ViewStateKind Class Reference
[View States]

Indicates whether or not an instance is new. More...

List of all members.

Static Public Attributes
static final int	NEW_VIEW_STATE = 0x0001 << 0
	New instance. This latest generation of the instance has not previously been accessed.
static final int	NOT_NEW_VIEW_STATE = 0x0001 << 1
	Not a new instance. This latest generation of the instance has previously been accessed.
static final int	ANY_VIEW_STATE = 0xffff
	Any view state ViewStateKind.NEW_VIEW_STATE | ViewStateKind.NOT_NEW_VIEW_STATE.

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Detailed Description

Indicates whether or not an instance is new.

For each instance (identified by the key), the middleware internally maintains a view state relative to each com.rti.dds.subscription.DataReader. The view state can be either:

• ViewStateKind.NEW_VIEW_STATE indicates that either this is the first time that the com.rti.dds.subscription.DataReader has ever accessed samples of that instance, or else that the com.rti.dds.subscription.DataReader has accessed previous samples of the instance, but the instance has since been reborn (i.e. become not-alive and then alive again). These two cases are distinguished by examining the com.rti.dds.subscription.SampleInfo.disposed_generation_count and the com.rti.dds.subscription.SampleInfo.no_writers_generation_count.

• ViewStateKind.NOT_NEW_VIEW_STATE indicates that the com.rti.dds.subscription.DataReader has already accessed samples of the same instance and that the instance has not been reborn since.

The view_state available in the com.rti.dds.subscription.SampleInfo is a snapshot of the view state of the instance relative to the com.rti.dds.subscription.DataReader used to access the samples at the time the collection was obtained (i.e. at the time read or take was called). The view_state is therefore the same for all samples in the returned collection that refer to the same instance.

Once an instance has been detected as not having any "live" writers and all the samples associated with the instance are "taken" from the com.rti.dds.subscription.DataReader, the middleware can reclaim all local resources regarding the instance. Future samples will be treated as "never seen."

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Member Data Documentation

final int NEW_VIEW_STATE = 0x0001 << 0 [static]

New instance. This latest generation of the instance has not previously been accessed.

final int NOT_NEW_VIEW_STATE = 0x0001 << 1 [static]

Not a new instance. This latest generation of the instance has previously been accessed.