Java Card中小程序的坚固性

Question

I developed an applet in Java Card and it works fine. Now I am working on the sturdiness of this applet and more precisely, what happens if the card is deplugged during the applet execution for example.

I am wondering if there is an Exception which handle this kind of things ?

I am searching for something like :

try {
...
}
// If the card is disconnected while the applet execution
catch (Exception e) {
...
}

Thank you in advance.

Answer 1

As the smart cards haven't any battery inside, you can't have any try ... catch ... like this. Alternatively you can take advantages of Transactions . The Transaction APIs are provided just for your goal. The operations that are between beginTransation() and commitTransation() methods, apply only if the commitTransation() complete successfully. And if any exeption/card tear or card reset happens before commitTransation() , everything returns to its original state (ie to the state that it has before beginTransaction() )

It is like this :

    .
    .
    JCSystem.beginTransaction();
    //put your critical code here.
    JCSystem.commitTransaction();
    .
    .

You can also use JCSystem.commitTransaction(); to terminate a transaction in a specific situation as follow :

    .
    .
    JCSystem.beginTransaction();

    //put your critical code here.
    if (condition) {
    JCSystem.commitTransaction();
    }

    JCSystem.commitTransaction();
    .
    .

Note that:

1. Transactions have a limited buffer in cards. So you can't put whole the program inside a transaction. But for typical critical methods, it has enough buffer size.
2. You can't use nested Transactions.