#1027: Add TaskProvider which provides requests to send during bootstrap

The DefaultBootstrapSessionManager delegates knowledge of requests to
send to BootstrapTaskProvider.
A SimpleBootstrapStoreTaskProvider use BootstrapConfigStore to know
which requests must be sent from BootstrapConfig.

leshan-server-cf/src/main/java/org/eclipse/leshan/server/californium/bootstrap/LeshanBootstrapServerBuilder.java

@@ -49,6 +49,7 @@
 import org.eclipse.leshan.server.bootstrap.DefaultBootstrapSessionManager;
 import org.eclipse.leshan.server.bootstrap.InMemoryBootstrapConfigStore;
 import org.eclipse.leshan.server.bootstrap.LwM2mBootstrapRequestSender;
+import org.eclipse.leshan.server.bootstrap.BootstrapConfigStoreTaskProvider;
 import org.eclipse.leshan.server.model.LwM2mBootstrapModelProvider;
 import org.eclipse.leshan.server.model.StandardBootstrapModelProvider;
 import org.eclipse.leshan.server.security.BootstrapSecurityStore;
@@ -410,8 +411,8 @@ public BootstrapHandler create(LwM2mBootstrapRequestSender sender,
         if (modelProvider == null)
             modelProvider = new StandardBootstrapModelProvider();
         if (sessionManager == null)
-            sessionManager = new DefaultBootstrapSessionManager(securityStore, new SecurityChecker(), configStore,
-                    modelProvider);
+            sessionManager = new DefaultBootstrapSessionManager(securityStore, new SecurityChecker(),
+                    new BootstrapConfigStoreTaskProvider(configStore), modelProvider);
         if (coapConfig == null) {
             coapConfig = createDefaultNetworkConfig();
         }

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/BootstrapConfigStoreTaskProvider.java

@@ -0,0 +1,56 @@
+/*******************************************************************************
+ * Copyright (c) 2021 Sierra Wireless and others.
+ * 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ * 
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v20.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.bootstrap;
+
+import java.util.HashMap;
+import java.util.List;
+
+import org.eclipse.leshan.core.response.LwM2mResponse;
+
+/**
+ * An implementation of {@link BootstrapTaskProvider} which use a {@link BootstrapConfigStore} to know which requests to
+ * send during a {@link BootstrapSession}.
+ */
+public class BootstrapConfigStoreTaskProvider implements BootstrapTaskProvider {
+
+    private BootstrapConfigStore store;
+
+    public BootstrapConfigStoreTaskProvider(BootstrapConfigStore store) {
+        this.store = store;
+    }
+
+    @Override
+    public Tasks getTasks(BootstrapSession session, List<LwM2mResponse> previousResponse) {
+
+        BootstrapConfig config = store.get(session.getEndpoint(), session.getIdentity(), session);
+        if (config == null)
+            return null;
+
+        Tasks tasks = new Tasks();
+        // create requests from config
+        tasks.requestsToSend = BootstrapUtil.toRequests(config, session.getContentFormat());
+
+        // We add model for Security(0), Server(0) and ACL(2) which are the only one supported by BootstrapConfig
+        // We use default 1.0 model as currently BootstrapConfig support only this model version (which should be
+        // compatible with models of LWM2M v1.1 but without new resources)
+        tasks.supportedObjects = new HashMap<>();
+        tasks.supportedObjects.put(0, "1.0");
+        tasks.supportedObjects.put(1, "1.0");
+        tasks.supportedObjects.put(2, "1.0");
+
+        return tasks;
+    }
+}

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/BootstrapSessionManager.java

@@ -124,11 +124,11 @@ public String toString() {
      * 
      * @param bsSession the bootstrap session concerned.
      * @param request The request for which we get a successful response.
-     * 
+     * @param response The response received.
      * @return a {@link BootstrapPolicy} given the way to continue the bootstrap session.
      */
     public BootstrapPolicy onResponseSuccess(BootstrapSession bsSession,
-            BootstrapDownlinkRequest<? extends LwM2mResponse> request);
+            BootstrapDownlinkRequest<? extends LwM2mResponse> request, LwM2mResponse response);
 
     /**
      * Called when we receive a error response to a request.

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/BootstrapTaskProvider.java

@@ -0,0 +1,72 @@
+/*******************************************************************************
+ * Copyright (c) 2021 Sierra Wireless and others.
+ * 
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ * 
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v20.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.bootstrap;
+
+import java.util.List;
+import java.util.Map;
+
+import org.eclipse.leshan.core.model.LwM2mModel;
+import org.eclipse.leshan.core.request.BootstrapDiscoverRequest;
+import org.eclipse.leshan.core.request.BootstrapDownlinkRequest;
+import org.eclipse.leshan.core.request.BootstrapWriteRequest;
+import org.eclipse.leshan.core.response.LwM2mResponse;
+
+/**
+ * A class responsible to return tasks to do during a {@link BootstrapSession}
+ * <p>
+ * This class is used by {@link DefaultBootstrapSessionManager}.
+ * <p>
+ * {@link #getTasks(BootstrapSession, List)} must return requests to send to the client. During 1 session,
+ * {@link #getTasks(BootstrapSession, List)} can be called several time. Responses received for first batch of requests
+ * can be used to determine next request to send. E.g. first batch of Requests could be a
+ * {@link BootstrapDiscoverRequest} or a BootstrapReadRequest and response can be used to determine which
+ * {@link BootstrapWriteRequest} to Send.
+ * 
+ * @see BootstrapConfigStoreTaskProvider
+ */
+public interface BootstrapTaskProvider {
+
+    /**
+     * a batch of requests to send.
+     *
+     */
+    public class Tasks {
+        /**
+         * the list of request to send
+         */
+        public List<BootstrapDownlinkRequest<? extends LwM2mResponse>> requestsToSend;
+
+        /**
+         * Object (with version) supported by the client. {@link LwM2mModel} needed to encode/decode payload of request
+         * will be created from this data
+         */
+        public Map<Integer, String> supportedObjects;
+
+        /**
+         * if true {@link BootstrapTaskProvider#getTasks(BootstrapSession, List)} will not be called again for this
+         * session
+         */
+        public boolean last = true;
+    }
+
+    /**
+     * @param previousResponses a list of {@link LwM2mResponse} received from previous executed {@link Tasks}. It can be
+     *        <code>null</code> if this is the first call for this session.
+     * @return next tasks to do (next requests to send), returning <code>null</code> means there is nothing to do with
+     *         this client.
+     */
+    Tasks getTasks(BootstrapSession session, List<LwM2mResponse> previousResponses);
+}

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/DefaultBootstrapHandler.java

@@ -141,7 +141,7 @@ protected void sendRequest(final BootstrapSession session,
             public void safeOnResponse(LwM2mResponse response) {
                 if (response.isSuccess()) {
                     LOG.trace("{} receives {} for {}", session, response, requestToSend);
-                    BootstrapPolicy policy = sessionManager.onResponseSuccess(session, requestToSend);
+                    BootstrapPolicy policy = sessionManager.onResponseSuccess(session, requestToSend, response);
                     afterRequest(session, policy, requestToSend);
                 } else {
                     LOG.debug("{} receives {} for {}", session, response, requestToSend);

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/DefaultBootstrapSession.java

@@ -38,9 +38,11 @@ public class DefaultBootstrapSession implements BootstrapSession {
     private final ContentFormat contentFormat;
     private final long creationTime;
     private final BootstrapRequest request;
-    private LwM2mModel model;
-    private List<BootstrapDownlinkRequest<? extends LwM2mResponse>> requests;
 
+    private volatile LwM2mModel model;
+    private volatile List<BootstrapDownlinkRequest<? extends LwM2mResponse>> requests;
+    private volatile List<LwM2mResponse> responses;
+    private volatile boolean moreTasks = false;
     private volatile boolean cancelled = false;
 
     /**
@@ -147,6 +149,14 @@ public void setRequests(List<BootstrapDownlinkRequest<? extends LwM2mResponse>>
         this.requests = requests;
     }
 
+    public List<LwM2mResponse> getResponses() {
+        return responses;
+    }
+
+    public void setResponses(List<LwM2mResponse> responses) {
+        this.responses = responses;
+    }
+
     @Override
     public LwM2mModel getModel() {
         return model;
@@ -156,6 +166,14 @@ public void setModel(LwM2mModel model) {
         this.model = model;
     }
 
+    public void setMoreTasks(boolean moreTasks) {
+        this.moreTasks = moreTasks;
+    }
+
+    public boolean hasMoreTasks() {
+        return moreTasks;
+    }
+
     @Override
     public void cancel() {
         cancelled = true;

leshan-server-core/src/main/java/org/eclipse/leshan/server/bootstrap/DefaultBootstrapSessionManager.java

@@ -15,7 +15,7 @@
  *******************************************************************************/
 package org.eclipse.leshan.server.bootstrap;
 
-import java.util.HashMap;
+import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
@@ -25,6 +25,7 @@
 import org.eclipse.leshan.core.request.Identity;
 import org.eclipse.leshan.core.response.LwM2mResponse;
 import org.eclipse.leshan.core.util.Validate;
+import org.eclipse.leshan.server.bootstrap.BootstrapTaskProvider.Tasks;
 import org.eclipse.leshan.server.model.LwM2mBootstrapModelProvider;
 import org.eclipse.leshan.server.model.StandardBootstrapModelProvider;
 import org.eclipse.leshan.server.security.BootstrapSecurityStore;
@@ -46,7 +47,7 @@ public class DefaultBootstrapSessionManager implements BootstrapSessionManager {
 
     private BootstrapSecurityStore bsSecurityStore;
     private SecurityChecker securityChecker;
-    private BootstrapConfigStore configStore;
+    private BootstrapTaskProvider tasksProvider;
     private LwM2mBootstrapModelProvider modelProvider;
 
     /**
@@ -56,7 +57,8 @@ public class DefaultBootstrapSessionManager implements BootstrapSessionManager {
      * @param bsSecurityStore the {@link BootstrapSecurityStore} used by default {@link SecurityChecker}.
      */
     public DefaultBootstrapSessionManager(BootstrapSecurityStore bsSecurityStore, BootstrapConfigStore configStore) {
-        this(bsSecurityStore, new SecurityChecker(), configStore, new StandardBootstrapModelProvider());
+        this(bsSecurityStore, new SecurityChecker(), new BootstrapConfigStoreTaskProvider(configStore),
+                new StandardBootstrapModelProvider());
     }
 
     /**
@@ -66,11 +68,11 @@ public DefaultBootstrapSessionManager(BootstrapSecurityStore bsSecurityStore, Bo
      * @param securityChecker used to accept or refuse new {@link BootstrapSession}.
      */
     public DefaultBootstrapSessionManager(BootstrapSecurityStore bsSecurityStore, SecurityChecker securityChecker,
-            BootstrapConfigStore configStore, LwM2mBootstrapModelProvider modelProvider) {
-        Validate.notNull(configStore);
+            BootstrapTaskProvider tasksProvider, LwM2mBootstrapModelProvider modelProvider) {
+        Validate.notNull(tasksProvider);
         this.bsSecurityStore = bsSecurityStore;
         this.securityChecker = securityChecker;
-        this.configStore = configStore;
+        this.tasksProvider = tasksProvider;
         this.modelProvider = modelProvider;
     }
 
@@ -90,27 +92,28 @@ public BootstrapSession begin(BootstrapRequest request, Identity clientIdentity)
 
     @Override
     public boolean hasConfigFor(BootstrapSession session) {
-        BootstrapConfig configuration = configStore.get(session.getEndpoint(), session.getIdentity(), session);
-        if (configuration == null)
+        Tasks firstTasks = tasksProvider.getTasks(session, null);
+        if (firstTasks == null)
             return false;
 
-        initSessionFromConfig(session, configuration);
+        initTasks(session, firstTasks);
         return true;
     }
 
-    protected void initSessionFromConfig(BootstrapSession bssession, BootstrapConfig configuration) {
+    protected void initTasks(BootstrapSession bssession, Tasks tasks) {
         DefaultBootstrapSession session = (DefaultBootstrapSession) bssession;
         // set models
-        HashMap<Integer, String> supportedObjects = new HashMap<>();
-        supportedObjects.put(0, "1.0");
-        supportedObjects.put(1, "1.0");
-        supportedObjects.put(2, "1.0");
-        session.setModel(modelProvider.getObjectModel(session, supportedObjects));
+        if (tasks.supportedObjects != null)
+            session.setModel(modelProvider.getObjectModel(session, tasks.supportedObjects));
 
         // set Requests to Send
-        List<BootstrapDownlinkRequest<? extends LwM2mResponse>> requests = BootstrapUtil.toRequests(configuration,
-                session.getContentFormat());
-        session.setRequests(requests);
+        session.setRequests(tasks.requestsToSend);
+
+        // prepare list where we will store Responses
+        session.setResponses(new ArrayList<LwM2mResponse>(tasks.requestsToSend.size()));
+
+        // is last Tasks ?
+        session.setMoreTasks(!tasks.last);
     }
 
     @Override
@@ -121,21 +124,37 @@ public BootstrapDownlinkRequest<? extends LwM2mResponse> getFirstRequest(Bootstr
     protected BootstrapDownlinkRequest<? extends LwM2mResponse> nextRequest(BootstrapSession bsSession) {
         DefaultBootstrapSession session = (DefaultBootstrapSession) bsSession;
         List<BootstrapDownlinkRequest<? extends LwM2mResponse>> requestsToSend = session.getRequests();
-        if (requestsToSend.isEmpty()) {
-            return new BootstrapFinishRequest();
-        } else {
+
+        if (!requestsToSend.isEmpty()) {
+            // get next requests
             return requestsToSend.remove(0);
+        } else {
+            if (session.hasMoreTasks()) {
+                Tasks nextTasks = tasksProvider.getTasks(session, session.getResponses());
+                if (nextTasks == null) {
+                    session.setMoreTasks(false);
+                    return new BootstrapFinishRequest();
+                }
+
+                initTasks(session, nextTasks);
+                return nextRequest(bsSession);
+            } else {
+                return new BootstrapFinishRequest();
+            }
         }
     }
 
     @Override
     public BootstrapPolicy onResponseSuccess(BootstrapSession bsSession,
-            BootstrapDownlinkRequest<? extends LwM2mResponse> request) {
+            BootstrapDownlinkRequest<? extends LwM2mResponse> request, LwM2mResponse response) {
         if (LOG.isTraceEnabled())
             LOG.trace("{} {} receives success response for {} : {}", request.getClass().getSimpleName(),
                     request.getPath(), bsSession, request);
 
         if (!(request instanceof BootstrapFinishRequest)) {
+            // store response
+            DefaultBootstrapSession session = (DefaultBootstrapSession) bsSession;
+            session.getResponses().add(response);
             // on success for NOT bootstrap finish request we send next request
             return BootstrapPolicy.continueWith(nextRequest(bsSession));
         } else {
@@ -152,6 +171,10 @@ public BootstrapPolicy onResponseError(BootstrapSession bsSession,
                     request.getPath(), response, bsSession, request);
 
         if (!(request instanceof BootstrapFinishRequest)) {
+            // store response
+            DefaultBootstrapSession session = (DefaultBootstrapSession) bsSession;
+            session.getResponses().add(response);
+
             // on response error for NOT bootstrap finish request we continue any sending next request
             return BootstrapPolicy.continueWith(nextRequest(bsSession));
         } else {