RTI Connext Java API Version 7.1.0

Kinds of communication status. More...


class  StatusKind
 Type for status kinds. More...


static final int STATUS_MASK_NONE
 No bits are set. More...
static final int STATUS_MASK_ALL
 All bits are set. More...

Detailed Description

Kinds of communication status.

QoS Policies

Each concrete com.rti.dds.infrastructure.Entity is associated with a set of Status objects whose value represents the communication status of that entity. Each status value can be accessed with a corresponding method on the com.rti.dds.infrastructure.Entity.

When these status values change, the corresponding com.rti.dds.infrastructure.StatusCondition objects are activated and the proper com.rti.dds.infrastructure.Listener objects are invoked to asynchronously inform the application.

An application is notified of communication status by means of the com.rti.dds.infrastructure.Listener or the com.rti.dds.infrastructure.WaitSet / com.rti.dds.infrastructure.Condition mechanism. The two mechanisms may be combined in the application (e.g., using com.rti.dds.infrastructure.WaitSet (s) / com.rti.dds.infrastructure.Condition (s) to access the data and com.rti.dds.infrastructure.Listener (s) to be warned asynchronously of erroneous communication statuses).

It is likely that the application will choose one or the other mechanism for each particular communication status (not both). However, if both mechanisms are enabled, then the com.rti.dds.infrastructure.Listener mechanism is used first and then the com.rti.dds.infrastructure.WaitSet objects are signalled.

The statuses may be classified into:

Read communication statuses are treated slightly differently than the others because they don't change independently. In other words, at least two changes will appear at the same time (com.rti.dds.infrastructure.StatusKind.StatusKind.DATA_ON_READERS_STATUS and com.rti.dds.infrastructure.StatusKind.StatusKind.DATA_AVAILABLE_STATUS) and even several of the last kind may be part of the set. This 'grouping' has to be communicated to the application.

For each plain communication status, there is a corresponding structure to hold the status value. These values contain the information related to the change of status, as well as information related to the statuses themselves (e.g., contains cumulative counts).

"Status Values"

Changes in Status

Associated with each one of an com.rti.dds.infrastructure.Entity's communication status is a logical StatusChangedFlag. This flag indicates whether that particular communication status has changed since the last time the status was read by the application. The way the status changes is slightly different for the Plain Communication Status and the Read Communication status.

"\p StatusChangedFlag indicates if status has changed"

Changes in plain communication status

For the plain communication status, the StatusChangedFlag flag is initially set to FALSE. It becomes TRUE whenever the plain communication status changes and it is reset to com.rti.dds.infrastructure.false each time the application accesses the plain communication status via the proper get_<plain communication status>() operation on the com.rti.dds.infrastructure.Entity.

The communication status is also reset to FALSE whenever the associated listener operation is called as the listener implicitly accesses the status which is passed as a parameter to the operation. The fact that the status is reset prior to calling the listener means that if the application calls the get_<plain communication status> from inside the listener it will see the status already reset.

An exception to this rule is when the associated listener is the 'nil' listener. The 'nil' listener is treated as a NOOP and the act of calling the 'nil' listener does not reset the communication status.

For example, the value of the StatusChangedFlag associated with the com.rti.dds.infrastructure.StatusKind.StatusKind.REQUESTED_DEADLINE_MISSED_STATUS will become TRUE each time new deadline occurs (which increases com.rti.dds.subscription.RequestedDeadlineMissedStatus.total_count). The value changes to FALSE when the application accesses the status via the corresponding com.rti.dds.subscription.DataReader.get_requested_deadline_missed_status method on the proper Entity

"Changes in \p StatusChangedFlag for plain communication status"

Changes in read communication status

For the read communication status, the StatusChangedFlag flag is initially set to FALSE. The StatusChangedFlag becomes TRUE when either a data-sample arrives or else the com.rti.dds.subscription.ViewStateKind, com.rti.dds.subscription.SampleStateKind, or com.rti.dds.subscription.InstanceStateKind of any existing sample changes for any reason other than a call to com.rti.ndds.example.FooDataReader.read, com.rti.ndds.example.FooDataReader.take or their variants. Specifically any of the following events will cause the StatusChangedFlag to become TRUE:

Depending on the kind of StatusChangedFlag, the flag transitions to FALSE again as follows:

"Changes in \p StatusChangedFlag for read communication status"

See also
com.rti.dds.infrastructure.WaitSet, com.rti.dds.infrastructure.Condition

Variable Documentation



No bits are set.



All bits are set.