JsonListHandler.java

// Copyright 2011 Google 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.google.appengine.tools.pipeline.impl.servlets;

import com.google.appengine.tools.pipeline.impl.PipelineManager;
import com.google.appengine.tools.pipeline.impl.model.JobRecord;
import com.google.appengine.tools.pipeline.util.Pair;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * @author tkaitchuck@google.com (Tom Kaitchuck)
 */
public class JsonListHandler {

  public static final String PATH_COMPONENT = "rpc/list";
  private static final String CLASS_FILTER_PARAMETER = "class_path";
  private static final String CURSOR_PARAMETER = "cursor";
  private static final String LIMIT_PARAMETER = "limit";

  public static void doGet(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException {
    String classFilter = getParam(req, CLASS_FILTER_PARAMETER);
    String cursor = getParam(req, CURSOR_PARAMETER);
    String limit = getParam(req, LIMIT_PARAMETER);
    Pair<? extends Iterable<JobRecord>, String> pipelineRoots = PipelineManager.queryRootPipelines(
        classFilter, cursor, limit == null ? 100 : Integer.parseInt(limit));
    String asJson = JsonGenerator.pipelineRootsToJson(pipelineRoots);
    try {
      resp.getWriter().write(asJson);
    } catch (IOException e) {
      throw new ServletException(e);
    }
  }

  private static String getParam(HttpServletRequest req, String name) {
    String value = req.getParameter(name);
    if (value != null) {
      value = value.trim();
      if (value.isEmpty()) {
        value = null;
      }
    }
    return value;
  }
}