Jini Technology: Distributed Network Computing Explained
This paper provides an overview of Jini, a software architecture developed by Sun Microsystems designed to simplify the connection and sharing of networked devices. It examines Jini's four core program layers — the Look-up Service, JavaSpaces, Remote Method Invocation (RMI), and Discovery Protocol — explaining how each layer enables devices to dynamically register, discover, and communicate with one another. The paper also compares Jini and RMI to CORBA, discusses the long-term federated network vision articulated by Jini architect Jim Waldo, and addresses the technology's limitations and market uncertainties, including security concerns, scalability issues, and Sun Microsystems' financial challenges.
- Introduction to Jini: Overview of Jini's purpose and distributed computing potential
- The Four Program Layers of Jini: Enumeration and brief description of Jini's four layers
- Look-up Service and JavaSpaces: How devices register, discover, and share objects
- Remote Method Invocation and Discovery Protocol: RMI, CORBA comparison, and plug-and-execute capabilities
- The Long-Term Vision for Jini: Federated network-centric architecture and Jim Waldo's vision
- Market Challenges and Limitations: Security, scalability, and commercial uncertainties for Jini
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What makes this paper effective
- The paper organizes a technically complex subject into a clear, layered explanation, moving from high-level concept to specific architectural components before broadening back to strategic implications.
- Each of Jini's four layers is explained with a concrete functional example, making abstract distributed computing concepts accessible to a general technical audience.
- The paper balances promotional framing with critical analysis, acknowledging real market and technical limitations rather than presenting Jini uncritically.
Key academic technique demonstrated
The paper effectively synthesizes multiple primary and secondary sources — trade publications, developer journals, and technical encyclopedias — to construct a coherent technical overview. Each claim about Jini's architecture or market position is attributed to a specific source, demonstrating disciplined use of evidence in an expository technology paper.
Structure breakdown
The paper opens with a definition and competitive context, then enumerates Jini's four architectural layers. It drills into each layer in dedicated sections, compares Jini/RMI to CORBA, presents the long-term federated vision from the lead architect, and closes with an honest assessment of the technology's commercial uncertainties. This funnel-and-broaden structure — concept → components → vision → critique — is well suited to expository technical writing.
Introduction to Jini
Jini is software from Sun Microsystems that seeks to simplify the connection and sharing of devices — such as printers and disk drives — on a network. Unlike devices that require installation and boot-up processes to be added to a computer or a network, a device that uses Jini will announce itself to the network, provide details about its capabilities, and immediately become accessible to other devices. It is therefore possible to leverage Jini to create distributed computing, whereby capabilities are shared among machines on a common network. Users can access the features of any device on the network, and the desktop computer does not need to hold all the memory, storage, and processing power required to use a given device. Because Jini has the potential to make operating systems incidental to the power of networks, some view it as capable of reducing the influence of the Microsoft Windows operating system.
The Four Program Layers of Jini
Jini is comprised of four major program layers:
- Look-up Service
- JavaSpace
- Remote Method Invocation (RMI)
- Discovery Protocol
When a device is plugged into the Jini network, it is immediately registered by the Directory Service layer as a member of the network. Its required program objects are placed in a JavaSpace layer so that other network members can discover and download them when needed. Communication with objects in JavaSpace is carried out using the Remote Method Invocation interface and layer. Finally, the layer supporting the Discovery Protocol enables devices, users, and applications to announce and register themselves and to discover others on the network.
Look-up Service and JavaSpaces
Jini's Look-up Service is different from most directory services because it is a dynamically built directory (Schwartz, 1999). Once a device registers itself with the Look-up Service, it becomes an object that can be accessed by other devices, which may or may not be registered depending on user preference. For example, a user can register a color printer and place it inside the Look-up Service, which records the necessary printer code and driver information. Another user can plug a digital camera into the network and choose not to register the device. The camera user looking for a color printer will find it in the Look-up Service, and the necessary code or driver information from the printer is sent to the camera, allowing the printer and camera to communicate directly with one another without returning to the Look-up Service. If a device becomes unavailable, it is automatically removed from the Look-up Service — a contrast with standard directory services, where the unavailable device would remain listed despite being inaccessible.
JavaSpaces use a simple mechanism for accessing and processing distributed objects (Shah, 1998). A client application makes contact with a JavaSpaces server and requests a certain type of object by sending a template describing what the object looks like. The space then responds with the entry that best fits the template description. The client sends a read operation to make a copy of the entry within that space and work with it. The client can also perform a take operation to remove an existing entry from that space, deleting it from the list of entries. The client then processes the entry object as needed. Once completed, it can perform a write operation to put that entry object back into the space so that others can access it.
Bibliography
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Jini. Retrieved April 28, 2004 from Webopedia: http://www.webopedia.com/TERM/J/Jini.html
Jini. Retrieved April 28, 2004 from TechTarget:
Perrone, P. and Chaganti, V. (1999, November). Jini in the box. Embedded Systems Programming. Retrieved April 29, 2004.
Schwartz, E. (1999, January 25). Sun lets Jini out of the bottle. InfoWorld. Retrieved April 29, 2004 from
Shah, R. (1998). The skinny on Jini. Retrieved April 29, 2004 from JavaWorld: http://www.javaworld.com/javaworld/jw-08-1998/jw-08-jini.html
Venners, B. (1999, August). The Jini vision. Retrieved April 29, 2004 from JavaWorld: http://www.javaworld.com/javaworld/jw-08-1999/jw-08-jiniology.html
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