The SharedObject class is used to read and store limited amounts of data on a user's computer or on a server. Shared objects offer real-time data sharing between multiple client SWF files and objects that are persistent on the local computer or remote server. Local shared objects are similar to browser cookies and remote shared objects are similar to real-time data transfer devices. To use remote shared objects, you need Adobe Flash Media Server.
Use shared objects to do the following:
SharedObject.getLocal()to create a shared object in an application, such as a calculator with memory. When the user closes the calculator, Flash Player saves the last value in a shared object on the user's computer. The next time the calculator is run, it contains the values it had previously. Alternatively, if you set the shared object's properties to
nullbefore the calculator application is closed, the next time the application runs, it opens without any values. Another example of maintaining local persistence is tracking user preferences or other data for a complex website, such as a record of which articles a user read on a news site. Tracking this information allows you to display articles that have already been read differently from new, unread articles. Storing this information on the user's computer reduces server load.
SharedObject.getRemote()to create a remote shared object, such as a phone list, that is persistent on the server. Whenever a client makes changes to the shared object, the revised data is available to all clients currently connected to the object or who later connect to it. If the object is also persistent locally, and a client changes data while not connected to the server, the data is copied to the remote shared object the next time the client connects to the object.
To create a local shared object, call
SharedObject.getLocal(). To create a remote shared object,
When an application closes, shared objects are flushed, or
written to a disk. You can also call the
flush() method to
explicitly write data to a disk.
Local disk space considerations. Local shared objects have some limitations that are important to consider as you design your application. Sometimes SWF files may not be allowed to write local shared objects, and sometimes the data stored in local shared objects can be deleted without your knowledge. Flash Player users can manage the disk space that is available to individual domains or to all domains. When users decrease the amount of disk space available, some local shared objects may be deleted. Flash Player users also have privacy controls that can prevent third-party domains(domains other than the domain in the current browser address bar) from reading or writing local shared objects.
Note: SWF files that are stored and run on a local computer, not from a remote server, can always write third-party shared objects to disk. For more information about third-party shared objects, see the Global Storage Settings panel in Flash Player Help.
It's a good idea to check for failures related to the amount of disk
space and to user privacy controls. Perform these checks when you call
SharedObject.getLocal()- Flash Player throws an exception when a call to this method fails, such as when the user has disabled third-party shared objects and the domain of your SWF file does not match the domain in the browser address bar.
SharedObject.flush()- Flash Player throws an exception when a call to this method fails. It returns
SharedObjectFlushStatus.FLUSHEDwhen it succeeds. It returns
SharedObjectFlushStatus.PENDINGwhen additional storage space is needed. Flash Player prompts the user to allow an increase in storage space for locally saved information. Thereafter, the
netStatusevent is dispatched with an information object indicating whether the flush failed or succeeded.
If your SWF file attempts to create or modify local shared objects, make
sure that your SWF file is at least 215 pixels wide and at least 138 pixels
high(the minimum dimensions for displaying the dialog box that prompts
users to increase their local shared object storage limit). If your SWF
file is smaller than these dimensions and an increase in the storage limit
SharedObject.flush() fails, returning
SharedObjectFlushedStatus.PENDING and dispatching the
Remote shared objects. With Flash Media Server, you can create and use remote shared objects, that are shared in real-time by all clients connected to your application. When one client changes a property of a remote shared object, the property is changed for all connected clients. You can use remote shared objects to synchronize clients, for example, users in a multi-player game.
Each remote shared object has a
data property which is an
Object with properties that store data. Call
change an property of the data object. The server updates the properties,
sync event, and sends the properties back to the
You can choose to make remote shared objects persistent on the client, the server, or both. By default, Flash Player saves locally persistent remote shared objects up to 100K in size. When you try to save a larger object, Flash Player displays the Local Storage dialog box, which lets the user allow or deny local storage for the shared object. Make sure your Stage size is at least 215 by 138 pixels; this is the minimum size Flash requires to display the dialog box.
If the user selects Allow, the server saves the shared object and
netStatus event with a
SharedObject.Flush.Success. If the user select Deny, the
server does not save the shared object and dispatches a
netStatus event with a
code property of
Aggregates an instance of the EventDispatcher class.
The EventDispatcher class is generally used as a base class, which means that most developers do not need to use this constructor function. However, advanced developers who are implementing the IEventDispatcher interface need to use this constructor. If you are unable to extend the EventDispatcher class and must instead implement the IEventDispatcher interface, use this constructor to aggregate an instance of the EventDispatcher class.
The target object for events dispatched to the EventDispatcher object. This parameter is used when the EventDispatcher instance is aggregated by a class that implements IEventDispatcher; it is necessary so that the containing object can be the target for events. Do not use this parameter in simple cases in which a class extends EventDispatcher.
The collection of attributes assigned to the
data property of
the object; these attributes can be shared and stored. Each attribute can
Boolean, ByteArray, XML, and so on. For example, the following lines
assign values to various aspects of a shared object:
For remote shared objects used with a server, all attributes of the
data property are available to all clients connected to the
shared object, and all attributes are saved if the object is persistent.
If one client changes the value of an attribute, all clients now see the
The current size of the shared object, in bytes.
Flash calculates the size of a shared object by stepping through all of its data properties; the more data properties the object has, the longer it takes to estimate its size. Estimating object size can take significant processing time, so you may want to avoid using this method unless you have a specific need for it.
Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event. You can register event listeners on all nodes in the display list for a specific type of event, phase, and priority.
After you successfully register an event listener, you cannot change
its priority through additional calls to
To change a listener's priority, you must first call
removeListener(). Then you can register the listener again
with the new priority level.
Keep in mind that after the listener is registered, subsequent calls to
addEventListener() with a different
useCapture value result in the creation of a separate
listener registration. For example, if you first register a listener with
useCapture set to
true, it listens only during
the capture phase. If you call
addEventListener() again using
the same listener object, but with
useCapture set to
false, you have two separate listeners: one that listens
during the capture phase and another that listens during the target and
You cannot register an event listener for only the target phase or the bubbling phase. Those phases are coupled during registration because bubbling applies only to the ancestors of the target node.
If you no longer need an event listener, remove it by calling
removeEventListener(), or memory problems could result. Event
listeners are not automatically removed from memory because the garbage
collector does not remove the listener as long as the dispatching object
useWeakReference parameter is set to
Copying an EventDispatcher instance does not copy the event listeners attached to it.(If your newly created node needs an event listener, you must attach the listener after creating the node.) However, if you move an EventDispatcher instance, the event listeners attached to it move along with it.
If the event listener is being registered on a node while an event is being processed on this node, the event listener is not triggered during the current phase but can be triggered during a later phase in the event flow, such as the bubbling phase.
If an event listener is removed from a node while an event is being processed on the node, it is still triggered by the current actions. After it is removed, the event listener is never invoked again(unless registered again for future processing).
The type of event.
Determines whether the listener works in the
capture phase or the target and bubbling phases.
useCapture is set to
true, the listener processes the
event only during the capture phase and not in the
target or bubbling phase. If
listener processes the event only during the
target or bubbling phase. To listen for the event
in all three phases, call
addEventListener twice, once with
useCapture set to
then again with
useCapture set to
The priority level of the event listener. The priority is designated by a signed 32-bit integer. The higher the number, the higher the priority. All listeners with priority n are processed before listeners of priority n-1. If two or more listeners share the same priority, they are processed in the order in which they were added. The default priority is 0.
Determines whether the reference to the listener is strong or weak. A strong reference(the default) prevents your listener from being garbage-collected. A weak reference does not.
Class-level member functions are not subject to garbage collection, so you can set `useWeakReference` to `true` for class-level member functions without subjecting them to garbage collection. If you set `useWeakReference` to `true` for a listener that is a nested inner function, the function will be garbage-collected and no longer persistent. If you create references to the inner function(save it in another variable) then it is not garbage-collected and stays persistent.
For local shared objects, purges all of the data and deletes the shared object from the disk. The reference to the shared object is still active, but its data properties are deleted.
For remote shared objects used with Flash Media Server,
clear() disconnects the object and purges all of the data. If
the shared object is locally persistent, this method also deletes the
shared object from the disk. The reference to the shared object is still
active, but its data properties are deleted.
Dispatches an event into the event flow. The event target is the
EventDispatcher object upon which the
The Event object that is dispatched into the event flow. If
the event is being redispatched, a clone of the event is
created automatically. After an event is dispatched, its
target property cannot be changed, so you must
create a new copy of the event for redispatching to work.
A value of
true if the event was successfully
dispatched. A value of
false indicates failure or
preventDefault() was called on the event.
Immediately writes a locally persistent shared object to a local file. If
you don't use this method, Flash Player writes the shared object to a file
when the shared object session ends - that is, when the SWF file is
closed, when the shared object is garbage-collected because it no longer
has any references to it, or when you call
If this method returns
Flash Player displays a dialog box asking the user to increase the amount
of disk space available to objects from this domain. To allow space for
the shared object to grow when it is saved in the future, which avoids
return values of
PENDING, pass a value for
minDiskSpace. When Flash Player tries to write the file, it
looks for the number of bytes passed to
of looking for enough space to save the shared object at its current size.
For example, if you expect a shared object to grow to a maximum size of
500 bytes, even though it might start out much smaller, pass 500 for
minDiskSpace. If Flash asks the user to allot disk space for
the shared object, it asks for 500 bytes. After the user allots the
requested amount of space, Flash won't have to ask for more space on
future attempts to flush the object(as long as its size doesn't exceed
After the user responds to the dialog box, this method is called again.
netStatus event is dispatched with a
The minimum disk space, in bytes, that must be allotted for this object.
Either of the following values:
* `SharedObjectFlushStatus.PENDING`: The user has permitted local information storage for objects from this domain, but the amount of space allotted is not sufficient to store the object. Flash Player prompts the user to allow more space. To allow space for the shared object to grow when it is saved, thus avoiding a `SharedObjectFlushStatus.PENDING` return value, pass a value for `minDiskSpace`. * `SharedObjectFlushStatus.FLUSHED`: The shared object has been successfully written to a file on the local disk.
Checks whether the EventDispatcher object has any listeners registered for
a specific type of event. This allows you to determine where an
EventDispatcher object has altered handling of an event type in the event
flow hierarchy. To determine whether a specific event type actually
triggers an event listener, use
The difference between
willTrigger() is that
examines only the object to which it belongs, whereas
willTrigger() examines the entire event flow for the event
specified by the
hasEventListener() is called from a LoaderInfo
object, only the listeners that the caller can access are considered.
The type of event.
A value of
true if a listener of the specified type
Removes a listener from the EventDispatcher object. If there is no matching listener registered with the EventDispatcher object, a call to this method has no effect.
The type of event.
Specifies whether the listener was registered for the
capture phase or the target and bubbling phases. If the
listener was registered for both the capture phase and
the target and bubbling phases, two calls to
removeEventListener() are required to
remove both, one call with
true, and another call with
useCapture() set to
Checks whether an event listener is registered with this EventDispatcher
object or any of its ancestors for the specified event type. This method
true if an event listener is triggered during any
phase of the event flow when an event of the specified type is dispatched
to this EventDispatcher object or any of its descendants.
The difference between the
hasEventListener() and the
willTrigger() methods is that
examines only the object to which it belongs, whereas the
willTrigger() method examines the entire event flow for the
event specified by the
willTrigger() is called from a LoaderInfo object,
only the listeners that the caller can access are considered.
The type of event.
A value of
true if a listener of the specified type
will be triggered;
Returns a reference to a locally persistent shared object that is only
available to the current client. If the shared object does not already
exist, this method creates one. If any values passed to
getLocal() are invalid or if the call fails, Flash Player
throws an exception.
The following code shows how you assign the returned shared object reference to a variable:
Note: If the user has chosen to never allow local storage for
this domain, the object is not saved locally, even if a value for
localPath is specified. The exception to this rule is local
content. Local content can always write shared objects from third-party
domains(domains other than the domain in the current browser address bar)
to disk, even if writing of third-party shared objects to disk is
To avoid name conflicts, Flash looks at the location of the SWF file
creating the shared object. For example, if a SWF file at
www.myCompany.com/apps/stockwatcher.swf creates a shared object named
portfolio, that shared object does not conflict with another
portfolio that was created by a SWF file at
www.yourCompany.com/photoshoot.swf because the SWF files originate from
localPath parameter is optional, you should
give some thought to its use, especially if other SWF files need to access
the shared object. If the data in the shared object is specific to one SWF
file that will not be moved to another location, then use of the default
value makes sense. If other SWF files need access to the shared object, or
if the SWF file that creates the shared object will later be moved, then
the value of this parameter affects how accessible the shared object will
be. For example, if you create a shared object with
set to the default value of the full path to the SWF file, no other SWF
file can access that shared object. If you later move the original SWF
file to another location, not even that SWF file can access the data
already stored in the shared object.
To avoid inadvertently restricting access to a shared object, use the
localpath parameter. The most permissive approach is to set
/(slash), which makes the shared
object available to all SWF files in the domain, but increases the
likelihood of name conflicts with other shared objects in the domain. A
more restrictive approach is to append
localPath with folder
names that are in the full path to the SWF file. For example, for a
portfolio shared object created by the SWF file at
www.myCompany.com/apps/stockwatcher.swf, you could set the
localPath parameter to
/apps/stockwatcher.swf. You must determine which approach
provides optimal flexibility for your application.
When using this method, consider the following security model:
Suppose you publish SWF file content to be played back as local files (either locally installed SWF files or EXE files), and you need to access a specific shared object from more than one local SWF file. In this situation, be aware that for local files, two different locations might be used to store shared objects. The domain that is used depends on the security permissions granted to the local file that created the shared object. Local files can have three different levels of permissions:
Local files with access to the local filesystem(level 1 or 3) store their shared objects in one location. Local files without access to the local filesystem(level 2) store their shared objects in another location.
You can prevent a SWF file from using this method by setting the
allowNetworking parameter of the the
embed tags in the HTML page that contains the SWF
For more information, see the Flash Player Developer Center Topic: Security.
The name of the object. The name can include forward
/); for example,
work/addresses is a legal name. Spaces are
not allowed in a shared object name, nor are the
~ % & \
; : " ' , < > ? #
The full or partial path to the SWF file that created the shared object, and that determines where the shared object will be stored locally. If you do not specify this parameter, the full path is used.
Determines whether access to this shared object is restricted to SWF files that are delivered over an HTTPS connection. If your SWF file is delivered over HTTPS, this parameter's value has the following effects:
* If this parameter is set to `true`, Flash Player creates a new secure shared object or gets a reference to an existing secure shared object. This secure shared object can be read from or written to only by SWF files delivered over HTTPS that call `SharedObject.getLocal()` with the `secure` parameter set to `true`. * If this parameter is set to `false`, Flash Player creates a new shared object or gets a reference to an existing shared object that can be read from or written to by SWF files delivered over non-HTTPS connections. If your SWF file is delivered over a non-HTTPS connection and you try to set this parameter to `true`, the creation of a new shared object (or the access of a previously created secure shared object) fails and `null` is returned. Regardless of the value of this parameter, the created shared objects count toward the total amount of disk space allowed for a domain. The following diagram shows the use of the `secure` parameter:
A reference to a shared object that is persistent locally and is
available only to the current client. If Flash Player can't create
or find the shared object(for example, if
was specified but no such directory exists), this method throws an
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