The server-side mapping for interfaces provides an up-call API for the Ice run time: by implementing methods in a servant class, you provide the hook that gets the thread of control from the Ice server-side run time into your application code.
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Skeleton Classes in Python
On the client side, interfaces map to proxy classes. On the server side, interfaces map to skeleton classes. A skeleton is an abstract base class from which you derive your servant class and define a method for each operation on the corresponding interface. For example, consider our Slice definition for the
The Python mapping generates the following definition for this interface:
The important points to note here are:
- As for the client side, Slice modules are mapped to Python modules with the same name, so the skeleton class definitions are part of the
- The name of the skeleton class is the same as the Slice interface (
- The skeleton class contains a comment summarizing the method signature of each operation in the Slice interface.
- The skeleton class is an abstract base class because its constructor prevents direct instantiation of the class.
- The skeleton class inherits from
Ice.Object(which forms the root of the Ice object hierarchy).
Ice.Object Base Class for Python Servants
Object is mapped to the
Ice.Object class in Python:
The methods of
Ice.Object behave as follows:
This method returns
trueif target object implements the given type ID, and
ice_pingprovides a basic reachability test for the servant.
This method returns a string array representing all of the type IDs implemented by this servant, including
This method returns the type ID of the most-derived interface implemented by this servant.
This static method returns the type ID of the target class:
::Ice::Objectwhen called on
Servant Classes in Python
In order to provide an implementation for an Ice object, you must create a servant class that inherits from the corresponding skeleton class. For example, to create a servant for the
Node interface, you could write:
By convention, servant classes have the name of their interface with an
I-suffix, so the servant class for the
Node interface is called
NodeI. (This is a convention only: as far as the Ice run time is concerned, you can choose any name you prefer for your servant classes.) Note that
Filesystem._NodeDisp, that is, it derives from its skeleton class.
As far as Ice is concerned, the
NodeI class must implement only a single method: the
name method that is defined in the
Node interface. This makes the servant class a concrete class that can be instantiated. You can add other member functions and data members as you see fit to support your implementation. For example, in the preceding definition, we added a
_name member and a constructor. (Obviously, the constructor initializes the
_name member and the
name function returns its value.)
Server-Side Normal and
idempotent Operations in Python
Whether an operation is an ordinary operation or an
idempotent operation has no influence on the way the operation is mapped. To illustrate this, consider the following interface:
The mapping for this interface is shown below:
Note that the signatures of the methods are unaffected by the