=== 6.2.7.2 JCSystem.getAppletShareableInterfaceObject Method ===

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 [[4.2_Multiselectable Applets| 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.