Chapter 20 corba fm
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Soft computing Lab Mannual, Distributed systems
| Figure 20.1 IDL interfaces Shape and ShapeList struct Rectangle{ 1 long width long height; long x; long y; } ; struct GraphicalObject { 2 string type Rectangle enclosing boolean isFilled; }; interface Shape { 3 long getVersion() ; GraphicalObject getAllState() ; // returns state of the GraphicalObject }; typedef sequence 4 interface ShapeList { 5 exception FullException{ }; 6 Shape newShape(in GraphicalObject g) raises (FullException); 7 All allShapes(); // returns sequence of remote object references 8 long getVersion() ; }; SECTION 20.2 CORBA RMI 831 Type Object : Object is the name of a type whose values are remote object references. It is effectively a common supertype of all of IDL interface types such as Shape and ShapeList Exceptions in CORBA IDL: CORBA IDL allows exceptions to be defined in interfaces and thrown by their methods. To illustrate this point, we have defined our list of shapes in the server as a sequence of a fixed length (line 4) and have defined FullException (line 6), which is thrown by the method newShape (line 7) if the client attempts to add a shape when the sequence is full. Invocation semantics Remote invocation in CORBA has at-most-once call semantics as the default. However, IDL may specify that the invocation of a particular method has maybe semantics by using the oneway keyword. The client does not block on oneway requests, which can be used only for methods without results. For an example of a oneway request, seethe example on callbacks at the end of Section 20.2.1. Download 234.39 Kb. Share with your friends:
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