Extract constants into separate libarary.

pkg/analysis_server/lib/src/domain_server.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library domain.server;
 
 import 'package:analysis_server/src/analysis_server.dart';
+import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
 
 /**
  * Instances of the class [ServerDomainHandler] implement a [RequestHandler]
  * that handles requests in the server domain.
  */
 class ServerDomainHandler implements RequestHandler {
   /**
-   * The name of the `server.getVersion` request.
-   */
-  static const String GET_VERSION_METHOD = 'server.getVersion';
-
-  /**
-   * The name of the `server.setSubscriptions` request.
-   */
-  static const String SET_SUBSCRIPTIONS_METHOD = 'server.setSubscriptions';
-
-  /**
-   * The name of the `server.shutdown` request.
-   */
-  static const String SHUTDOWN_METHOD = 'server.shutdown';
-
-  /**
-   * The name of the `subscriptions` parameter.
-   */
-  static const String SUBSCRIPTIONS_PARAMETER = 'subscriptions';
-
-  /**
-   * The name of the version result value.
-   */
-  static const String VERSION_RESULT = 'version';
-
-  /**
    * The analysis server that is using this handler to process requests.
    */
   final AnalysisServer server;
 
   /**
    * Initialize a newly created handler to handle requests for the given [server].
    */
   ServerDomainHandler(this.server);
 
   @override
   Response handleRequest(Request request) {
     try {
       String requestName = request.method;
-      if (requestName == GET_VERSION_METHOD) {
+      if (requestName == METHOD_GET_VERSION) {
         return getVersion(request);
-      } else if (requestName == SET_SUBSCRIPTIONS_METHOD) {
+      } else if (requestName == METHOD_SET_SUBSCRIPTIONS) {
           return setSubscriptions(request);
-      } else if (requestName == SHUTDOWN_METHOD) {
+      } else if (requestName == METHOD_SHUTDOWN) {
         return shutdown(request);
       }
     } on RequestFailure catch (exception) {
       return exception.response;
     }
     return null;
   }
 
   /**
    * Subscribe for services.
    *
    * All previous subscriptions are replaced by the given set of subscriptions.
    */
   Response setSubscriptions(Request request) {
-    RequestDatum subDatum = request.getRequiredParameter(SUBSCRIPTIONS_PARAMETER);
+    RequestDatum subDatum = request.getRequiredParameter(SUBSCRIPTIONS);
     server.serverServices = subDatum.asEnumSet(ServerService.VALUES);
     return new Response(request.id);
   }
 
   // TODO(scheglov) remove or move to the 'analysis' domain
 //  /**
 //   * Create a new context in which analysis can be performed. The context that
 //   * is created will persist until server.deleteContext is used to delete it.
 //   * Clients, therefore, are responsible for managing the lifetime of contexts.
 //   */
@@ skipping 51 matching lines @@
     server.running = false;
     Response response = new Response(request.id);
     return response;
   }
 
   /**
    * Return the version number of the analysis server.
    */
   Response getVersion(Request request) {
     Response response = new Response(request.id);
-    response.setResult(VERSION_RESULT, '0.0.1');
+    response.setResult(VERSION, '0.0.1');
     return response;
   }
 }