The JCSystem class contains the method getAppletShareableInterfaceObject, which is invoked by a client applet to communicate with a server applet.

The Java Card RE shall implement this method to behave as follows:

1. The Java Card RE searches its internal applet table which lists all successfully installed applets on the card for one with serverAID. If not found, null is returned.

2. If the server applet instance is not a multiselectable applet instance and is currently active on another logical channel, a SecurityException is thrown. See Section 4.2, Multiselectable Applets.

3. The Java Card RE invokes this applet's getShareableInterfaceObject method, passing the clientAID of the caller and the parameter.

4. A context switch occurs to the server applet, and its implementation of getShareableInterfaceObject proceeds as described in the previous section. The server applet returns a SIO (or null).

5. getAppletShareableInterfaceObject returns the same SIO (or null) to its caller.

For enhanced security, the implementation shall make it impossible for the client to tell which of the following conditions caused a null value to be returned:

• The serverAID was not found.

• The server applet does not participate in inter-applet communication.

• The server applet does not recognize the clientAID or the parameter.

• The server applet does not communicate with this client.

• The server applet does not communicate with this client as specified by the parameter.

• The applet's getShareableInterfaceObject method throws an uncaught exception.