types to log in to Tarantella in different ways.
By default, Tarantella is configured to allow users with an account on the UNIX host to log in with their UNIX username and password. All UNIX users see the same webtop.
You can also allow users access to Tarantella if they have been authenticated by:
Alternatively you can allow anonymous webtop access to a "kiosk"-style webtop.
Some users, called Tarantella Administrators, are allowed to configure Tarantella. These users are like the UNIX root user - they can change any part of Tarantella they want to. Tarantella Administrators can use the Object Manager administration tool to create objects for people in your organization, customize the webtop for each person, and easily configure who is allowed to log in to Tarantella.
By default, Tarantella Setup creates a person object for a Tarantella Administrator with username "Administrator", authenticating using root's password on the host on which Tarantella is installed.
Once users are authenticated, the web browser or Native Client shows their webtop.
Along one side of their webtop, users see a column of icons with labels. We call these links, as they're just like links on the web: you click them to display something. In Tarantella, webtop links give access to applications and documents. A user can only access the applications and documents that are on their webtop.
When Tarantella is first installed, all users have links on their webtop for a few simple applications and documents, such as xterm, the Tarantella web site, and the Using Your Webtop online documentation. Tarantella Administrators have extra links, including the Tarantella Administration Guide and the Tarantella administration tools Object Manager and Array Manager.
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To display an application, just click the link. Tarantella Administrators can configure applications to appear in many different ways, for example within the web browser window or in separate free-floating windows to resemble an application running on the client device. After clicking the link, users might be prompted for another username and password. This is authentication information for the application server: the host on which the application is installed. These details can be cached securely so users don't need to enter them more than once for each application server. |
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When the application appears, users can interact with it just as if it were running locally. To show that the application's running, its webtop icon includes a small cog overlay. |
Applications have three resumability settings:
| Setting | Description |
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| Never resumable | Each time a user clicks the webtop link, a new instance of the application starts. When a user logs out, applications configured to be "never" resumable all exit. |
| Tarantella Webtop Session resumable | Once the application starts, it's resumable until the user logs out of Tarantella (ending their webtop session). Users can return to the application at any time by clicking the link again (the cog overlay shows that the application's currently running). Logging out of Tarantella exits the application. |
| Always resumable | Once the application starts, it's resumable until the user exits the application. The user can log out of Tarantella and log back in (from anywhere), and can resume the application by clicking the webtop link. |
Just like logging out of a computer system, logging out of Tarantella is important. It lets Tarantella shut down any applications that needn't run any more, and makes sure nobody can use a user's applications in their name without permission.
 | To log out of Tarantella, web browser users click the "X" icon
in the lower-left corner of their webtop and then click OK when prompted for confirmation.
Native Client users choose Log Out from the Webtop menu and then click OK when prompted for confirmation. |
If someone closes their web browser or Native Client without explicity logging out, or (for example) if their web browser or client device crashes, they aren't logged out of Tarantella. The user can log in to Tarantella again and can resume applications configured to be Tarantella Webtop Session resumable or Always resumable.
Graham Green starts his web browser and goes to the URL
http://seattle.indigo-insurance.com/tarantella. He's already
logged in to this version of Tarantella before, so he
quickly sees the login page and isn't asked to install a Java
archive (it's already installed).
Graham has a person object in the organizational hierarchy, which is configured to use his UNIX password on seattle.indigo-insurance.com. He types the username "Graham Green" and the password, then clicks Log In. A few moments later Graham's webtop appears.
Graham wants to get back to the document he was working on earlier, so he clicks the "Write-o-Win" link (which shows a cog wheel overlay) to resume the application. A window appears almost immediately, showing the word processor exactly as he left it with the cursor positioned at the end of the document.
Graham wants to check some figures in a spreadsheet, so he clicks "Cash-o-Win". This doesn't have a cog, so a new instance of the application starts. Tarantella prompts Graham for his username and password on the host berlin.indigo-insurance.com, which he hasn't logged in to before (Tarantella chose that application server as it was the least loaded of the set of six application servers configured to run this application). He checks the box to save the password so he doesn't have to type it again.
After a few seconds a new window appears showing the application, and a cog appears over the webtop icon. After performing the calculation Graham exits the application and the cog disappears.
Graham writes some more of his document, and then has to leave for a meeting on another site. He logs out of Tarantella -- without exiting any applications -- and heads for the meeting. He'll find a spare client device there to log in later and pick up where he left off.
