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A LWM2M client and server based on Californium (CoAP) all in one.
There is a newer version: 1.0.0-M11
/*******************************************************************************
 * Copyright (c) 2017 Sierra Wireless and others.
 * 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 * 
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *    http://www.eclipse.org/org/documents/edl-v10.html.
 * 
 * Contributors:
 *     Sierra Wireless - initial API and implementation
 *******************************************************************************/
package org.eclipse.leshan.server.californium;

import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.eclipse.californium.core.coap.Request;
import org.eclipse.leshan.core.node.LwM2mPath;
import org.eclipse.leshan.core.observation.Observation;
import org.eclipse.leshan.core.request.ObserveRequest;

/**
 * Utility functions to help to handle observation in Leshan. Those helper functions are only needed if you're
 * implementing your own {@link CaliforniumRegistrationStore}.
 */
public class ObserveUtil {

    /* keys used to populate the request context */
    public static final String CTX_ENDPOINT = "leshan-endpoint";
    public static final String CTX_REGID = "leshan-regId";
    public static final String CTX_LWM2M_PATH = "leshan-path";

    /**
     * Create a LWM2M observation from a CoAP request.
     */
    public static Observation createLwM2mObservation(Request request) {
        String regId = null;
        String lwm2mPath = null;
        Map context = null;

        for (Entry ctx : request.getUserContext().entrySet()) {
            switch (ctx.getKey()) {
            case CTX_REGID:
                regId = ctx.getValue();
                break;
            case CTX_LWM2M_PATH:
                lwm2mPath = ctx.getValue();
                break;
            case CTX_ENDPOINT:
                break;
            default:
                if (context == null) {
                    context = new HashMap<>();
                }
                context.put(ctx.getKey(), ctx.getValue());
            }
        }
        return new Observation(request.getToken().getBytes(), regId, new LwM2mPath(lwm2mPath), context);
    }

    /**
     * Create a CoAP observe request context with specific keys needed for internal Leshan working.
     */
    public static Map createCoapObserveRequestContext(String endpoint, String registrationId,
            ObserveRequest request) {
        Map context = new HashMap<>();
        context.put(CTX_ENDPOINT, endpoint);
        context.put(CTX_REGID, registrationId);
        context.put(CTX_LWM2M_PATH, request.getPath().toString());
        for (Entry ctx : request.getContext().entrySet()) {
            context.put(ctx.getKey(), ctx.getValue());
        }
        return context;
    }

    public static String extractRegistrationId(org.eclipse.californium.core.observe.Observation observation) {
        return observation.getRequest().getUserContext().get(CTX_REGID);
    }

    public static String extractLwm2mPath(org.eclipse.californium.core.observe.Observation observation) {
        return observation.getRequest().getUserContext().get(CTX_LWM2M_PATH);
    }

    public static String extractEndpoint(org.eclipse.californium.core.observe.Observation observation) {
        return observation.getRequest().getUserContext().get(CTX_ENDPOINT);
    }

    /**
     * Validate the Californium observation. It is valid if it contains all necessary context for Leshan.
     */
    public static String validateCoapObservation(org.eclipse.californium.core.observe.Observation observation) {
        if (!observation.getRequest().getUserContext().containsKey(CTX_REGID))
            throw new IllegalStateException("missing registrationId info in the request context");
        if (!observation.getRequest().getUserContext().containsKey(CTX_LWM2M_PATH))
            throw new IllegalStateException("missing lwm2m path info in the request context");

        String endpoint = observation.getRequest().getUserContext().get(CTX_ENDPOINT);
        if (endpoint == null)
            throw new IllegalStateException("missing endpoint info in the request context");

        return endpoint;
    }
}