SONAR-4069 fix task extension point

15 files changed, 348 insertions, 285 deletions

diff --git a/plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/CorePlugin.java b/plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/CorePlugin.java
index 07f2c9fe38d..188bf6d0ee2 100644
--- a/plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/CorePlugin.java
+++ b/plugins/sonar-core-plugin/src/main/java/org/sonar/plugins/core/CorePlugin.java
@@ -117,6 +117,13 @@ import java.util.List;
 
 @Properties({
   @Property(
+      key = CoreProperties.TASK,
+      name = "Task to be executed",
+      defaultValue = CoreProperties.SCAN_TASK,
+      module = false,
+      project = false,
+      global = false),
+  @Property(
     key = CoreProperties.SERVER_BASE_URL,
     defaultValue = CoreProperties.SERVER_BASE_URL_DEFAULT_VALUE,
     name = "Server base URL",
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/TaskContainer.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/TaskContainer.java
index 7afac65e0ed..bc50ede3ea2 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/bootstrap/TaskContainer.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrap/TaskContainer.java
@@ -19,6 +19,8 @@
  */
 package org.sonar.batch.bootstrap;
 
+import org.sonar.api.CoreProperties;
+import org.sonar.api.config.Settings;
 import org.sonar.api.platform.ComponentContainer;
 import org.sonar.api.resources.ResourceTypes;
 import org.sonar.api.task.Task;
@@ -27,8 +29,6 @@ import org.sonar.api.task.TaskExtension;
 import org.sonar.api.utils.SonarException;
 import org.sonar.batch.tasks.Tasks;
 
-import javax.annotation.Nullable;
-
 public class TaskContainer extends ComponentContainer {
 
   public TaskContainer(ComponentContainer parent) {
@@ -41,23 +41,24 @@ public class TaskContainer extends ComponentContainer {
     installComponentsUsingTaskExtensions();
   }
 
-  public void executeTask(@Nullable String key) {
+  public void execute() {
     startComponents();
-    TaskDefinition taskDef = get(Tasks.class).getTaskDefinition(key);
-    if (taskDef != null) {
-      Task task = get(taskDef.getTask());
-      if (task != null) {
-        task.execute();
-      } else {
-        throw new IllegalStateException("Command " + key + " is badly defined.");
-      }
 
+    // default value is declared in CorePlugin
+    String taskKey = get(Settings.class).getString(CoreProperties.TASK);
+
+    TaskDefinition def = get(Tasks.class).definition(taskKey);
+    if (def == null) {
+      throw new SonarException("Task " + taskKey + " does not exist.");
+    }
+    Task task = get(def.taskClass());
+    if (task != null) {
+      task.execute();
     } else {
-      throw new SonarException("Command " + key + " does not exist.");
+      throw new IllegalStateException("Task " + taskKey + " is badly defined.");
     }
   }
 
-
   private void installTaskExtensions() {
     get(ExtensionInstaller.class).install(this, new ExtensionInstaller.ComponentFilter() {
       public boolean accept(Object extension) {
diff --git a/sonar-batch/src/main/java/org/sonar/batch/bootstrapper/Batch.java b/sonar-batch/src/main/java/org/sonar/batch/bootstrapper/Batch.java
index 0ea009fd64e..c4d03ea8845 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/bootstrapper/Batch.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/bootstrapper/Batch.java
@@ -27,7 +27,7 @@ import org.sonar.batch.bootstrap.BootstrapContainer;
 import org.sonar.batch.bootstrap.BootstrapProperties;
 import org.sonar.batch.bootstrap.TaskContainer;
 import org.sonar.batch.scan.ScanTask;
-import org.sonar.batch.tasks.ListTasksTask;
+import org.sonar.batch.tasks.ListTask;
 import org.sonar.core.PicoUtils;
 
 import java.util.Collections;
@@ -35,7 +35,7 @@ import java.util.List;
 import java.util.Map;
 
 /**
- * Entry point for batch bootstrappers.
+ * Entry point for sonar-runner.
  *
  * @since 2.14
  */
@@ -43,8 +43,7 @@ public final class Batch {
 
   private LoggingConfiguration logging;
   private List<Object> components;
-  private Map<String, String> globalProperties = Maps.newHashMap();
-  private String taskCommand;
+  private Map<String, String> bootstrapProperties = Maps.newHashMap();
   private ProjectReactor projectReactor;
 
   private Batch(Builder builder) {
@@ -53,16 +52,15 @@ public final class Batch {
     if (builder.environment != null) {
       components.add(builder.environment);
     }
-    if (builder.globalProperties != null) {
-      globalProperties.putAll(builder.globalProperties);
+    if (builder.bootstrapProperties != null) {
+      bootstrapProperties.putAll(builder.bootstrapProperties);
     } else {
       // For backward compatibility, previously all properties were set in root project
-      globalProperties.putAll(Maps.fromProperties(builder.projectReactor.getRoot().getProperties()));
+      bootstrapProperties.putAll(Maps.fromProperties(builder.projectReactor.getRoot().getProperties()));
     }
-    this.taskCommand = builder.taskCommand;
     projectReactor = builder.projectReactor;
     if (builder.isEnableLoggingConfiguration()) {
-      logging = LoggingConfiguration.create().setProperties(globalProperties);
+      logging = LoggingConfiguration.create().setProperties(bootstrapProperties);
     }
   }
 
@@ -83,29 +81,31 @@ public final class Batch {
   }
 
   private void startBatch() {
-    BootstrapContainer bootstrapModule = null;
+    BootstrapContainer bootstrapContainer = null;
     try {
       List all = Lists.newArrayList(components);
-      all.add(new BootstrapProperties(globalProperties));
-      all.add(projectReactor);
+      all.add(new BootstrapProperties(bootstrapProperties));
+      if (projectReactor != null) {
+        all.add(projectReactor);
+      }
 
-      bootstrapModule = BootstrapContainer.create(all);
-      bootstrapModule.startComponents();
+      bootstrapContainer = BootstrapContainer.create(all);
+      bootstrapContainer.startComponents();
 
-      TaskContainer taskContainer = new TaskContainer(bootstrapModule);
+      TaskContainer taskContainer = new TaskContainer(bootstrapContainer);
       taskContainer.add(
         ScanTask.DEFINITION, ScanTask.class,
-        ListTasksTask.DEFINITION, ListTasksTask.class
+        ListTask.DEFINITION, ListTask.class
       );
 
-      taskContainer.executeTask(taskCommand);
+      taskContainer.execute();
 
     } catch (RuntimeException e) {
       PicoUtils.propagateStartupException(e);
     } finally {
       try {
-        if (bootstrapModule != null) {
-          bootstrapModule.stopComponents();
+        if (bootstrapContainer != null) {
+          bootstrapContainer.stopComponents();
         }
       } catch (Exception e) {
         // never throw exceptions in a finally block
@@ -119,8 +119,7 @@ public final class Batch {
   }
 
   public static final class Builder {
-    private Map<String, String> globalProperties;
-    private String taskCommand;
+    private Map<String, String> bootstrapProperties;
     private ProjectReactor projectReactor;
     private EnvironmentInformation environment;
     private List<Object> components = Lists.newArrayList();
@@ -145,12 +144,7 @@ public final class Batch {
     }
 
     public Builder setGlobalProperties(Map<String, String> globalProperties) {
-      this.globalProperties = globalProperties;
-      return this;
-    }
-
-    public Builder setTaskCommand(String taskCommand) {
-      this.taskCommand = taskCommand;
+      this.bootstrapProperties = globalProperties;
       return this;
     }
 
diff --git a/sonar-batch/src/main/java/org/sonar/batch/scan/ScanTask.java b/sonar-batch/src/main/java/org/sonar/batch/scan/ScanTask.java
index 8ce1266e456..49e25856afa 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/scan/ScanTask.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/scan/ScanTask.java
@@ -19,19 +19,19 @@
  */
 package org.sonar.batch.scan;
 
+import org.sonar.api.CoreProperties;
 import org.sonar.api.platform.ComponentContainer;
 import org.sonar.api.task.Task;
 import org.sonar.api.task.TaskDefinition;
 import org.sonar.batch.bootstrap.TaskContainer;
 
 public class ScanTask implements Task {
-  public static final String COMMAND = "inspect";
 
-  public static final TaskDefinition DEFINITION = TaskDefinition.create()
-      .setDescription("Scan project and upload report to server")
-      .setName("Project Scan")
-      .setCommand(COMMAND)
-      .setTask(ScanTask.class);
+  public static final TaskDefinition DEFINITION = TaskDefinition.builder()
+    .description("Scan project")
+    .key(CoreProperties.SCAN_TASK)
+    .taskClass(ScanTask.class)
+    .build();
 
   private final ComponentContainer taskContainer;
 
diff --git a/sonar-batch/src/main/java/org/sonar/batch/tasks/ListTasksTask.java b/sonar-batch/src/main/java/org/sonar/batch/tasks/ListTask.java
index dd08729b2cf..93002714b91 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/tasks/ListTasksTask.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/tasks/ListTask.java
@@ -22,28 +22,28 @@ package org.sonar.batch.tasks;
 import org.sonar.api.task.Task;
 import org.sonar.api.task.TaskDefinition;
 
-public class ListTasksTask implements Task {
+public class ListTask implements Task {
 
-  public static final String COMMAND = "list-tasks";
+  public static final String KEY = "list";
 
-  public static final TaskDefinition DEFINITION = TaskDefinition.create()
-    .setDescription("List available tasks")
-    .setName("List Tasks")
-    .setCommand(COMMAND)
-    .setTask(ListTasksTask.class);
+  public static final TaskDefinition DEFINITION = TaskDefinition.builder()
+    .key(KEY)
+    .description("List available tasks")
+    .taskClass(ListTask.class)
+    .build();
 
-  private final Tasks taskManager;
+  private final Tasks tasks;
 
-  public ListTasksTask(Tasks taskManager) {
-    this.taskManager = taskManager;
+  public ListTask(Tasks tasks) {
+    this.tasks = tasks;
   }
 
   public void execute() {
     logBlankLine();
     log("Available tasks:");
     logBlankLine();
-    for (TaskDefinition taskDef : taskManager.getTaskDefinitions()) {
-      log("  - " + taskDef.getCommand() + ": " + taskDef.getDescription());
+    for (TaskDefinition def : tasks.definitions()) {
+      log("  - " + def.key() + ": " + def.description());
     }
     logBlankLine();
   }
diff --git a/sonar-batch/src/main/java/org/sonar/batch/tasks/Tasks.java b/sonar-batch/src/main/java/org/sonar/batch/tasks/Tasks.java
index 3c7de6d9117..6a2fa892720 100644
--- a/sonar-batch/src/main/java/org/sonar/batch/tasks/Tasks.java
+++ b/sonar-batch/src/main/java/org/sonar/batch/tasks/Tasks.java
@@ -19,103 +19,56 @@
  */
 package org.sonar.batch.tasks;
 
+import com.google.common.collect.ImmutableSortedMap;
 import com.google.common.collect.Maps;
-import org.apache.commons.lang.StringUtils;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-import org.sonar.api.CoreProperties;
-import org.sonar.api.config.Settings;
 import org.sonar.api.task.Task;
 import org.sonar.api.task.TaskComponent;
 import org.sonar.api.task.TaskDefinition;
 import org.sonar.api.utils.SonarException;
-import org.sonar.batch.scan.ScanTask;
-
-import javax.annotation.Nullable;
 
+import java.util.Collection;
 import java.util.Map;
-import java.util.regex.Pattern;
+import java.util.SortedMap;
 
 public class Tasks implements TaskComponent {
 
-  private static final Logger LOG = LoggerFactory.getLogger(Tasks.class);
-  private static final String COMMAND_PATTERN = "[a-zA-Z0-9\\-\\_]+";
-
-  private final TaskDefinition[] taskDefinitions;
-  private final Settings settings;
-
-  private final Map<String, TaskDefinition> taskDefByCommand = Maps.newHashMap();
-  private final Map<Class<? extends Task>, TaskDefinition> taskDefByTask = Maps.newHashMap();
+  private final SortedMap<String, TaskDefinition> byKey;
 
-  public Tasks(Settings settings, TaskDefinition[] taskDefinitions) {
-    this.settings = settings;
-    this.taskDefinitions = taskDefinitions;
+  public Tasks(TaskDefinition[] definitions) {
+    SortedMap<String, TaskDefinition> map = Maps.newTreeMap();
+    for (TaskDefinition definition : definitions) {
+      if (map.containsKey(definition.key())) {
+        throw new SonarException("Task '" + definition.key() + "' is declared twice");
+      }
+      map.put(definition.key(), definition);
+    }
+    this.byKey = ImmutableSortedMap.copyOf(map);
   }
 
-  public TaskDefinition getTaskDefinition(@Nullable String command) {
-    String finalCommand = StringUtils.defaultIfBlank(command, settings.getString(CoreProperties.TASK));
-    finalCommand = StringUtils.defaultIfBlank(finalCommand, ScanTask.COMMAND);
-
-    if (taskDefByCommand.containsKey(finalCommand)) {
-      return taskDefByCommand.get(finalCommand);
-    }
-    throw new SonarException("No task found for command: " + finalCommand);
+  public TaskDefinition definition(String taskKey) {
+    return byKey.get(taskKey);
   }
 
-  public TaskDefinition[] getTaskDefinitions() {
-    return taskDefinitions;
+  public Collection<TaskDefinition> definitions() {
+    return byKey.values();
   }
 
   /**
    * Perform validation of task definitions
    */
   public void start() {
-    for (TaskDefinition def : taskDefinitions) {
-      validateTask(def);
-      validateName(def);
-      validateCommand(def);
-      validateDescription(def);
-    }
+    checkDuplicatedClasses();
   }
 
-  private void validateName(TaskDefinition def) {
-    if (StringUtils.isBlank(def.getName())) {
-      throw new SonarException("Task definition for task '" + def.getTask().getName() + "' doesn't define task name");
+  private void checkDuplicatedClasses() {
+    Map<Class<? extends Task>, TaskDefinition> byClass = Maps.newHashMap();
+    for (TaskDefinition def : definitions()) {
+      TaskDefinition other = byClass.get(def.taskClass());
+      if (other == null) {
+        byClass.put(def.taskClass(), def);
+      } else {
+        throw new SonarException("Task '" + def.taskClass().getName() + "' is defined twice: first by '" + other.key() + "' and then by '" + def.key() + "'");
+      }
     }
-
   }
-
-  private void validateCommand(TaskDefinition def) {
-    String command = def.getCommand();
-    if (StringUtils.isBlank(command)) {
-      throw new SonarException("Task definition '" + def.getName() + "' doesn't define task command");
-    }
-    if (!Pattern.matches(COMMAND_PATTERN, command)) {
-      throw new SonarException("Command '" + command + "' for task definition '" + def.getName() + "' is not valid and should match " + COMMAND_PATTERN);
-    }
-    if (taskDefByCommand.containsKey(command)) {
-      throw new SonarException("Task '" + def.getName() + "' uses the same command than task '" + taskDefByCommand.get(command).getName() + "'");
-    }
-    taskDefByCommand.put(command, def);
-  }
-
-  private void validateDescription(TaskDefinition def) {
-    if (StringUtils.isBlank(def.getDescription())) {
-      LOG.warn("Task definition {} doesn't define a description. Using name as description.", def.getName());
-      def.setDescription(def.getName());
-    }
-  }
-
-  private void validateTask(TaskDefinition def) {
-    Class<? extends Task> taskClass = def.getTask();
-    if (taskClass == null) {
-      throw new SonarException("Task definition '" + def.getName() + "' doesn't define the associated task class");
-    }
-    if (taskDefByTask.containsKey(taskClass)) {
-      throw new SonarException("Task '" + def.getTask().getName() + "' is defined twice: first by '" + taskDefByTask.get(taskClass).getName() + "' and then by '" + def.getName()
-          + "'");
-    }
-    taskDefByTask.put(taskClass, def);
-  }
-
 }
diff --git a/sonar-batch/src/test/java/org/sonar/batch/scan/ScanTaskTest.java b/sonar-batch/src/test/java/org/sonar/batch/scan/ScanTaskTest.java
new file mode 100644
index 00000000000..fcf4c52244a
--- /dev/null
+++ b/sonar-batch/src/test/java/org/sonar/batch/scan/ScanTaskTest.java
@@ -0,0 +1,33 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2012 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * Sonar is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * Sonar is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sonar; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
+ */
+package org.sonar.batch.scan;
+
+import org.junit.Test;
+import org.sonar.api.CoreProperties;
+
+import static org.fest.assertions.Assertions.assertThat;
+
+public class ScanTaskTest {
+  @Test
+  public void test_definition() {
+    assertThat(ScanTask.DEFINITION).isNotNull();
+    assertThat(ScanTask.DEFINITION.key()).isEqualTo(CoreProperties.SCAN_TASK);
+  }
+}
diff --git a/sonar-batch/src/test/java/org/sonar/batch/tasks/ListTasksTaskTest.java b/sonar-batch/src/test/java/org/sonar/batch/tasks/ListTaskTest.java
index d66c0c688ed..0848ffc6894 100644
--- a/sonar-batch/src/test/java/org/sonar/batch/tasks/ListTasksTaskTest.java
+++ b/sonar-batch/src/test/java/org/sonar/batch/tasks/ListTaskTest.java
@@ -20,25 +20,42 @@
 package org.sonar.batch.tasks;
 
 import org.junit.Test;
+import org.sonar.api.task.Task;
 import org.sonar.api.task.TaskDefinition;
 
+import java.util.Arrays;
+
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
-public class ListTasksTaskTest {
+public class ListTaskTest {
   @Test
   public void should_list_available_tasks() {
-    TaskDefinition def = TaskDefinition.create().setCommand("purge").setName("Purge").setDescription("Purge database");
     Tasks tasks = mock(Tasks.class);
-    when(tasks.getTaskDefinitions()).thenReturn(new TaskDefinition[]{def});
-    ListTasksTask task = spy(new ListTasksTask(tasks));
+    when(tasks.definitions()).thenReturn(Arrays.asList(
+      TaskDefinition.builder().key("foo").description("Foo").taskClass(FooTask.class).build(),
+      TaskDefinition.builder().key("purge").description("Purge database").taskClass(FakePurgeTask.class).build()
+    ));
+
+    ListTask task = spy(new ListTask(tasks));
 
     task.execute();
 
     verify(task, times(1)).log("Available tasks:");
+    verify(task, times(1)).log("  - foo: Foo");
     verify(task, times(1)).log("  - purge: Purge database");
   }
+
+  private static class FakePurgeTask implements Task {
+    public void execute() {
+    }
+  }
+
+  private static class FooTask implements Task {
+    public void execute() {
+    }
+  }
 }
diff --git a/sonar-batch/src/test/java/org/sonar/batch/tasks/TasksTest.java b/sonar-batch/src/test/java/org/sonar/batch/tasks/TasksTest.java
index 102576ec196..a2e394d9b1b 100644
--- a/sonar-batch/src/test/java/org/sonar/batch/tasks/TasksTest.java
+++ b/sonar-batch/src/test/java/org/sonar/batch/tasks/TasksTest.java
@@ -19,12 +19,9 @@
  */
 package org.sonar.batch.tasks;
 
-import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
-import org.sonar.api.CoreProperties;
-import org.sonar.api.config.Settings;
 import org.sonar.api.task.Task;
 import org.sonar.api.task.TaskDefinition;
 import org.sonar.api.utils.SonarException;
@@ -37,115 +34,43 @@ public class TasksTest {
   @Rule
   public ExpectedException thrown = ExpectedException.none();
 
-  private Settings settings;
-
-  @Before
-  public void prepare() {
-    settings = new Settings();
-  }
-
-  @Test
-  public void shouldReturnTaskDefinitions() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {ScanTask.DEFINITION, ListTasksTask.DEFINITION});
-    assertThat(tasks.getTaskDefinitions().length).isEqualTo(2);
-  }
-
-  @Test
-  public void shouldReturnInspectionTask() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {ScanTask.DEFINITION, ListTasksTask.DEFINITION});
-    tasks.start();
-    assertThat(tasks.getTaskDefinition(ScanTask.COMMAND)).isEqualTo(ScanTask.DEFINITION);
-  }
-
-  @Test
-  public void shouldReturnInspectionTaskByDefault() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {ScanTask.DEFINITION, ListTasksTask.DEFINITION});
-    tasks.start();
-    assertThat(tasks.getTaskDefinition(null)).isEqualTo(ScanTask.DEFINITION);
-  }
-
-  @Test
-  public void shouldReturnUsePropertyWhenNoCommand() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {ScanTask.DEFINITION, ListTasksTask.DEFINITION});
-    tasks.start();
-    assertThat(tasks.getTaskDefinition(ListTasksTask.COMMAND)).isEqualTo(ListTasksTask.DEFINITION);
-    assertThat(tasks.getTaskDefinition(null)).isEqualTo(ScanTask.DEFINITION);
-
-    settings.setProperty(CoreProperties.TASK, ListTasksTask.COMMAND);
-    assertThat(tasks.getTaskDefinition(null)).isEqualTo(ListTasksTask.DEFINITION);
-    assertThat(tasks.getTaskDefinition(ScanTask.COMMAND)).isEqualTo(ScanTask.DEFINITION);
-  }
-
-  @Test
-  public void shouldThrowWhenCommandNotFound() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {ScanTask.DEFINITION, ListTasksTask.DEFINITION});
-
-    thrown.expect(SonarException.class);
-    thrown.expectMessage("No task found for command: not-exists");
-
-    tasks.getTaskDefinition("not-exists");
-  }
-
-  @Test
-  public void shouldThrowWhenCommandMissing() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setName("foo").setTask(FakeTask1.class)});
-
-    thrown.expect(SonarException.class);
-    thrown.expectMessage("Task definition 'foo' doesn't define task command");
-
-    tasks.start();
-  }
-
   @Test
-  public void shouldThrowWhenCommandInvalid() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setName("foo").setTask(FakeTask1.class).setCommand("Azc-12_bbC")});
-    tasks.start();
-
-    tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setName("foo").setTask(FakeTask1.class).setCommand("with space")});
-
-    thrown.expect(SonarException.class);
-    thrown.expectMessage("Command 'with space' for task definition 'foo' is not valid and should match [a-zA-Z0-9\\-\\_]+");
-
-    tasks.start();
+  public void should_get_definitions() {
+    Tasks tasks = new Tasks(new TaskDefinition[]{ScanTask.DEFINITION, ListTask.DEFINITION});
+    assertThat(tasks.definitions()).hasSize(2);
   }
 
   @Test
-  public void shouldThrowWhenDuplicateCommand() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {
-      TaskDefinition.create().setName("foo1").setTask(FakeTask1.class).setCommand("cmd"),
-      TaskDefinition.create().setName("foo2").setTask(FakeTask2.class).setCommand("cmd")});
-
-    thrown.expect(SonarException.class);
-    thrown.expectMessage("Task 'foo2' uses the same command than task 'foo1'");
-
+  public void should_get_definition_by_key() {
+    Tasks tasks = new Tasks(new TaskDefinition[]{ScanTask.DEFINITION, ListTask.DEFINITION});
     tasks.start();
+    assertThat(tasks.definition(ListTask.DEFINITION.key())).isEqualTo(ListTask.DEFINITION);
   }
 
   @Test
-  public void shouldThrowWhenNameMissing() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setCommand("foo").setTask(FakeTask1.class)});
+  public void should_return_null_if_task_not_found() {
+    Tasks tasks = new Tasks(new TaskDefinition[]{ScanTask.DEFINITION, ListTask.DEFINITION});
 
-    thrown.expect(SonarException.class);
-    thrown.expectMessage("Task definition for task 'org.sonar.batch.tasks.TasksTest$FakeTask1' doesn't define task name");
-
-    tasks.start();
+    assertThat(tasks.definition("not-exists")).isNull();
   }
 
   @Test
-  public void shouldThrowWhenTaskMissing() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setCommand("foo").setName("bar")});
-
+  public void should_fail_on_duplicated_keys() {
     thrown.expect(SonarException.class);
-    thrown.expectMessage("Task definition 'bar' doesn't define the associated task class");
+    thrown.expectMessage("Task 'foo' is declared twice");
 
-    tasks.start();
+    new Tasks(new TaskDefinition[]{
+      TaskDefinition.builder().key("foo").taskClass(FakeTask1.class).description("foo1").build(),
+      TaskDefinition.builder().key("foo").taskClass(FakeTask2.class).description("foo2").build()
+    });
   }
 
   @Test
-  public void shouldThrowWhenDuplicateTask() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {
-      TaskDefinition.create().setName("foo1").setTask(FakeTask1.class).setCommand("cmd1"),
-      TaskDefinition.create().setName("foo2").setTask(FakeTask1.class).setCommand("cmd2")});
+  public void should_fail_on_duplicated_class() {
+    Tasks tasks = new Tasks(new TaskDefinition[]{
+      TaskDefinition.builder().key("foo1").taskClass(FakeTask1.class).description("foo1").build(),
+      TaskDefinition.builder().key("foo2").taskClass(FakeTask1.class).description("foo1").build()
+    });
 
     thrown.expect(SonarException.class);
     thrown.expectMessage("Task 'org.sonar.batch.tasks.TasksTest$FakeTask1' is defined twice: first by 'foo1' and then by 'foo2'");
@@ -153,23 +78,12 @@ public class TasksTest {
     tasks.start();
   }
 
-  @Test
-  public void shouldUseNameWhenDescriptionIsMissing() {
-    Tasks tasks = new Tasks(settings, new TaskDefinition[] {TaskDefinition.create().setName("foo").setCommand("cmd").setTask(FakeTask1.class)});
-    tasks.start();
-
-    assertThat(tasks.getTaskDefinition("cmd").getDescription()).isEqualTo("foo");
-  }
-
   private static class FakeTask1 implements Task {
-
     public void execute() {
     }
-
   }
 
   private static class FakeTask2 implements Task {
-
     public void execute() {
     }
 
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/CoreProperties.java b/sonar-plugin-api/src/main/java/org/sonar/api/CoreProperties.java
index fdacc52dfbd..6d51b51a2a8 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/CoreProperties.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/CoreProperties.java
@@ -344,8 +344,13 @@ public interface CoreProperties {
   String TASK = "sonar.task";
 
   /**
+   * @since 3.6
+   */
+  String SCAN_TASK = "scan";
+
+  /**
    * @deprecated replaced in v3.4 by properties specific to languages, for example sonar.java.coveragePlugin
-   * See http://jira.codehaus.org/browse/SONARJAVA-39 for more details.
+   *             See http://jira.codehaus.org/browse/SONARJAVA-39 for more details.
    */
   @Deprecated
   String CORE_COVERAGE_PLUGIN_PROPERTY = "sonar.core.codeCoveragePlugin";
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/task/Task.java b/sonar-plugin-api/src/main/java/org/sonar/api/task/Task.java
index 42bfdddcaac..e705c2725b6 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/task/Task.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/task/Task.java
@@ -22,7 +22,7 @@ package org.sonar.api.task;
 
 /**
  * Implement this interface to provide the behavior of a task.
- * @since 3.5
+ * @since 3.6
  */
 public interface Task extends TaskExtension {
 
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskComponent.java b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskComponent.java
index 346b8bcf351..7cf26d1b132 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskComponent.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskComponent.java
@@ -20,10 +20,9 @@
 package org.sonar.api.task;
 
 /**
- * Dependency Injection : all the classes implementing this interface are available in the task IoC container.
- * Just add a parameter to the constructor of your component.
+ * All the classes implementing this interface can be injected in public constructors of {@link TaskExtension}.
  *
- * @since 3.5
+ * @since 3.6
  */
 public interface TaskComponent {
 }
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskDefinition.java b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskDefinition.java
index 2d7d595bd78..1fba731dd49 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskDefinition.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskDefinition.java
@@ -19,64 +19,104 @@
  */
 package org.sonar.api.task;
 
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+
+import java.util.regex.Pattern;
+
 /**
- * Implement this interface to provide a new task.
- * @since 3.5
+ * Register and describe a {@link TaskExtension}.
+ *
+ * @since 3.6
  */
-public class TaskDefinition implements TaskComponent {
+public class TaskDefinition implements TaskExtension, Comparable<TaskDefinition> {
+  static final String KEY_PATTERN = "[a-zA-Z0-9\\-\\_]+";
 
-  private String name;
-  private String description;
-  private String command;
-  private Class<? extends Task> task;
-
-  private TaskDefinition() {
+  private final String key;
+  private final String description;
+  private final Class<? extends Task> taskClass;
 
+  private TaskDefinition(Builder builder) {
+    this.key = builder.key;
+    this.description = builder.description;
+    this.taskClass = builder.taskClass;
   }
 
-  public static TaskDefinition create() {
-    return new TaskDefinition();
+  public String description() {
+    return description;
   }
 
-  public String getName() {
-    return name;
+  public String key() {
+    return key;
   }
 
-  public TaskDefinition setName(String name) {
-    this.name = name;
-    return this;
+  public Class<? extends Task> taskClass() {
+    return taskClass;
   }
 
-  public String getDescription() {
-    return description;
+  @Override
+  public String toString() {
+    return "Task " + key + "[class=" + taskClass.getName() + ", desc=" + description + "]";
   }
 
-  public TaskDefinition setDescription(String description) {
-    this.description = description;
-    return this;
+  public static Builder builder() {
+    return new Builder();
   }
 
-  public String getCommand() {
-    return command;
-  }
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
 
-  public TaskDefinition setCommand(String command) {
-    this.command = command;
-    return this;
+    TaskDefinition that = (TaskDefinition) o;
+    if (!key.equals(that.key)) {
+      return false;
+    }
+    return true;
   }
 
-  public Class<? extends Task> getTask() {
-    return task;
+  @Override
+  public int hashCode() {
+    return key.hashCode();
   }
 
-  public TaskDefinition setTask(Class<? extends Task> task) {
-    this.task = task;
-    return this;
+  public int compareTo(TaskDefinition o) {
+    return key.compareTo(o.key);
   }
 
-  @Override
-  public String toString() {
-    return "Definition of task " + task + " with command " + command;
-  }
+  public static class Builder {
+    private String key;
+    private String description;
+    private Class<? extends Task> taskClass;
+
+    private Builder() {
+    }
 
+    public Builder key(String key) {
+      this.key = key;
+      return this;
+    }
+
+    public Builder description(String s) {
+      this.description = s;
+      return this;
+    }
+
+    public Builder taskClass(Class<? extends Task> taskClass) {
+      this.taskClass = taskClass;
+      return this;
+    }
+
+    public TaskDefinition build() {
+      Preconditions.checkArgument(!Strings.isNullOrEmpty(key), "Task key must be set");
+      Preconditions.checkArgument(Pattern.matches(KEY_PATTERN, key), "Task key '" + key + "' must match " + KEY_PATTERN);
+      Preconditions.checkArgument(!Strings.isNullOrEmpty(description), "Description must be set for task '" + key + "'");
+      Preconditions.checkArgument(taskClass != null, "Class must be set for task '" + key + "'");
+      return new TaskDefinition(this);
+    }
+  }
 }
diff --git a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskExtension.java b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskExtension.java
index 92c3c7230de..8406650ef79 100644
--- a/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskExtension.java
+++ b/sonar-plugin-api/src/main/java/org/sonar/api/task/TaskExtension.java
@@ -22,9 +22,9 @@ package org.sonar.api.task;
 import org.sonar.api.Extension;
 
 /**
- * Task extension point.
+ * Task extension point
  *
- * @since 3.5
+ * @since 3.6
  */
 public interface TaskExtension extends Extension, TaskComponent {
 }
diff --git a/sonar-plugin-api/src/test/java/org/sonar/api/task/TaskDefinitionTest.java b/sonar-plugin-api/src/test/java/org/sonar/api/task/TaskDefinitionTest.java
new file mode 100644
index 00000000000..dcd581946aa
--- /dev/null
+++ b/sonar-plugin-api/src/test/java/org/sonar/api/task/TaskDefinitionTest.java
@@ -0,0 +1,100 @@
+/*
+ * Sonar, open source software quality management tool.
+ * Copyright (C) 2008-2012 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * Sonar is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * Sonar is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sonar; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02
+ */
+package org.sonar.api.task;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+
+import static org.fest.assertions.Assertions.assertThat;
+
+public class TaskDefinitionTest {
+
+  @Rule
+  public ExpectedException thrown = ExpectedException.none();
+
+  @Test
+  public void should_build() {
+    TaskDefinition def = TaskDefinition.builder().key("foo").taskClass(FooTask.class).description("Foo").build();
+    assertThat(def.key()).isEqualTo("foo");
+    assertThat(def.description()).isEqualTo("Foo");
+    assertThat(def.taskClass()).isEqualTo(FooTask.class);
+    assertThat(def.toString()).isEqualTo("Task foo[class=org.sonar.api.task.TaskDefinitionTest$FooTask, desc=Foo]");
+  }
+
+  @Test
+  public void test_equals_and_hashcode() {
+    TaskDefinition def1 = TaskDefinition.builder().key("one").taskClass(FooTask.class).description("Foo").build();
+    TaskDefinition def1bis = TaskDefinition.builder().key("one").taskClass(FooTask.class).description("Foo").build();
+    TaskDefinition def2 = TaskDefinition.builder().key("two").taskClass(FooTask.class).description("Foo").build();
+
+    assertThat(def1).isEqualTo(def1);
+    assertThat(def1).isEqualTo(def1bis);
+    assertThat(def2).isNotEqualTo(def1);
+    assertThat(def2).isNotEqualTo("one");
+    assertThat(def2).isNotEqualTo(null);
+
+    assertThat(def1.hashCode()).isEqualTo(def1.hashCode());
+    assertThat(def1.hashCode()).isEqualTo(def1bis.hashCode());
+  }
+
+  @Test
+  public void test_compare() {
+    TaskDefinition foo = TaskDefinition.builder().key("foo").taskClass(FooTask.class).description("Foo").build();
+    TaskDefinition bar = TaskDefinition.builder().key("bar").taskClass(FooTask.class).description("Bar").build();
+
+    assertThat(foo.compareTo(bar)).isGreaterThan(0);
+    assertThat(foo.compareTo(foo)).isEqualTo(0);
+    assertThat(bar.compareTo(foo)).isLessThan(0);
+  }
+
+  @Test
+  public void description_should_be_required() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Description must be set for task 'foo'");
+    TaskDefinition.builder().key("foo").taskClass(FooTask.class).build();
+  }
+
+  @Test
+  public void key_should_be_required() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Task key must be set");
+    TaskDefinition.builder().description("Foo").taskClass(FooTask.class).build();
+  }
+
+  @Test
+  public void key_should_not_contain_spaces() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Task key 'fo o' must match " + TaskDefinition.KEY_PATTERN);
+    TaskDefinition.builder().key("fo o").description("foo").taskClass(FooTask.class).build();
+  }
+
+  @Test
+  public void class_should_be_required() {
+    thrown.expect(IllegalArgumentException.class);
+    thrown.expectMessage("Class must be set for task 'foo'");
+    TaskDefinition.builder().key("foo").description("Foo").build();
+  }
+
+  private static class FooTask implements Task {
+    public void execute() {
+    }
+  }
+}