Java tutorial
/* 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.edgent.test.apps.iot; import static org.apache.edgent.function.Functions.discard; import java.util.Arrays; import java.util.HashSet; import java.util.Set; import org.apache.edgent.connectors.iot.IotDevice; import org.apache.edgent.function.Function; import org.apache.edgent.function.UnaryOperator; import org.apache.edgent.topology.TSink; import org.apache.edgent.topology.TStream; import org.apache.edgent.topology.Topology; import org.apache.edgent.topology.plumbing.PlumbingStreams; import com.google.gson.JsonObject; /** * A test IotDevice that echos back every event as a command with command * identifier equal to the {@code cmdId} value in the event payload. If {@code cmdId} * is not set then the event identifier is used. * */ public class EchoIotDevice implements IotDevice { public static final String EVENT_CMD_ID = "cmdId"; public static final String MY_DEVICE_TYPE = "echoDeviceType"; public static final String MY_FQDEVICE_ID = MY_DEVICE_TYPE + "/echoDeviceId"; public static final String EVENT_CMD_DEVICE = MY_FQDEVICE_ID; private final Topology topology; private TStream<JsonObject> echoCmds; public EchoIotDevice(Topology topology) { this.topology = topology; } @Override public Topology topology() { return topology; } @Override public TSink<JsonObject> events(TStream<JsonObject> stream, Function<JsonObject, String> eventId, UnaryOperator<JsonObject> payload, Function<JsonObject, Integer> qos) { stream = stream.map(e -> { JsonObject c = new JsonObject(); JsonObject evPayload = payload.apply(e); c.addProperty(CMD_DEVICE, EVENT_CMD_DEVICE); c.addProperty(CMD_ID, getCommandIdFromEvent(eventId.apply(e), evPayload)); c.add(CMD_PAYLOAD, evPayload); c.addProperty(CMD_FORMAT, "json"); c.addProperty(CMD_TS, System.currentTimeMillis()); return c; }); return handleEvents(stream); } private static String getCommandIdFromEvent(String eventId, JsonObject evPayload) { if (evPayload.has(EVENT_CMD_ID)) return evPayload.getAsJsonPrimitive(EVENT_CMD_ID).getAsString(); else return eventId; } @Override public TSink<JsonObject> events(TStream<JsonObject> stream, String eventId, int qos) { stream = stream.map(e -> { JsonObject c = new JsonObject(); c.addProperty(CMD_ID, getCommandIdFromEvent(eventId, e)); c.add(CMD_PAYLOAD, e); c.addProperty(CMD_FORMAT, "json"); c.addProperty(CMD_TS, System.currentTimeMillis()); return c; }); return handleEvents(stream); } private TSink<JsonObject> handleEvents(TStream<JsonObject> stream) { if (echoCmds == null) echoCmds = PlumbingStreams.isolate(stream, true); else echoCmds = PlumbingStreams.isolate(stream.union(echoCmds), true); return stream.sink(discard()); } @Override public TStream<JsonObject> commands(String... commands) { if (commands.length == 0) return echoCmds; Set<String> cmds = new HashSet<>(Arrays.asList(commands)); return echoCmds.filter(cmd -> cmds.contains(cmd.getAsJsonPrimitive(CMD_ID).getAsString())); } @Override public String getDeviceType() { return MY_DEVICE_TYPE; } @Override public String getDeviceId() { return MY_FQDEVICE_ID; } }