Location Based Information Service using CORBA

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Location Based Information Service using CORBA

• CS597 Direct Reading
• Madhu Narayanan
• Rahul Vaghela
• Advisor Dr. Yugi Lee

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Architecture of mobile network and LBIS

• Every geographical area is headed by a
  base-station
• The base station is responsible to keep all the
  clients, within its area within the network
• Ideally each base-station is accompanied by a
  computing resource which consists of components
  used for LBIS
• If the cost of maintaining all the components at
  every base station is high, they can be placed
  remotely and used by the client. This may cause
  latency in transition of information.

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Architecture of our LBIS

• The architecture we are following is based on the
  middleware to support QoS (Quality of Services)
  such as scalability, reliability, security,
  client preferences.
• The system consists of client, server, two
  middle-layer components and databases.
• The Server instantiates the components, client
  asks the services from these components by method
  of invocation.
• Components interact with the database and provide
  the output at the client.

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Why N Tier?

• A middle tier was added between the user system
  interface client environment and the database
  management server environment.
• The middle tier can perform queuing, application
  execution, and database staging.
• The three tier client/server architecture has
  been shown to improve performance for groups with
  a large number of users (in the thousands)
• Improves flexibility when compared to the two
  tier approach

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Middleware

• Middleware is a layer of software between the
  network and the applications that provides
  services such as identification, authentication,
  authorization, directories, and security
• In today's Internet, applications usually have to
  provide these services themselves, which leads to
  competing and incompatible standards

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CORBA Architecture in nutshell
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Flow of Operations
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Architecture
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UML Sequence Diagram
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Logical Flow of Execution (Cont)

• The input parameters are appended as one string
  and passed to the scheduler module as one string
  object.
• The scheduler de-fragments the string takes the
  cell number of the customer alone and sends a
  query to the customer database asking for the
  corresponding priority lever for that number and
  the cell id (which is randomly assigned).
• The priority level is returned to the scheduler
  which queues requests based on the priority
  levels.

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Logical Flow of Execution (Cont)

• The request string query with the highest
  priority is sent to the position locator database
  which has entry for the zip code based on the
  location ID.
• The zip codes passed to the CPU is appended to
  the string and sent along with the information
  type as query to the information database, which
  returns the corresponding information.
• The information retrieved from the information
  database is sent to the client applet for
  display.

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Our Implementation

• Technology
• Programming Language Java
• Middleware CORBA (VisiBroker)
• Database Access
• JDBC-OBDC for connectivity
• Tools JDK 1.3, and Visibroker

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IDL File

• module Infoprovider
• interface CPU
• string infoop()
• interface Scheduler
• queue(in string name)

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Implementation Files

• CPUImpl Performs the function of locating
  the client and getting the information he has
  requested for
• SchedulerImpl Schedules the incoming
  requests and creates an instance of CPUImpl and
  calls it with parameters passed

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Server file

• //Initialize the ORB.org.omg.CORBA.ORB orb
  org.omg.CORBA.ORB.init(args,null)
• //Get a reference to the root POAPOA rootPOA
  POAHelper.narrowa(orb.resolve_initial_references(
  "RootPOA"))

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Server Cont

• //Create policies for our persistent POA
  org.omg.CORBA.Policy policies
  rootPOA.create_lifespan_policy(LifespanPolicyValue
  .PERSISTENT)
• //Create the servant Create Instance of
  SchedulerImpl and Wait for incoming
  requests orb.run()

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Client file

• //Initialize the ORB. org.omg.CORBA.ORB orb
  org.omg.CORBA.ORB.init(args,null)
• //Basic bind function for ORB Infoprovider.Sched
  uler manager Infoprovider.SchedulerHelper.bind(
  orb, "/infoprovider_poa", userId)

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Benefits of using CORBA (1)

• CORBA implements the specifications of OMG. They
  are written and adopted by nearly 800 member
  companies of OMG. Any company, institution or
  government agency can join OMG, and influence the
  specifications
• CORBA Orbs are available on every major operating
  system in use today
• CORBA Orbs also exist to bind to a wide variety
  of languages including C, Ada, COBOL,
  Smalltalk, and Java.
• Using IIOP, a CORBA ORB developed by one vendor
  (Visigenic, for instance) can retrieve and
  manipulate objects obtained from a remote ORB
  developed by another vendor (IONA, for instance)

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Benefits of using CORBA (2)

• Object Based
• Supports transaction processing between two
  systems
• Easy integration with existing computer systems
  guarantees that the investment is risk free
• New components can be easily added to the
  existing ones
• Proven Interoperability

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Conclusion

• CORBA being open source, is being widely used in
  the industry
• LBIS system requires a middleware architecture
  which needs to be scalable and reliable due to
  frequent hand-offs, resource fluctuations, and
  the complexity involved due to large amount of
  data processing. CORBA with its inherent features
  perfectly fits the picture
• CORBA has proven interoperability and is a must
  feature for LBIS due the variety of clients using
  different platforms.