com.diffusiondata.gateway.framework

Interface StateHandler

public interface StateHandler

State Handler.

Each service is provided with a state handler which it can use to report its current status at any time. It may also be used to enquire upon the current state of the service.

A state handler instance is for the exclusive use of the service handler for which it was created and may not be used across services or after the service has been stopped.

Author:

DiffusionData Limited

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	StateHandler.Status Indicates the type of status being reported when using the reportStatus(com.diffusiondata.gateway.framework.StateHandler.Status, java.lang.String, java.lang.String) method.

Method Summary

Modifier and Type	Method and Description
ServiceState	getState() Returns the current state of the service.
CompletableFuture<ServiceState>	reportStatus(StateHandler.Status status, String title, String description) Reports current status.

Method Detail

reportStatus

CompletableFuture<ServiceState> reportStatus(StateHandler.Status status,
                                             String title,
                                             String description)

Reports current status.

This should be used whenever the handler's status changes in some way. For example, if some failure occurs within the handler or the application, which renders the handler inoperative. It can also be used to report that a service is now (at least partly) operational, from the point of view of the application.

Reporting a RED status for an ACTIVE service will cause the framework to assume that the handler is no longer operating normally and the ServiceHandler.pause(com.diffusiondata.gateway.framework.ServiceHandler.PauseReason) method will be called with a reason of APPLICATION_ERROR. This changes the service state to PAUSED which is returned when pause completes.

Reporting a RED status for a service that is not ACTIVE will have no effect but the status message provided will become the latest one exposed to the Diffusion console.

Reporting a GREEN or AMBER status will notify the framework that the handler is now (at least partly) operational. Hence, if the RED status was previously reported, the ServiceHandler.resume(com.diffusiondata.gateway.framework.ServiceHandler.ResumeReason) method will be called with a reason of APPLICATION_RECOVERED and the state will become ACTIVE when resume completes. However, the service may still remain PAUSED if it had been previously paused by user request or if there is no connection to the Diffusion server. The new service state is returned to indicate whether this is the case. If there is no other reason for the service to remain PAUSED then the state will become ACTIVE.

Reporting a GREEN or AMBER status for a service that is already ACTIVE will have no effect but the status message provided will become the latest one exposed to the Diffusion console.

If the state returned is ACTIVE then streaming services may start publishing updates again (if they were not already) and polling services will start to be polled again.

If the state returned is not ACTIVE then updates cannot be published until the service is resumed.

Parameters:

status - the status

title - the status title

description - the status description

Returns:

a CompletableFuture that completes with the new ServiceState once the service has paused or resumed based on the supplied StateHandler.Status

getState

ServiceState getState()

Returns the current state of the service.

Returns:

the service state