package transaction;import java.rmi.*;/**  * Interface for a simple Resource Manager for the Distributed Travel * Reservation System. * <p> * Failure reporting is done using two pieces, exceptions and boolean * return values.  Exceptions are used for systemy things - like * transactions that were forced to abort, or don't exist.  Return * values are used for operations that would affect the consistency of * the database, like the deletion of more cars than the database * knows about. * <p> * If there is a boolean return value and you're not sure how it would * be used in your implementation, ignore it.  We used boolean return * values in the interface generously to allow flexibility in * implementation.  But don't forget to return true when the operation * has succeeded. * <p> * All methods in the interface are declared to throw RemoteException. * This exception is thrown by the RMI system during a remote method * call to indicate that either a communication failure or a protocol * error has occurred. Your RM code will never have to directly throw * this exception, but any client code that you write must catch the * exception and take the appropriate action. */public interface ResourceManager extends Remote {    //////////    // TRANSACTION INTERFACE    //////////    /**     * Start a new transaction, and return its transaction id.     *     * @return A unique transaction ID > 0.     *     * @throws RemoteException on communications failure.     */    public int start() 	throws RemoteException;     /**     * Commit transaction.     *     * @param xid id of transaction to be committed.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean commit(int xid) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /**     * Abort transaction.     *     * @param xid id of transaction to be aborted.     *     * @throws RemoteException on communications failure.     * @throws InvalidTransactionException if transaction id is invalid.     */    public void abort(int xid) 	throws RemoteException, 	       InvalidTransactionException;         //////////    // ADMINISTRATIVE INTERFACE    //////////    /**     * Add seats to a flight.  In general this will be used to create     * a new flight, but it should be possible to add seats to an     * existing flight.  Adding to an existing flight should overwrite     * the current price of the available seats.     *     * @param xid id of transaction.     * @param flightNum flight number, cannot be null.     * @param numSeats number of seats to be added to the flight.     * @param price price of each seat. If price < 0,     *                    don't overwrite the current price.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean addFlight(int xid, String flightNum, int numSeats, int price) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /**     * Delete an entire flight.     * Implies whole deletion of the flight: all seats, all reservations.     * Should fail if a customer has a reservation on this flight.     *     * @param xid id of transaction.     * @param flightNum flight number, cannot be null.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean deleteFlight(int xid, String flightNum) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;         /**     * Add rooms to a location.       * This should look a lot like addFlight, only keyed on a location     * instead of a flight number.     *     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     *     * @see #addFlight     */    public boolean addRooms(int xid, String location, int numRooms, int price) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;    /**     * Delete rooms from a location.     * This subtracts from the available room count (rooms not allocated     * to a customer).  It should fail if it would make the count of     * available rooms negative.     *     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     *     * @see #deleteFlight     */    public boolean deleteRooms(int xid, String location, int numRooms) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;         /**      * Add cars to a location.     * Cars have the same semantics as hotels (see addRooms).     *      * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     *     * @see #addRooms     * @see #addFlight     */    public boolean addCars(int xid, String location, int numCars, int price) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /**     * Delete cars from a location.     * Cars have the same semantics as hotels.     *     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     *     * @see #deleteRooms     * @see #deleteFlight     */    public boolean deleteCars(int xid, String location, int numCars) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;         /**      * Add a new customer to database.  Should return success if     * customer already exists.     *      * @param xid id of transaction.     * @param custName name of customer.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean newCustomer(int xid, String custName) 	throws RemoteException,	       TransactionAbortedException,	       InvalidTransactionException;     /**     * Delete this customer and associated reservations.     *     * @param xid id of transaction.     * @param custName name of customer.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean deleteCustomer(int xid, String custName) 	throws RemoteException,	       TransactionAbortedException,	       InvalidTransactionException;     //////////    // QUERY INTERFACE    //////////    /**     * Return the number of empty seats on a flight.     *     * @param xid id of transaction.     * @param flightNum flight number.     * @return # empty seats on the flight.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public int queryFlight(int xid, String flightNum) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /** Return the price of a seat on this flight. */    public int queryFlightPrice(int xid, String flightNum) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /** Return the number of rooms available at a location. */    public int queryRooms(int xid, String location)	throws RemoteException,	       TransactionAbortedException,	       InvalidTransactionException;    /** Return the price of rooms at this location. */    public int queryRoomsPrice(int xid, String location) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /** Return the number of cars available at a location. */    public int queryCars(int xid, String location) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /** Return the price of rental cars at this location. */    public int queryCarsPrice(int xid, String location) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /* Return the total price of all reservations held for a customer. */    public int queryCustomerBill(int xid, String custName)	    throws RemoteException,		   TransactionAbortedException,		   InvalidTransactionException;        //////////    // RESERVATION INTERFACE    //////////    /**     * Reserve a flight on behalf of this customer.     *     * @param xid id of transaction.     * @param custName name of customer.     * @param flightNum flight number.     * @return true on success, false on failure.     *     * @throws RemoteException on communications failure.     * @throws TransactionAbortedException if transaction was aborted.     * @throws InvalidTransactionException if transaction id is invalid.     */    public boolean reserveFlight(int xid, String custName, String flightNum) 	throws RemoteException,	       TransactionAbortedException,	       InvalidTransactionException;    /** Reserve a car for this customer at the specified location. */    public boolean reserveCar(int xid, String custName, String location) 	throws RemoteException, 	       TransactionAbortedException,	       InvalidTransactionException;     /** Reserve a room for this customer at the specified location. */    public boolean reserveRoom(int xid, String custName, String location) 	throws RemoteException,	       TransactionAbortedException,	       InvalidTransactionException;    //////////    // TECHNICAL/TESTING INTERFACE    //////////    /**      * Shutdown gracefully. Stop accepting new transactions, wait for     * running transactions to terminate, and clean up disk state.     * When this RM restarts, it should not attempt to recover its     * state if the client called shutdown to terminate it.     *     * @return true on success, false on failure.     * @throws RemoteException on communications failure.     */    public boolean shutdown() 	throws RemoteException;    /**      * Call exit immediately.  Used to simulate a system failure such     * as a power outage.     * <p>     * This method is used for testing and is not part of a transaction.     *     * @return true on success, false on failure.     */    public boolean dieNow() 	throws RemoteException;    /**      * Sets a flag so that the RM fails in the middle of the next     * commit operation.  Specifically, using shadow paging, you     * should call System.exit() after the updated tables have been     * written to disk, but just BEFORE you switch the on-disk pointer     * to point to this new copy.  (Convince yourself that the     * transaction is effectively aborted.)     * <p>     * This method is used for testing and is not part of a transaction.     *     * @return true on success, false on failure.     */    public boolean dieBeforePointerSwitch() 	throws RemoteException;    /**      * Sets a flag so that the RM fails in the middle of the next     * commit operation.  Unlike the above, however, the RM exits     * AFTER the on-disk pointer is updated, but before the commit     * call could return to the caller.  Make sure that, when the RM     * recovers, the transaction is seen as committed.     * <p>     * This method is used for testing and is not part of a transaction.     *     * @return true on success, false on failure.     */    public boolean dieAfterPointerSwitch() 	throws RemoteException;    /** The default RMI name a ResourceManager uses to bind. */    public final String DefaultRMIName = "RM";}