RMIIIOP and JNDI

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RMI-IIOPandJNDI
Celsina Bignoli bignolic_at_smccd.net
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Java RMI-IIOP

• Java Remote Method Invocation over Internet
  Inter-ORB Protocol
• Mechanism that allows objects to communicate
  across a network
• Special version of RMI, compliant with CORBA
• Uses java.rmi and javax.rmi packages

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Remote Interface

• separation between
• Interface exposes to the client what methods can
  be invoked on an object and what are their
  parameters
• Implementation the programming logic provided by
  the object
• in RMI-IIOP, need to define a Remote Interface
  which extends java.rmi.Remote

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Remote Object Implementation

• Implements the remote interface
• To allow remote clients to invoke its methods,
  must either
• Extend javax.rmi.PortableRemoteObject
• Be manually exported using javax.rmi.PortableRemot
  eObject.
• exportObject()

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Location transparency

• RMI-IIOP masks weather the object you are
  invoking is local or remote
• Uses a stub to accept method calls locally and
  delegate those calls to the actual object
  implementation which might reside across the
  network
• Uses a skeleton on the remote host to receive
  calls over the network and delegate the calls to
  the object implementation.
• Stubs and skeletons are automatically generated
  by a tool, called rmic, provided as part of the
  Java RMI-IIOP implementation

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Stubs and Skeletons
Client
Implementation Object
Remote Interface
Remote Interface
Stub
Skeleton
Network
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Object Serialization

• Conversion of a Java object into a bit-blob
  representation
• Must implement the java.lang.Serializable
  interface (marker interface, no methods)
• Rules for member variables
• All primitive types are serializable and will be
  serialized unless marked as transient
• Objects marked as transient will not be
  serialized
• Objects not marked as transient must be
  Serializable

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RMI-IIOP and Object Serialization

• Java RMI-IIOP uses serialization for passing
  parameters via remote method invocation.
• A parameter is serialized and passed by-value
• Java RMI-IIOP can also simulate
  pass-by-reference.
• The parameter must be declared as a remote object
• The stub for the remote object is serialized and
  passed by-value.