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THE JINI TECHNOLOGY

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Title: THE JINI TECHNOLOGY


1
THE JINI TECHNOLOGY
  • Alessio Zumbo

1997s023_at_educ.disi.unge.it
2
Index
  • Middleware
  • Jini intro
  • Service
  • Lookup Service
  • RMI
  • Leasing
  • Transactions
  • Events
  • Components


3
Index
  • The infrastructure
  • The programming model
  • Discovery Join Lookup


4
Middleware
  • Is a layer between network operating systems and
    application components.

Application component
Middleware
Network operating system
5
Middleware requirements
  • Scalability
  • Openness
  • Heterogeneity
  • Fault-tollerance
  • Resource sharing

6
Jini intro (1/3)
  • Jini is a technology that is based on Java and
    Tcp-IP and that, using net protocols, allows to
    put in communication different objects between
    they in an only one network.

7
Jini intro (2/3)
  • In practical, every time that a new device comes
    connected to the circuit, before announces who is
    and what is in a position to making and then it
    explains as it must be used, through its
    interface.

8
Jini intro (3/3)
  • As an example a printer, in the moment in which
    it is connected to a Jini community, before will
    be introduced and then it will as an example
    expose to its interface, containing the service
    print.
  • If subsequently a Jini refrigerator must have
    need to print a page, it will be sufficient that
    it goes to search who, in the community, puts to
    disposition the service print and then to demand
    the execution.

9
Service (1/3)
  • A service can be computation, memory, a
    communication channel, a dispositive hardware, or
    an other customer.
  • Two examples of services are to print a
    document and translate a document from a format
    to an other.
  • A system of Jini would not have to be believed
    like with about clients and server, or customers
    and programs, or programs and databases, rather,
    a Jini system consists to accomplish one
    particular operation.

10
Service (2/3)
  • The dynamics nature of a Jini system allows to
    the services of being added or withdraws to you
    anytime.
  • Jini supplies the mechanisms for the
    construction, the search, the communication and
    the use of the services of the distributed system.

11
Service (3/3)
  • The services in a Jini system communicate between
    they using a protocol, that it is with of
    interfaces written in the language of Java
    programming.

12
Lookup Service (1)
  • The services are find from the Lookup Service,
    which it is not other that a table containing the
    interfaces that describe the functionalities of
    the present services in the Jini community.

13
Lookup Service (2)
  • In adding are stored attributes, that they serve
    in order to specify in more complete way the
    service. Typical attributes are the name, the
    description and the location.

14
Lookup Service (3)
  • A service is added to the Lookup Service using
    two protocols calls to you discovery and join
    in the first place the service characterizes the
    Lookup Service (using the protocol discovery) and
    then it joins to it (using the protocol join).

15
Java Remote Method Invocation (RMI) (1/2)
  • The communication between the services happens
    using Remote Method Invocation (RMI) supplied
    from Java. RMI not only allows to transfer gives
    to you from an object to other through the net,
    but also complete objects, comprised the code.

16
Java Remote Method Invocation (RMI) (2/2)
  • Great part of the semplicity of the Jini system
    is concurred from this ability to move the code,
    encapsulated in to the object , through the net.

17
Leasing (1/4)
  • The access to many of the services in to the
    environment Jini is based on the leasing. A
    leasing is one concession of access guaranteed
    for a sure period of time.

18
Leasing (2/4)
  • Every leasing is negotiates between the
    petitioner and the supplier of the service
  • a service is asked for a sure period
  • the access it is assigned for a sure time,
    possibly holding in consideration the demanded
    period.

19
Leasing (3/4)
  • If a leasing is not renewed before that it is
    exausted, or because the resource is not more
    necessary, or client or the net comes to lack, or
    it is not allowed with the leasing of being
    renewed, then the resource can be freed.

20
Leasing (4/4)
  • The leasing can be of two types exclusive or
    not exclusive
  • exclusive assure that no other can use the
    resource (to obtain an other leasing) during the
    period of the leasing, those, instead,
  • not exclude, allows a shared use to you of the
    resource (is granted more leasing on the same
    resource).

21
Transactions (1/3)
  • A series of operations, to the inside of single
    service or reported more services, can be
    inglobate in one transaction. A transaction is
    indivisible in unity of execution therefore or
    the operations of a transaction come executed
    all, or the transaction must not have some effect
    on the system.

22
Transactions (2/3)
  • In particular Jini in order to guarantee a
    transaction uses the protocol of commit to two is
    made (two-phase commit). Such protocol
    remembers, in its essential lines, a wedding, the
    decision of two persons comes ratified collection
    and from a third person, that it celebrates the
    wedding.

23
Transactions (3/3)
  • So that the wedding has place, is necessary that
    both the participants express their will to marry
    themselves celebrating, during the first phase,
    collects desire to marry itself separately,
    express from the two participants, in order then,
    in a second phase, to give they news that the
    wedding has happened.

24
Events
  • The Jini architecture supports the distributed
    events.
  • An object can allow that other objects are
    recorded to particular events of the object and
    receive a notification in the case happen such
    event.

25
Components (1/3)
  • The members of a Jini system can be segmetated in
    three categories the infrastructure, the model of
    programming and the services. The infrastructure
    is with of the members whom the development of
    the federation system Jini allows, while the
    services are the entities to the inside of the
    federation.

26
Components (2/3)
  • The programming model the set of the interfaces
    that the construction of reliable services
    allows, comprised those that make part of the
    infrastructure and those that join the
    federation.
  • These three categories, although distinguished
    and separable, are interlaced to such point that
    their distinction can seem little clear.

27
Components (3/3)
  • Is possible to develop systems that they have
    some of the functionalities of the Jini system
    with of varying in all and the three categories.

28
The infrastructure
  • The technological infrastructure of Jini includes
    the following a distributed security system,
    integrated with RMI, that extends the model of
    emergency of the Java platform to the world of
    the distributed systems discovery and join
    protocols, service protocols that concur with the
    service to discover, become part, and inform the
    other members of the federation lookup service,
    that serve like a warehouse of services, it's a
    table where the lines are objects written in Java.

29
The infrastructure (1/2)
  • The technological infrastructure of Jini includes
    the following a distributed security system,
    integrated with RMI, that extends the model of
    emergency of the Java platform to the world of
    the distributed systems discovery and join
    protocols, service protocols that concur with the
    service to discover, become part, and inform the
    other members of the federation lookup service,
    that serve like a warehouse of services, it's a
    table where the lines are objects written in Java.

30
The infrastructure (2/2)
31
The programming model
  • The interfaces that compose the model of
    programming of Jini are the following
  • leasing interface it defines a way in order to
    allot and free the resources using a rinnovabile
    model and based on the duration
  • event and notification interface they are an
    extension of the model of event used in the
    JavaBeans members for distributed systems, they
    allow the communication based on the events
    between Jini services
  • transaction interface allows a group of
    services to cooperate second the approach of the
    transactions in such way that the change made
    from the group happens in atomic way.

32
Discovery Join Lookup (1/5)
  • The heart of the Jini system is a trio of
    protocols called discovery, join, and lookup. A
    pair of these protocolsdiscovery and joinoccur
    when a device is plugged in.

33
Discovery Join Lookup (2/5)
  • Discovery occurs when a service is looking for a
    lookup service with which to register.
  • Join occurs when a service has located a lookup
    service and wishes to join it.
  • Lookup occurs when a client or user needs to
    locate and invoke aservice described by its
    interface type (written in the Java programming
    language) and possibly other attributes.

34
Discovery Join Lookup (3/5)
35
Discovery Join Lookup (4/5)
36
Discovery Join Lookup (5/5)
37
The end
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