src/adaptorlib/Response.java

// Copyright 2011 Google Inc. All Rights Reserved.
//
// 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 adaptorlib;

import java.io.*;
import java.net.URI;
import java.util.Map;

/**
 * Interface provided to {@link Adaptor#getDocContent} for performing the
 * actions needed to satisfy a request.
 *
 * <p>There are several ways that a request can be processed. In the simplest
 * case an Adaptor always sets different pieces of metadata, calls {@link
 * #getOutputStream}, and writes the document contents. If the document does not
 * exist, it should call {@link #respondNotFound} instead.
 *
 * <p>For improved efficiency during recrawl by the GSA, an Adaptor should check
 * {@link Request#hasChangedSinceLastAccess} and call {@link
 * #respondNotModified} when it is {@code true}. This prevents the Adaptor from
 * ever needing to retrieve the document contents and metadata.
 */
public interface Response {
  /**
   * Respond to the GSA or other client that it already has the latest version
   * of a file and its metadata. If you have called other methods on this object
   * to provide various metadata, the effects of those methods will be ignored.
   *
   * <p>If called, this must be the last call to this interface. Once you call
   * this method, for the rest of the processing, exceptions may no longer be
   * communicated to clients cleanly.
   */
  public void respondNotModified() throws IOException;

  /**
   * Respond to the GSA or other client that the request document does not
   * exist. If you have called other methods on this object, the effects of
   * those methods will be ignored.
   *
   * <p>If called, this must be the last call to this interface. Once you call
   * this method, for the rest of the processing, exceptions may no longer be
   * communicated to the clients cleanly.
   */
  public void respondNotFound() throws IOException;

  /**
   * Get stream to write document contents to. There is no need to flush or
   * close the {@code OutputStream} when done.
   *
   * <p>If called, this must be the last call to this interface (although, for
   * convenience, you may call this method multiple times). Once you call this
   * method, for the rest of the processing, exceptions may no longer be
   * communicated to clients cleanly.
   */
  public OutputStream getOutputStream() throws IOException;

  /**
   * Describe the content type of the document.
   */
  public void setContentType(String contentType);

  /**
   * Provide metadata that applies to the document.
   *
   * @throws IllegalArgumentException if metadata contains {@code null} or empty
   *     keys or {@code null} values
   */
  public void setMetadata(Map<String, String> metadata);

  /**
   * Provide the document's ACLs for early-binding security on the GSA.
   */
  public void setAcl(Acl acl);

  /**
   * Add a hyperlink for the GSA to follow without modifying the document
   * contents. This is equivalent to the following HTML: {@code
   * <a href='$uri'>$text</a>}. If you want to link to a {@link DocId}, then you
   * may use the {@link DocIdEncoder} provided by {@link
   * AdaptorContext#getDocIdEncoder} to produce an appropriate URI.
   *
   * @param uri the URI of the anchor
   * @param text the text of the anchor, or {@code null}
   * @throws NullPointerException if {@code uri} is {@code null}
   */
  public void addAnchor(URI uri, String text);
}