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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA.
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<title>NSDistributedNotificationCenter class reference</title>
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$Date: 2002/03/10 08:08:11 $ $Revision: 1.21 $
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$Date: 2005/02/22 11:22:44 $ $Revision: 1.36 $
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#include <base/preface.h>
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#include <Foundation/NSObject.h>
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#include <Foundation/NSConnection.h>
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#include <Foundation/NSDistantObject.h>
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#include <Foundation/NSException.h>
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#include <Foundation/NSArchiver.h>
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#include <Foundation/NSNotification.h>
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#include <Foundation/NSDate.h>
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#include <Foundation/NSPathUtilities.h>
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#include <Foundation/NSRunLoop.h>
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#include <Foundation/NSTask.h>
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#include <Foundation/NSDistributedNotificationCenter.h>
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#include <Foundation/NSUserDefaults.h>
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#include <Foundation/NSHost.h>
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#include "GNUstepBase/preface.h"
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#include "Foundation/NSObject.h"
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#include "Foundation/NSConnection.h"
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#include "Foundation/NSDistantObject.h"
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#include "Foundation/NSException.h"
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#include "Foundation/NSArchiver.h"
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#include "Foundation/NSNotification.h"
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#include "Foundation/NSDate.h"
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#include "Foundation/NSPathUtilities.h"
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#include "Foundation/NSRunLoop.h"
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#include "Foundation/NSTask.h"
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#include "Foundation/NSDistributedNotificationCenter.h"
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#include "Foundation/NSUserDefaults.h"
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#include "Foundation/NSHost.h"
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#include "Foundation/NSPortNameServer.h"
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#include "../Tools/gdnc.h"
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* Macros to build text to start name server and to give an error
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* message about it - they include installation path information.
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#define MAKE_GDNC_CMD [GSSystemRootDirectory() \
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stringByAppendingPathComponent: @"Tools/gdnc"]
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#define MAKE_GDNC_ERR [NSString stringWithFormat: \
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@"check that %@/Tools/gdnc is running", \
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GSSystemRootDirectory()]
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* Global variables for distributed notification center types.
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NSString *NSLocalNotificationCenterType =
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@"NSLocalNotificationCenterType";
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@interface NSDistributedNotificationCenter (Private)
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to: (unsigned long)observer;
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* <p>The <code>NSDistributedNotificationCenter</code> provides a versatile yet
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* simple mechanism for objects in different processes to communicate
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* effectively while knowing very little about each others' internals.<br />
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* A distributed notification center acts much like a normal
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* notification center, but it handles notifications on a machine-wide
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* (or local network wide) basis rather than just notifications within
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* a single process. Objects are able to register themselves as
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* observers for particular notification names and objects, and they
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* will then receive notifications (including optional user information
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* consisting of a dictionary of property-list objects) as they are posted.
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* <p>Since posting of distributed notifications involves inter-process
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* (and sometimes inter-host) communication, it is fundamentally slower
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* than normal notifications, and should be used relatively sparingly.
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* In order to help with this, the <code>NSDistributedNotificationCenter</code>
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* provides a notion of 'suspension', whereby a center can be suspended
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* causing notifications for observers in the process where the center
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* was suspended to cease receiving notifications. Observers can
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* specify how notifications are to be handled in this case (queued
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* or discarded) and posters can specify that particular notifications
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* are to be delivered immediately irrespective of suspension.
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* <p>Distributed notifications are mediated by a server process which
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* handles all notifications for a particular center type. In GNUstep
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* this process is the <code>gdnc</code> tool, and when started without special
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* options, a gdnc process acts as the local centre for the host it is
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* running on. When started with the <code>GSNetwork</code> user default set
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* to YES, the <code>gdnc</code> tool acts as a local network wide server (you
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* should only run one copy of <code>gdnc</code> like this on your LAN).<br />
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* The <code>gdnc</code> process should be started at machine boot time, but
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* GNUstep will attempt to start it automatically if it can't find it.
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* <p>MacOS-X currently defines only a notification center for the
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* local host. GNUstep also defines a local network center which can
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* be used from multiple hosts. By default the system sends this to
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* any gdnc process it can find which is configured as a network-wide
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* server, but the <code>GDNCHost</code> user default may be used to specify a
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* particular host to be contacted ... this may be of use where you
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* wish to have logically separate clusters of machines on a shared LAN.
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@implementation NSDistributedNotificationCenter
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static NSDistributedNotificationCenter *defCenter = nil;
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static NSDistributedNotificationCenter *locCenter = nil;
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static NSDistributedNotificationCenter *netCenter = nil;
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+ (id) allocWithZone: (NSZone*)z
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[NSException raise: NSInternalInconsistencyException
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format: @"Should not call +alloc for NSDistributedNotificationCenter"];
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* Returns the default notification center ... a shared notification
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* center for the local host. This is simply a convenience method
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* equivalent to calling +notificationCenterForType: with
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* <code>NSLocalNotificationCenterType</code> as its argument.
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+ (id) defaultCenter
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return [self notificationCenterForType: NSLocalNotificationCenterType];
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* Returns a notification center of the specified type.<br />
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* The <code>NSLocalNotificationCenterType</code> provides a shared access to
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* a notificatiuon center used by processes on the local host.<br />
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* The <code>GSNetworkNotificationCenterType</code> provides a shared access to
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* a notificatiuon center used by processes on the local network.<br />
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* MacOS-X supports only <code>NSLocalNotificationCenterType</code>.
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+ (id) notificationCenterForType: (NSString*)type
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NSAssert([type isEqual: NSLocalNotificationCenterType],
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NSInvalidArgumentException);
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[gnustep_global_lock lock];
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tmp = NSAllocateObject(self, 0, NSDefaultMallocZone());
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defCenter = (NSDistributedNotificationCenter*)[tmp init];
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[gnustep_global_lock unlock];
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[localException raise];
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[gnustep_global_lock unlock];
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if ([type isEqual: NSLocalNotificationCenterType] == YES)
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if (locCenter == nil)
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[gnustep_global_lock lock];
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if (locCenter == nil)
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NSDistributedNotificationCenter *tmp;
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tmp = (NSDistributedNotificationCenter*)
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NSAllocateObject(self, 0, NSDefaultMallocZone());
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tmp->_centerLock = [NSRecursiveLock new];
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tmp->_type = RETAIN(NSLocalNotificationCenterType);
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[gnustep_global_lock unlock];
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[localException raise];
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[gnustep_global_lock unlock];
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else if ([type isEqual: GSNetworkNotificationCenterType] == YES)
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if (netCenter == nil)
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[gnustep_global_lock lock];
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if (netCenter == nil)
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NSDistributedNotificationCenter *tmp;
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tmp = (NSDistributedNotificationCenter*)
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NSAllocateObject(self, 0, NSDefaultMallocZone());
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tmp->_centerLock = [NSRecursiveLock new];
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tmp->_type = RETAIN(GSNetworkNotificationCenterType);
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[gnustep_global_lock unlock];
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[localException raise];
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[gnustep_global_lock unlock];
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[NSException raise: NSInvalidArgumentException
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format: @"Unknown center type (%@)", type];
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return nil; /* NOT REACHED */
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suspensionBehavior: NSNotificationSuspensionBehaviorCoalesce];
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* Adds an observer to the receiver.<br />
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* When a notification matching notificationName and anObject is
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* sent to the center, the object anObserver is sent the message
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* aSelector with the notification info dictionary as its argument.<br />
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* The suspensionBehavior governs how the center deals with notifications
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* when the process to which the notification should be delivered is
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* <term><code>NSNotificationSuspensionBehaviorDrop</code></term>
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* Discards the notification if the observing process is suspended.
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* <term><code>NSNotificationSuspensionBehaviorCoalesce</code></term>
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* Discards previously queued notifications when the observing process
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* is suspended, leaving only the last notification posted in the queue.
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* Delivers this single notification when the process becomes unsuspended.
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* <term><code>NSNotificationSuspensionBehaviorHold</code></term>
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* Queues notifications when the observing process is suspended,
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* delivering all the queued notifications when the process becomes
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* <term><code>NSNotificationSuspensionBehaviorDeliverImmediately</code></term>
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* Deliver the notification immediately, even if the destination
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* process is suspended.
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- (void) addObserver: (id)anObserver
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selector: (SEL)aSelector
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name: (NSString*)notificationName
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* The following dummy class is here solely as a workaround for pre 3.3
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* versions of gcc where protocols didn't work properly unless implemented
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* in the source where the '@protocol()' directive is used.
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@interface NSDistributedNotificationCenterDummy : NSObject <GDNCProtocol>
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- (void) addObserver: (unsigned long)anObserver
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selector: (NSString*)aSelector
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name: (NSString*)notificationname
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object: (NSString*)anObject
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suspensionBehavior: (NSNotificationSuspensionBehavior)suspensionBehavior
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for: (id<GDNCClient>)client;
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- (oneway void) postNotificationName: (NSString*)notificationName
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object: (NSString*)anObject
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deliverImmediately: (BOOL)deliverImmediately
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for: (id<GDNCClient>)client;
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- (void) registerClient: (id<GDNCClient>)client;
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- (void) removeObserver: (unsigned long)anObserver
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name: (NSString*)notificationname
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object: (NSString*)anObject
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for: (id<GDNCClient>)client;
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- (void) setSuspended: (BOOL)flag
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for: (id<GDNCClient>)client;
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- (void) unregisterClient: (id<GDNCClient>)client;
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@implementation NSDistributedNotificationCenterDummy
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- (void) addObserver: (unsigned long)anObserver
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selector: (NSString*)aSelector
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name: (NSString*)notificationname
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object: (NSString*)anObject
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suspensionBehavior: (NSNotificationSuspensionBehavior)suspensionBehavior
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for: (id<GDNCClient>)client
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- (oneway void) postNotificationName: (NSString*)notificationName
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object: (NSString*)anObject
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deliverImmediately: (BOOL)deliverImmediately
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for: (id<GDNCClient>)client
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- (void) registerClient: (id<GDNCClient>)client
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- (void) removeObserver: (unsigned long)anObserver
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name: (NSString*)notificationname
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object: (NSString*)anObject
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for: (id<GDNCClient>)client
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- (void) setSuspended: (BOOL)flag
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for: (id<GDNCClient>)client
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- (void) unregisterClient: (id<GDNCClient>)client
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@implementation NSDistributedNotificationCenter (Private)
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* Establish a connection to the server. This method should only be called
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* when protected by the center's lock, so that it is thread-safe.
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- (void) _connect
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if (_remote == nil)
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NSString *description;
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* Connect to the NSDistributedNotificationCenter for this host.
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host = [[NSUserDefaults standardUserDefaults] stringForKey: @"NSHost"];
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NSString *host = nil;
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NSString *service = nil;
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NSString *description = nil;
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if (_type == NSLocalNotificationCenterType)
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* If we have a host specified, but it is the current host,
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* we do not need to ask for a host by name (nameserver lookup
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* can be faster) and the empty host name can be used to
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* indicate that we may start a gdnc server locally.
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* Connect to the NSDistributedNotificationCenter for this host.
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h = [NSHost hostWithName: host];
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NSLog(@"Unknown -NSHost '%@' ignored", host);
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else if ([h isEqual: [NSHost currentHost]] == YES)
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host = [[NSUserDefaults standardUserDefaults]
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stringForKey: @"NSHost"];
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//host = @"localhost";
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if ([host length] == 0)
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description = @"local host";
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* If we have a host specified, but it is the current host,
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* we do not need to ask for a host by name (nameserver lookup
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* can be faster) and the empty host name can be used to
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* indicate that we may start a <code>gdnc</code> server locally.
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h = [NSHost hostWithName: host];
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NSLog(@"Unknown -NSHost '%@' ignored", host);
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else if ([h isEqual: [NSHost currentHost]] == YES)
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if ([host length] == 0
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|| [host isEqualToString: @"localhost"] == YES
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|| [host isEqualToString: @"127.0.0.1"] == YES)
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description = @"local host";
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service = GDNC_SERVICE;
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else if (_type == GSNetworkNotificationCenterType)
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host = [[NSUserDefaults standardUserDefaults]
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stringForKey: @"GDNCHost"];
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description = host;
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_remote = RETAIN([NSConnection rootProxyForConnectionWithRegisteredName:
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GDNC_SERVICE host: host]);
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if (_remote == nil && [host isEqual: @""] == NO)
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_remote = [NSConnection rootProxyForConnectionWithRegisteredName:
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[GDNC_SERVICE stringByAppendingFormat: @"-%@", host] host: @"*"];
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description = @"network host";
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service = GDNC_NETWORK;
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[NSException raise: NSInternalInconsistencyException
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format: @"Unknown center type - %@", _type];
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if ([host isEqualToString: @"*"] == YES)
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_remote = [NSConnection rootProxyForConnectionWithRegisteredName:
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usingNameServer: [NSSocketPortNameServer sharedInstance]];
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_remote = [NSConnection rootProxyForConnectionWithRegisteredName:
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if (_type == NSLocalNotificationCenterType
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&& _remote == nil && [host isEqual: @""] == NO)
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_remote = [NSConnection rootProxyForConnectionWithRegisteredName:
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[service stringByAppendingFormat: @"-%@", host] host: @"*"];
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static BOOL recursion = NO;
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static BOOL recursion = NO;
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static NSString *cmd = nil;
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static NSArray *args = nil;
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if (recursion == NO)
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static NSString *cmd = nil;
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static NSArray *args = nil;
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NSLog(@"\nI couldn't contact the notification server for %@ -\n"
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@"so I'm attempting to to start one - which will take a few seconds.\n"
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@"It is recommended that you start the notification server (gdnc) either at\n"
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@"login or (better) when your computer is started up.\n", description);
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cmd = RETAIN([[NSSearchPathForDirectoriesInDomains(
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GSToolsDirectory, NSSystemDomainMask, YES) objectAtIndex: 0]
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stringByAppendingPathComponent: @"gdnc"]);
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if ([host length] > 0)
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args = [[NSArray alloc] initWithObjects:
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@"-NSHost", host, nil];
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if (recursion == NO && cmd != nil)
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NSLog(@"\nI couldn't contact the notification server for %@ -\n"
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@"so I'm attempting to to start one - which will take a few seconds.\n"
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@"Trying to launch gdnc from %@ or a machine/operating-system subdirectory.\n"
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@"It is recommended that you start the notification server (gdnc) either at\n"
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@"login or (better) when your computer is started up.\n", description,
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[cmd stringByDeletingLastPathComponent]);
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if (_type == GSNetworkNotificationCenterType)
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args = [[NSArray alloc] initWithObjects:
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@"-GSNetwork", @"YES", nil];
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else if ([host length] > 0)
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args = [[NSArray alloc] initWithObjects:
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@"-NSHost", host, nil];
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[NSTask launchedTaskWithLaunchPath: cmd arguments: args];
added
removed
Source/NSDistributedNotificationCenter.m
