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Last active January 31, 2020 12:14
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RedirectResolver proposal
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.sling.TBD;
import org.osgi.annotation.versioning.ProviderType;
import javax.servlet.http.HttpServletRequest;
/**
* A RedirectResolver resolves a redirect in the context of a request. It resolves that redirect having first been bound
* to a Resource. This is typically achieved through the Adapt to mechanism eg resource.adaptTo(RedirectResolver.class).
*
* Implementations should implement an AdapterFactory to perform the adaption to an implementation of this class. That class
* should implement the resolve method such that the methods of the Redirect Response are called to define the RedirectResponse.
*
* The implementation of the resolve method indicates that it has successfully resolved a redirect by setting a setting a status code
* see the documentation of the RedirectResponse class for more information.
*/
@ProviderType
public interface RedirectResolver {
/**
* Resolve the redirect for the resource bound to this redirect resolver, in the context of the request.
* May decline to perform this operation, but not setting the status code on the redirectResponse.
* @param request the context of the resolution given by a request. This is required and must not be null. It will indicate
* where the request came from, including the exposed edge Host and other http request headers. Typcally
* and implementation will use these to determine aspects of the redirect response. For instance, requests through
* a CDN may redirect differently from request made direct from a service running behind the CDN.
* @param redirectResponse the redirect response class. This is implemented by the caller and will contain the methods
* defined in the base class at the time the implementation of the RedirectResolver was written.
* If methods are added to the RedirectResponse class, they will be added in a way to ensure existing
* implementations do not need to be updated to continue to work.
*/
void resolve(HttpServletRequest request, RedirectResponse redirectResponse);
}
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.sling.TBD;
/**
* A Redirect response defines the base class used to hold information to build a redirect. It is extended
* by the caller to RedirectResolver.resolve, and called by the implementation of the RedirectResolver interface.
* On return from that call the caller will use the information in the RedirectResponse to perform whatever operation
* it needs to perform. Typically this will be returning a http redirect, but there may be other uses.
*
* A class is being used rather than an interface to allow empty setter methods to be added over time.
* Callers to RedirectResolver.resolve should override those methods that they need information for. New methods to this
* class should be added with empty implementations to ensure that pre-exiting classes extending this method to not
* have to be updated.
*/
public class RedirectResponse {
/**
* Value to be used in setSetatus to indicate no redirect available for context of the resolution.
*/
public static final int NO_REDIRECT = -1;
/**
* Set a header on the response. This will replace existing headers of the same name.
* If called twice, the header will be reset with the latest value.
* Multiple headers of the same name are not supported.
* @param name the name of the header.
* @param value the value of the header.
*/
public void setHeader(String name, String value) {
}
/**
* Set the redirect to be used. Will not be sent until the RedirectResponse is returned from the
* RedirectResolver.resolver and processed.
* @param url the url to set, should be set in the context of a request.
*/
public void setRedirect(String url) {
}
/**
* Set the status code used in the redirect response. Typically 301, but other status codes may be used.
* If the status code is not set, or is set to -1 then the redirect will not be acted on.
* @param i status code number.
*/
public void setStatus(int i) {
}
}
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ieb commented Jan 31, 2020

Carsten advised against that pattern, will discuss on list.

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