net.jini.space
Interface JavaSpace

public abstract interface JavaSpace

This interface is implemented by servers that export a JavaSpaces(TM) technology service. The operations in this interface are the public methods that all such spaces support.

See Also:

Entry

Field Summary

static long

NO_WAIT Wait for no time at all.

Method Summary

EventRegistration	notify(Entry tmpl, Transaction txn, RemoteEventListener listener, long lease, java.rmi.MarshalledObject handback) When entries are written that match this template notify the given listener with a RemoteEvent that includes the handback object.
Entry	read(Entry tmpl, Transaction txn, long timeout) Read any matching entry from the space, blocking until one exists.
Entry	readIfExists(Entry tmpl, Transaction txn, long timeout) Read any matching entry from the space, returning null if there is currently is none.
Entry	snapshot(Entry e) Return a snapshot of the given entry.
Entry	take(Entry tmpl, Transaction txn, long timeout) Take a matching entry from the space, waiting until one exists.
Entry	takeIfExists(Entry tmpl, Transaction txn, long timeout) Take a matching entry from the space, returning null if there is currently is none.
Lease	write(Entry entry, Transaction txn, long lease) Write a new entry into the space.

Field Detail

NO_WAIT

public static final long NO_WAIT

Wait for no time at all. This is used as a timeout value in various read and take calls.

See Also:

read(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long), readIfExists(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long), take(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long), takeIfExists(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long)

Method Detail

write

public Lease write(Entry entry,
                   Transaction txn,
                   long lease)
            throws TransactionException,
                   java.lang.SecurityException,
                   java.rmi.RemoteException

Write a new entry into the space.

Throws:

TransactionException - A transaction error occurred

read

public Entry read(Entry tmpl,
                  Transaction txn,
                  long timeout)
           throws UnusableEntryException,
                  TransactionException,
                  java.lang.SecurityException,
                  java.lang.InterruptedException,
                  java.rmi.RemoteException

Read any matching entry from the space, blocking until one exists. Return null if the timeout expires.

Parameters:

tmpl - The template used for matching. Matching is done against tmpl with blank fields being wildcards ("match anything") other fields being values ("match exactly on the serialized form").

txn - The transaction (if any) under which to work.

timeout - How long the client is willing to wait for a transactionally proper matching entry. A timeout of NO_WAIT means to wait no time at all; this is equivalent to a wait of zero.

Throws:

TransactionException - A transaction error occurred

readIfExists

public Entry readIfExists(Entry tmpl,
                          Transaction txn,
                          long timeout)
                   throws UnusableEntryException,
                          TransactionException,
                          java.lang.SecurityException,
                          java.lang.InterruptedException,
                          java.rmi.RemoteException

Read any matching entry from the space, returning null if there is currently is none. Matching and timeouts are done as in read, except that blocking in this call is done only if necessary to wait for transactional state to settle.

Throws:

TransactionException - A transaction error occurred

See Also:

read(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long)

take

public Entry take(Entry tmpl,
                  Transaction txn,
                  long timeout)
           throws UnusableEntryException,
                  TransactionException,
                  java.lang.SecurityException,
                  java.lang.InterruptedException,
                  java.rmi.RemoteException

Take a matching entry from the space, waiting until one exists. Matching is and timeout done as for read.

Throws:

TransactionException - A transaction error occurred

See Also:

read(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long)

takeIfExists

public Entry takeIfExists(Entry tmpl,
                          Transaction txn,
                          long timeout)
                   throws UnusableEntryException,
                          TransactionException,
                          java.lang.SecurityException,
                          java.lang.InterruptedException,
                          java.rmi.RemoteException

Take a matching entry from the space, returning null if there is currently is none. Matching is and timeout done as for read, except that blocking in this call is done only if necessary to wait for transactional state to settle.

Throws:

TransactionException - A transaction error occurred

See Also:

read(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long)

notify

public EventRegistration notify(Entry tmpl,
                                Transaction txn,
                                RemoteEventListener listener,
                                long lease,
                                java.rmi.MarshalledObject handback)
                         throws TransactionException,
                                java.lang.SecurityException,
                                java.rmi.RemoteException

When entries are written that match this template notify the given listener with a RemoteEvent that includes the handback object. Matching is done as for read.

See Also:

read(net.jini.core.entry.Entry, net.jini.core.transaction.Transaction, long), EventRegistration

snapshot

public Entry snapshot(Entry e)
               throws java.rmi.RemoteException

Return a snapshot of the given entry. The snapshot can be used anywhere the original entry can be, and will maintain the same value as the original entry, even if the entry is modified after the snapshot is taken. The implementation of the JavaSpace interface the snapshot more efficient to use than repeated uses of the original entry.

Using a snapshot with a different space than the one that produced it yields unpredictable results.