com.hotels.styx.api.HttpInterceptor Maven / Gradle / Ivy
/*
Copyright (C) 2013-2018 Expedia Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package com.hotels.styx.api;
import java.util.Optional;
import rx.Observable;
/**
* An interceptor can interact with a request before it is passed to the handler and/or the response from the handler
* before it is returned.
*
* The interceptor can simply log/record data, or it could modify the request/response.
*/
public interface HttpInterceptor {
/**
* Context. Provides application-wide data to the interceptor.
*/
interface Context {
/**
* Add key-value pair to the context.
*
* @param key key
* @param value value
*/
void add(String key, Object value);
/**
* Retrieve a value from the context, converted to a given class.
*
* @param key key
* @param clazz class of value
* @param class of value
* @return value
* @deprecated use getIfAvailable instead
*/
@Deprecated
T get(String key, Class clazz);
default Optional getIfAvailable(String key, Class clazz) {
return Optional.ofNullable(get(key, clazz));
}
Context EMPTY = new Context() {
@Override
public void add(String key, Object value) {
}
@Override
public T get(String key, Class clazz) {
return null;
}
};
}
/**
* Coordinates the propagation of request and response through a chain of interceptors and back.
*/
interface Chain {
/**
* Returns the {@link Context}. Default implementation returns null.
*
* @return the context
*/
default Context context() {
return null;
}
/**
* Propagate to the next interceptor, or to the handler if there are no more interceptors.
*
* @param request request to propagate
* @return observable that will provide the response
*/
Observable proceed(HttpRequest request);
}
/**
* Executes the interceptor's action. The interceptor is responsible for continuing execution of the interceptor
* stack with the {@link com.hotels.styx.api.HttpInterceptor.Chain}.
*
* @param request HTTP request
* @param chain chain
* @return observable that will provide the response
*/
Observable intercept(HttpRequest request, Chain chain);
}