Objektově orientované systémy

Objektově orientované systémy

Kód předmětu: NSWI068 Přednáší: František Plášil

Otázky

• Explain why is the classical client-server contract considered "asymmetric". Is there any remedy to this problem?
  • possible explanation
• Explain the difference between inheritance and subtyping. [1]
  • Subtyping is relation between interfaces, inheritance is relation between implementations.
• What kind of covariant and contravariant type changes would you recommend in method inheritance?
  • takové to A<:A' vs. A:>A' a B<:B' vs. B:>B'
• What is an implicit specialization of self? Write an example.
• In CORBA, can a servant incarnate multiple object references at the same time? If yes, write a code fragment illustrating the basic idea of constructing such references on the server side.
  • yes, rootPOA.create_id_uniqueness_policy(IdUniquenessPolicyValue.MULTIPLE_ID); ... _RepId = _defaultServant._all_interfaces(); ... create_reference_with_id(objectId, _RepId);
  • example
• Explain the Tie technique, and provide an example of its use in an implementation class supporting two IDL interfaces (not in inheritance relation); give at least two reasons of importance.
  • Delegate implementation to user-supplied servant [2], example.
• Draw the sequence diagram of unsuccessfully commited transaction (commit resulted into rollback) involving at least 2 resources.
  • page 29 at [3]
• Explain the basic idea of the MDA and MOF technologies.
• Does CORBA Event Service inherently involve buffering? If yes, explain why and how it is typically implemented. Can Event Channels be directly connected (one being a supplier and another being its consumer); if yes provide a program fragment illustrating their connection?
  • buffer, event service examples, chained event channels
• Component-based programming. Explain what ADL is and what makes the basic abstractions which can be specified in ADL.
  • ADL is modeling notation to support architecture-based development.
  • Essential architecture modeling featuers are components, connectors and architectural configurations. [4]
• Explain the fragile base class problem and inheritance anomaly.