4/3/10 1 Network Services


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4/3/10 1 Network Services

  1. 1. Network Services
  2. 2. Distributed Application Paradigms
  3. 3. Network Services <ul><li>Services can be located through a directory service . </li></ul><ul><li>Services can be discovered using a lookup service and a discovery protocol (e.g., JRMP) . </li></ul><ul><li>Services can join the community and re g ister their availability with one or more lookup services. </li></ul>
  4. 4. Network Services <ul><li>The network is seen as federations of services and clients . </li></ul><ul><li>Services include applications , databases , servers , devices , information systems , mobile appliances, storage, printers . </li></ul><ul><li>Clients are requesters (and consumers ) of services </li></ul>
  5. 5. Network Services <ul><li>Each federation of client and service(s ): </li></ul><ul><ul><li>is independent of other federations and may co-exist with other federations. </li></ul></ul><ul><ul><li>is transient : the union lasts only for as long as the service(s) is/are needed . </li></ul></ul><ul><li>There is no centralized control system : </li></ul><ul><ul><li>There is no centralized administration of available services </li></ul></ul><ul><ul><li>There are no policies that restrict federation between a client and services . </li></ul></ul>
  6. 6. Jini Network Technology <ul><li>Jini provides an infrastructure and a programming model based on federation of network services . </li></ul><ul><li>It uses RMI to transport objects </li></ul><ul><li>It allows a client program to make use of services without being aware of the “wire protocol” used by the service. </li></ul><ul><li>It provides the concept of leasing a service : a client requests the lease of a service , which expires after a time period . </li></ul>
  7. 7. Jini Network Technology <ul><li>A service is an object that implements a service API. </li></ul><ul><li>A client looks up a service that supports an API. </li></ul><ul><li>A discovered service object is sent to the client . </li></ul><ul><li>The client and the service only have to agree on the API , and not how requests and responses are transmitted (e.g., protocol ) </li></ul>
  8. 8. Jini Network Technology <ul><li>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 . </li></ul>
  9. 9. Figure from “Jini By Example”
  10. 10. Jini Network Technology From http://java.sun.com/developer/products/jini/arch2_0.html (I) (II)
  11. 11. Jini Network Technology (III) (IV)
  12. 12. Jini code samples: <ul><li>HelloWorld – </li></ul><ul><ul><li>“ nugget” JiniExample1 illustrates network service lookup </li></ul></ul><ul><ul><li>“ nugget” JiniExample3 illustrates network service discovery </li></ul></ul><ul><li>( Noel Enete’s Nuggets for Jini (code samples), http://www.enete.com/download/index.html#_nuggets_) </li></ul><ul><li>Calculator </li></ul><ul><ul><li>See “jini by Example” paper from California Software Lab. </li></ul></ul><ul><li>California Software Lab | Jini by Example – Whitepaper , http:// www.cswl.com/whiteppr/tutorials/jini.html </li></ul>
  13. 13. Applications <ul><li>Shared network devices such as printers . </li></ul><ul><li>Service (software, video, music, etc.) on demand </li></ul><ul><li>Shareware </li></ul>
  14. 14. Sources of Information <ul><li>Jini(tm ) Network Technology , http://www.sun.com/jini/ </li></ul><ul><li>Core Jini, a book by Keith Edwards </li></ul><ul><li>Jan Newmarch's Guide to JINI Technologies , http://jan.netcomp.monash.edu.au/java/jini/tutorial/Jini.xml </li></ul><ul><li>Jini Planet , http://www.kedwards.com/jini/ </li></ul><ul><li>Directory of Jini™ Resources on the net: Tutorials_and_Examples , http://litefaden.com/sv/jd/Tutorials_and_Examples / </li></ul>
  15. 15. Sources of Information <ul><li>Jini whitepaper , http://wwwwswest.sun.com/jini/whitepapers/jini-execoverview.pdf </li></ul><ul><li>California Software Lab | Jini by Example – Whitepaper , http://www.cswl.com/whiteppr/tutorials/jini.html </li></ul><ul><li>Noel Enete’s Nuggets for Jini (code samples), http://www.enete.com/download/index.html#_nuggets_ </li></ul><ul><li>Jini.org -- The Community Resource for Jini(tm ) Technology , http://www.jini.org/ </li></ul>