Package io.servicetalk.http.netty

Class HttpLifecycleObserverServiceFilter

java.lang.Object

io.servicetalk.http.netty.HttpLifecycleObserverServiceFilter

All Implemented Interfaces:

HttpExecutionStrategyInfluencer, StreamingHttpServiceFilterFactory, ExecutionStrategyInfluencer<HttpExecutionStrategy>

Direct Known Subclasses:

GrpcLifecycleObserverServiceFilter

public class HttpLifecycleObserverServiceFilter
extends Object
implements StreamingHttpServiceFilterFactory

An HTTP service filter that tracks events during request/response lifecycle.

The result of the observed behavior will depend on the position of this filter in the execution chain. This filter is recommended to be appended as one of the first filters using HttpServerBuilder.appendNonOffloadingServiceFilter(StreamingHttpServiceFilterFactory) method to account for all work done by other filters and offloading of the requests processing. It can be appended at another position, considering the following:

• After a tracing filter or any other filter that populates request context, AsyncContext, MDC, or alters HttpRequestMetaData if that information has to be available for HttpLifecycleObserver.HttpExchangeObserver.
• After TimeoutHttpRequesterFilter if the timeout event should be observed as cancellation instead of an error.
• After any filter that can reject requests, like BasicAuthHttpServiceFilter, if only allowed requests should be observed.
• Before any filter that can reject requests, like BasicAuthHttpServiceFilter, if all incoming requests have to be observed.
• Before any filter that populates response context or alters HttpResponseMetaData if that information has to be available for HttpLifecycleObserver.HttpExchangeObserver.
• Before any filter that maps/translates HttpResponseMetaData into an exception or throws an exception during response payload body transformation if that exception has to be observed by HttpLifecycleObserver.HttpExchangeObserver.
• Before any exception mapping filter that maps an exception into a valid response, like HttpExceptionMapperServiceFilter, if the HttpLifecycleObserver.HttpExchangeObserver should see what status code is returned to the client.
• Using HttpServerBuilder.appendServiceFilter(StreamingHttpServiceFilterFactory) if an exchange should be observed after it's offloaded from an IoExecutor (if offloading is enabled).
• Using HttpServerBuilder.appendNonOffloadingServiceFilter(Predicate, StreamingHttpServiceFilterFactory) or HttpServerBuilder.appendServiceFilter(Predicate, StreamingHttpServiceFilterFactory) if the observer should be applied conditionally.
• As the last HttpServerBuilder.appendServiceFilter(StreamingHttpServiceFilterFactory) if only service business logic should be observed without accounting for work of any other filters.

An alternative way to install an HttpLifecycleObserver is to use HttpServerBuilder.lifecycleObserver(HttpLifecycleObserver).

See Also:

• HttpServerBuilder.lifecycleObserver(HttpLifecycleObserver)

Constructor Summary

Constructors

Constructor	Description
HttpLifecycleObserverServiceFilter(HttpLifecycleObserver observer)	Create a new instance.

Method Summary

Modifier and Type	Method	Description
final StreamingHttpServiceFilter	create(StreamingHttpService service)	Create a StreamingHttpServiceFilter using the provided StreamingHttpService.
List<? extends HttpLifecycleObserver>	lifecycleObservers()	Returns the HttpLifecycleObservers used by this filter.
final HttpExecutionStrategy	requiredOffloads()	Return an ExecutionStrategy that describes the offloads required by the influencer.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.servicetalk.http.api.HttpExecutionStrategyInfluencer

influenceStrategy, requiredOffloads

Constructor Details

HttpLifecycleObserverServiceFilter

public HttpLifecycleObserverServiceFilter(HttpLifecycleObserver observer)

Create a new instance.

Parameters:

observer - The observer implementation that consumes HTTP lifecycle events.

Method Details

create

public final StreamingHttpServiceFilter create(StreamingHttpService service)

Description copied from interface: StreamingHttpServiceFilterFactory

Create a StreamingHttpServiceFilter using the provided StreamingHttpService.

Specified by:

create in interface StreamingHttpServiceFilterFactory

Parameters:

service - StreamingHttpService to filter

Returns:

StreamingHttpServiceFilter using the provided StreamingHttpService.

lifecycleObservers

public List<? extends HttpLifecycleObserver> lifecycleObservers()

Returns the HttpLifecycleObservers used by this filter.

Returns:

a List of HttpLifecycleObservers used by this filter

requiredOffloads

public final HttpExecutionStrategy requiredOffloads()

Description copied from interface: HttpExecutionStrategyInfluencer

Return an ExecutionStrategy that describes the offloads required by the influencer.

The provided default implementation requests offloading of all operations. Implementations that require no offloading should be careful to return HttpExecutionStrategies.offloadNone() rather than HttpExecutionStrategies.offloadNever(). Implementations should avoid returning HttpExecutionStrategies.defaultStrategy(), instead returning the strategy they require or HttpExecutionStrategies.offloadAll() if offloading for all paths is required (safe default).

Specified by:

requiredOffloads in interface ExecutionStrategyInfluencer<HttpExecutionStrategy>

Specified by:

requiredOffloads in interface HttpExecutionStrategyInfluencer

Returns:

the ExecutionStrategy required by the influencer.