Interface Condition
In dynamic systems, such as OSGi, one of the more challenging problems can be to define when a system or part of it is ready to do work. The answer can change depending on the individual perspective. The developer of a web server might say, the system is ready when the server starts listening on port 80. An application developer however would define the system as ready when the database connection is up and all servlets are registered. Taking the application developers view, the web server should start listening on port 80 when the application is ready and not beforehand.
The Condition service interface is a marker interface designed to
address this issue. Its role is to provide a dependency that can be tracked.
It acts as a defined signal to other services.
A Condition service must be registered with the
CONDITION_ID service property.
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Field Summary
Fields
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Field Details
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CONDITION_ID
Service property identifying a condition's unique identifier.Since a
Conditionservice can potentially describe more then one condition, the type of this service property isString+.- See Also:
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CONDITION_ID_TRUE
The unique identifier for the default True condition.The default True condition is registered by the framework during framework initialization and therefore can always be relied upon.
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INSTANCE
A condition instance that can be used to registerConditionservices.This can be helpful to avoid a bundle having to implement this interface to register a
Conditionservice
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