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/**
 * 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 com.datatorrent.lib.appdata.schemas;

import javax.validation.constraints.NotNull;

import com.google.common.base.Preconditions;

/**
 * This is the base class used to represent AppData queries. App Data quries have the following features:
 * 
*
*
    *
  • id:This is the client id for the query. It is also the same id which is attached to results.
  • *
  • countdown:This is the number of times results are returned for the query. This is meant to allow * the client to display updated data without incurring the latency of issuing a separate query for each update.
  • *
  • schemaKeys:This is used in the case where an operator responding to queries is hosting multiple schemas. When * an operator is exposing multiple schemas, the schemakeys are used to select the schema that this query is intended to be * run against.
  • *
* * This base class holds the basic setters and getters for manipulating and storing these query properies. * @since 3.0.0 */ public abstract class QRBase extends Message { /** * The String that is used as a key in JSON requests to represent the countdown. */ public static final String FIELD_COUNTDOWN = "countdown"; /** * The String that is used as a key in JSON requests to represent the query id. */ public static final String FIELD_ID = "id"; /** * The query id. */ @NotNull private String id; /** * The query countdown. */ private long countdown; /** * Creates a query base object with nothing set. */ public QRBase() { } /** * Creates a query with the given id. * @param id The query id. */ public QRBase(String id) { this.id = Preconditions.checkNotNull(id); } /** * Creates a query with the given id and type. * @param id The query id. * @param type The type of the query. */ public QRBase(String id, String type) { super(type); this.id = Preconditions.checkNotNull(id); } /** * Creates a query with the given id, type, and countdown. * @param id The query id. * @param type The type of the query. * @param countdown The countdown for the query. */ public QRBase(String id, String type, long countdown) { this(id, type); setCountdown(countdown); } /** * Sets the countdown for the query. Valid countdowns are greater than zero. * @param countdown The countdown for the query. */ public final void setCountdown(long countdown) { Preconditions.checkArgument(countdown > 0L); this.countdown = countdown; } /** * Gets the countdown for the query. * @return The countdown for the query. */ public long getCountdown() { return countdown; } /** * Returns true if the countdown is one. False otherwise. * @return True if the countdown is one. False otherwise. */ public boolean isOneTime() { return countdown == 0L; } /** * Returns the query id. * @return The query id. */ public String getId() { return id; } /** * Sets the query id. * @param id The query id to set. */ public void setId(String id) { this.id = id; } @Override public String toString() { return "Query{" + "id=" + id + ", type=" + getType() + '}'; } }




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