resourcemanager.java

分布式数据库原形代码 可以支持个用户同时登陆到数据库中查询需要的资源

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";

}