com.pingidentity.pa.sdk.ha.lb

Interface LoadBalancingHandler

All Known Implementing Classes:

LoadBalancingStrategy.NONE

public interface LoadBalancingHandler

A LoadBalancingHandler is the runtime component of a LoadBalancingStrategy that provides the logic for load balancing requests to TargetHosts configured for a Site.

LoadBalancingHandler implementations must be thread-safe; that is, multiple threads may be running through a single instance of the implementation at any one time.

A LoadBalancingHandler instance is scoped to the Site to which the LoadBalancingStrategy is assigned, and a single instance is created for each assignment of a LoadBalancingStrategy to a Site, by the EntityScopedHandlerPlugin.getHandler() method. This constraint also implies that a single LoadBalancingHandler instance will only ever see TargetHosts for a single Site.

Any server-side state for a LoadBalancingStrategy should be stored as members of the LoadBalancingHandler implementation because a LoadBalancingHandler instance may persist across changes in the associated LoadBalancingStrategy configuration. This behavior is controlled by the EntityScopedHandlerPlugin.getHandler(Object) method. This functionality facilitates the storage of server-side state that persists across changes in the configuration such as the addition of new TargetHosts to a Site or changes to the LoadBalancingStrategy configuration.

A LoadBalancingHandler is guaranteed to process an exchange after both Rules and SiteAuthenticators have processed the exchange.

Method Summary

Modifier and Type	Method and Description
TargetHost	calculateTargetHost(Exchange exchange, List<TargetHost> availableHosts, List<TargetHost> configuredHosts) Calculate the target host, given the list of available hosts and the current exchange.
void	handleResponse(Exchange exchange, TargetHost targetHost) Updates any internal data based on the response and optionally updates the response.

Method Detail

calculateTargetHost

TargetHost calculateTargetHost(Exchange exchange,
                               List<TargetHost> availableHosts,
                               List<TargetHost> configuredHosts)

Calculate the target host, given the list of available hosts and the current exchange. This method may be invoked more than once per exchange if the selected TargetHost is detected as unavailable after it is selected. To store data in between invocations, use the Exchange.setProperty(ExchangeProperty, Object) method.

Parameters:

exchange - The exchange.

availableHosts - The list of available hosts for a Site. This list cannot be modified by implementations.

configuredHosts - The list of configured hosts for a Site. This can be used to determine which hosts for the Site are available and perform any necessary cleanup for this case. This list cannot be modified by implementations.

Returns:

the target host or null if none could be determined. The behavior is undefined when the TargetHost returned is not an element of the availableHosts list.

handleResponse

void handleResponse(Exchange exchange,
                    TargetHost targetHost)

Updates any internal data based on the response and optionally updates the response. This method will be invoked once per exchange.

Parameters:

exchange - The exchange containing the response.

targetHost - The target host used for the request.