Introducing content-filtering topics

.github/workflows/windows-build-and-test-compatibility.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        node-version: [14.21.2, 16.19.0, 18.14.2, 19.X]
+        node-version: [14.21.2, 16.19.0, 18.14.1, 19.X]
         ros_distribution:
           - foxy
           - humble

docs/EFFICIENCY.md

@@ -1,7 +1,9 @@
 # Tips for efficent use of rclnodejs
-While our benchmarks place rclnodejs performance at or above that of [rclpy](https://github.com/ros2/rclpy) we recommend appyling efficient coding and configuration practices where applicable. 
+
+While our benchmarks place rclnodejs performance at or above that of [rclpy](https://github.com/ros2/rclpy) we recommend appyling efficient coding and configuration practices where applicable.
 
 ## Tip-1: Disable Parameter Services
+
 The typical ROS 2 node creation process includes creating an internal parameter service who's job is to fulfill requests for parameter meta-data and to set and update node parameters. If your ROS 2 node does not support public parameters then you can save the resources consumed by the parameter service. Disable the node parameter service by setting the `NodeOption.startParameterServices` property to false as shown below:
 
 ```
@@ -13,16 +15,54 @@ let node = new Node(nodeName, namespace, Context.defaultContext(), options);
 ```
 
 ## Tip-2: Disable LifecycleNode Lifecycle Services
+
 The LifecycleNode constructor creates 5 life-cycle services to support the ROS 2 lifecycle specification. If your LifecycleNode instance will not be operating in a managed-node context consider disabling the lifecycle services via the LifecycleNode constructor as shown:
 
 ```
 let enableLifecycleCommInterface = false;
 
 let node = new LifecycleNode(
-  nodeName, 
+  nodeName,
   namespace,
-  Context.defaultContext, 
+  Context.defaultContext,
   NodeOptions.defaultOptions,
-  enableLifecycleCommInterface 
+  enableLifecycleCommInterface
 );
 ```
+
+## Tip-3: Use Content-filtering Subscriptions
+
+The ROS Humble release introduced content-filtering topics
+which enable a subscription to limit the messages it receives
+to a subset of interest. While the application of the a content-filter
+is specific to the DDS/RMW vendor, the general approach is to apply
+filtering on the publisher side. This can reduce network bandwidth
+for pub-sub communications and message processing and memory
+overhead of rclnodejs nodes.
+
+Note: Be sure to confirm that your RMW implementation supports
+content-filter before attempting to use it. In cases where content-filtering
+is not supported your Subscription will simply ignore your filter and
+continue operating with no filtering.
+
+Example:
+
+```
+  // create a content-filter to limit incoming messages to
+  // only those with temperature > 75C.
+  const options = rclnodejs.Node.getDefaultOptions();
+  options.contentFilter = {
+    expression: 'temperature > %0',
+    parameters: [75],
+  };
+
+  node.createSubscription(
+    'sensor_msgs/msg/Temperature',
+    'temperature',
+    options,
+    (temperatureMsg) => {
+      console.log(`EMERGENCY temperature detected: ${temperatureMsg.temperature}`);
+    }
+  );
+
+```

example/publisher-content-filter-example.js

@@ -0,0 +1,53 @@
+// Copyright (c) 2023 Wayne Parrott. All rights reserved.
+//
+// Licensed 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.
+
+'use strict';
+
+/* eslint-disable camelcase */
+
+const rclnodejs = require('../index.js');
+
+async function main() {
+  await rclnodejs.init();
+  const node = new rclnodejs.Node('publisher_content_filter_example_node');
+  const publisher = node.createPublisher(
+    'sensor_msgs/msg/Temperature',
+    'temperature'
+  );
+
+  let count = 0;
+  setInterval(function () {
+    let temperature = (Math.random() * 100).toFixed(2);
+
+    publisher.publish({
+      header: {
+        stamp: {
+          sec: 123456,
+          nanosec: 789,
+        },
+        frame_id: 'main frame',
+      },
+      temperature: temperature,
+      variance: 0,
+    });
+
+    console.log(
+      `Publish temerature message-${++count}: ${temperature} degrees`
+    );
+  }, 750);
+
+  node.spin();
+}
+
+main();

example/subscription-content-filter-example.js

@@ -0,0 +1,95 @@
+// Copyright (c) 2023 Wayne Parrott. All rights reserved.
+//
+// Licensed 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.
+
+'use strict';
+
+const { assertDefined } = require('dtslint/bin/util.js');
+const rclnodejs = require('../index.js');
+
+/**
+ * This example demonstrates the use of content-filtering
+ * topics (subscriptions) that were introduced in ROS 2 Humble.
+ * See the following resources for content-filtering in ROS:
+ * @see {@link Node#options}
+ * @see {@link Node#createSubscription}
+ * @see {@link https://www.omg.org/spec/DDS/1.4/PDF|DDS 1.4 specification, Annex B}
+ *
+ * Use publisher-content-filter-example.js to generate example messages.
+ *
+ * To see all published messages (filterd + unfiltered) run this
+ * from commandline:
+ *
+ *   ros2 topic echo temperature
+ *
+ * @return {undefined}
+ */
+async function main() {
+  await rclnodejs.init();
+  const node = new rclnodejs.Node('subscription_message_example_node');
+
+  let param = 50;
+
+  // create a content-filter to limit incoming messages to
+  // only those with temperature > paramC.
+  const options = rclnodejs.Node.getDefaultOptions();
+  options.contentFilter = {
+    expression: 'temperature > %0',
+    parameters: [param],
+  };
+
+  let count = 0;
+  let subscription;
+  try {
+    subscription = node.createSubscription(
+      'sensor_msgs/msg/Temperature',
+      'temperature',
+      options,
+      (temperatureMsg) => {
+        console.log(`Received temperature message-${++count}: 
+${temperatureMsg.temperature}C`);
+        if (count % 5 === 0) {
+          if (subscription.hasContentFilter()) {
+            console.log('Clearing filter');
+            subscription.clearContentFilter();
+          } else {
+            param += 10;
+            console.log('Update topic content-filter, temperature > ', param);
+            const contentFilter = {
+              expression: 'temperature > %0',
+              parameters: [param],
+            };
+            subscription.setContentFilter(contentFilter);
+          }
+          console.log(
+            'Content-filtering enabled: ',
+            subscription.hasContentFilter()
+          );
+        }
+      }
+    );
+
+    if (!subscription.hasContentFilter()) {
+      console.log('Content-filtering is not enabled on subscription.');
+    }
+  } catch (error) {
+    console.error('Unable to create content-filtering subscription.');
+    console.error(
+      'Please ensure your content-filter expression and parameters are well-formed.'
+    );
+  }
+
+  node.spin();
+}
+
+main();

index.js

@@ -15,6 +15,7 @@
 'use strict';
 
 const DistroUtils = require('./lib/distro.js');
+const RMWUtils = require('./lib/rmw.js');
 const { Clock, ROSClock } = require('./lib/clock.js');
 const ClockType = require('./lib/clock_type.js');
 const compareVersions = require('compare-versions');
@@ -136,6 +137,9 @@ let rcl = {
   /** {@link QoS} class */
   QoS: QoS,
 
+  /** {@link RMWUtils} */
+  RMWUtils: RMWUtils,
+
   /** {@link ROSClock} class */
   ROSClock: ROSClock,
 

lib/distro.js

@@ -42,7 +42,7 @@ const DistroUtils = {
    * @return {number} Return the rclnodejs distro identifier
    */
   getDistroId: function (distroName) {
-    const dname = distroName ? distroName : this.getDistroName();
+    const dname = distroName ? distroName.toLowerCase() : this.getDistroName();
 
     return DistroNameIdMap.has(dname)
       ? DistroNameIdMap.get(dname)

lib/node.js

@@ -464,12 +464,7 @@ class Node extends rclnodejs.ShadowNode {
     }
 
     if (options === undefined) {
-      options = {
-        enableTypedArray: true,
-        isRaw: false,
-        qos: QoS.profileDefault,
-      };
-      return options;
+      return Node.getDefaultOptions();
     }
 
     if (options.enableTypedArray === undefined) {
@@ -608,7 +603,7 @@ class Node extends rclnodejs.ShadowNode {
    */
 
   /**
-   * Create a Subscription.
+   * Create a Subscription with optional content-filtering.
    * @param {function|string|object} typeClass - The ROS message class,
         OR a string representing the message class, e.g. 'std_msgs/msg/String',
         OR an object representing the message class, e.g. {package: 'std_msgs', type: 'msg', name: 'String'}
@@ -617,9 +612,18 @@ class Node extends rclnodejs.ShadowNode {
    * @param {boolean} options.enableTypedArray - The topic will use TypedArray if necessary, default: true.
    * @param {QoS} options.qos - ROS Middleware "quality of service" settings for the subscription, default: QoS.profileDefault.
    * @param {boolean} options.isRaw - The topic is serialized when true, default: false.
+   * @param {object} [options.contentFilter=undefined] - The content-filter, default: undefined.
+   *  Confirm that your RMW supports content-filtered topics before use. 
+   * @param {string} options.contentFilter.expression - Specifies the criteria to select the data samples of
+   *  interest. It is similar to the WHERE part of an SQL clause.
+   * @param {string[]} [options.contentFilter.parameters=undefined] - Array of strings that give values to
+   *  the ‘parameters’ (i.e., "%n" tokens) in the filter_expression. The number of supplied parameters must
+   *  fit with the requested values in the filter_expression (i.e., the number of %n tokens). default: undefined.
    * @param {SubscriptionCallback} callback - The callback to be call when receiving the topic subscribed. The topic will be an instance of null-terminated Buffer when options.isRaw is true.
    * @return {Subscription} - An instance of Subscription.
+   * @throws {ERROR} - May throw an RMW error if content-filter is malformed. 
    * @see {@link SubscriptionCallback}
+   * @see {@link https://www.omg.org/spec/DDS/1.4/PDF|Content-filter details at DDS 1.4 specification, Annex B}
    */
   createSubscription(typeClass, topic, options, callback) {
     if (typeof typeClass === 'string' || typeof typeClass === 'object') {
@@ -1645,4 +1649,25 @@ class Node extends rclnodejs.ShadowNode {
   }
 }
 
+/**
+ * Create an Options instance initialized with default values.
+ * @returns {Options} - The new initialized instance.
+ * @static
+ * @example
+ * {
+ *   enableTypedArray: true,
+ *   isRaw: false,
+ *   qos: QoS.profileDefault,
+ *   contentFilter: undefined,
+ * }
+ */
+Node.getDefaultOptions = function () {
+  return {
+    enableTypedArray: true,
+    isRaw: false,
+    qos: QoS.profileDefault,
+    contentFilter: undefined,
+  };
+};
+
 module.exports = Node;

lib/rmw.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const DistroUtils = require('./distro');
+
+const RMWNames = {
+  FASTRTPS: 'rmw_fastrtps_cpp',
+  CONNEXT: 'rmw_connext_cpp',
+  CYCLONEDDS: 'rmw_cyclonedds_cpp',
+  GURUMDDS: 'rmw_gurumdds_cpp',
+};
+
+const DefaultRosRMWNameMap = new Map();
+DefaultRosRMWNameMap.set('eloquent', RMWNames.FASTRTPS);
+DefaultRosRMWNameMap.set('foxy', RMWNames.FASTRTPS);
+DefaultRosRMWNameMap.set('galactic', RMWNames.CYCLONEDDS);
+DefaultRosRMWNameMap.set('humble', RMWNames.FASTRTPS);
+DefaultRosRMWNameMap.set('rolling', RMWNames.FASTRTPS);
+
+const RMWUtils = {
+  RMWNames: RMWNames,
+
+  getRMWName: function () {
+    return process.env.RMW_IMPLEMENTATION
+      ? process.env.RMW_IMPLEMENTATION
+      : DefaultRosRMWNameMap.get(DistroUtils.getDistroName());
+  },
+};
+
+module.exports = RMWUtils;