A Bank Server

Example 21-1 defined a RemoteBank interface and a bank client program. Example 21-2 is a RemoteBankServer class that implements the RemoteBank interface and acts as a server for the Bank.Client program. This class includes a main( ) method so it can be run as a standalone program. This method creates a RemoteBankServer object and registers it with Naming.rebind( ), so that clients can look it up. It reads the system property bankname to determine what name to use to register the bank, but uses the name FirstRemote by default. (This is the same name that the Bank.Client uses by default as well.)

RemoteBankServer implements the RemoteBank interface, so it provides implementations for all remote methods defined by that interface. It also defines some utility methods that are not remote methods, but that are used by the remote methods. Note that RemoteBankServer includes an inner Account class that stores all the information about a single bank account. It maintains a hashtable that maps from account names to Account objects. The various remote methods look up the named account, verify the password, and operate on the account in some way. Any RMI remote object must be able to handle multiple, concurrent method invocations because multiple clients can be using the object at the same time. RemoteBankServer uses synchronized methods and synchronized statements to prevent two clients from opening, closing, or modifying the same account at the same time.

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