Network Services

1
Network Services

2
Distributed Application Paradigms
3
Network Services

• Services can be located through a directory
  service.
• Services can be discovered using a lookup service
  and a discovery protocol (e.g., JRMP).
• Services can join the community and register
  their availability with one or more lookup
  services.

4
Network Services

• The network is seen as federations of services
  and clients.
• Services include applications, databases,
  servers, devices, information systems, mobile
  appliances, storage, printers.
• Clients are requesters (and consumers) of
  services

5
Network Services

• Each federation of client and service(s)
• is independent of other federations and may
  co-exist with other federations.
• is transient the union lasts only for as long as
  the service(s) is/are needed.
• There is no centralized control system
• There is no centralized administration of
  available services
• There are no policies that restrict federation
  between a client and services.

6
Jini Network Technology

• Jini provides an infrastructure and a programming
  model based on federation of network services.
• It uses RMI to transport objects
• It allows a client program to make use of
  services without being aware of the wire
  protocol used by the service.
• It provides the concept of leasing a service a
  client requests the lease of a service, which
  expires after a time period.

7
Jini Network Technology

• A service is an object that implements a service
  API.
• A client looks up a service that supports an API.
• A discovered service object is sent to the
  client.
• The client and the service only have to agree on
  the API, and not how requests and responses are
  transmitted (e.g., protocol)

8
Jini Network Technology

• Jini is to network services what universal
  plug-and-play is to system devices it allows
  interoperability of clients and services
  regardless of transport and wire protocols.

9
Figure from Jini By Example
10
Jini Network Technology
(I)
(II)
From http//java.sun.com/developer/products/jini/
arch2_0.html
11
Jini Network Technology
(III)
(IV)
12
Jini code samples

• HelloWorld
• nugget JiniExample1 illustrates network service
  lookup
• nugget JiniExample3 illustrates network service
  discovery
• (Noel Enetes Nuggets for Jini (code samples),
  http//www.enete.com/download/index.html_nuggets_
  )
• Calculator
• See jini by Example paper from California
  Software Lab.
• California Software Lab Jini by Example
  Whitepaper, http//www.cswl.com/whiteppr/tutorials
  /jini.html

13
Applications

• Shared network devices such as printers.
• Service (software, video, music, etc.) on demand
• Shareware

14
Sources of Information

• Jini(tm) Network Technology, http//www.sun.com/ji
  ni/
• Core Jini, a book by Keith Edwards
• Jan Newmarch's Guide to JINI Technologies,
  http//jan.netcomp.monash.edu.au/java/jini/tutoria
  l/Jini.xml
• Jini Planet, http//www.kedwards.com/jini/
• Directory of Jini Resources on the net
  Tutorials_and_Examples, http//litefaden.com/sv/jd
  /Tutorials_and_Examples/

15
Sources of Information

• Jini whitepaper, http//wwwwswest.sun.com/jini/whi
  tepapers/jini-execoverview.pdf
• California Software Lab Jini by Example
  Whitepaper, http//www.cswl.com/whiteppr/tutorials
  /jini.html
• Noel Enetes Nuggets for Jini (code samples),
  http//www.enete.com/download/index.html_nuggets_
  
• Jini.org -- The Community Resource for Jini(tm)
  Technology, http//www.jini.org/