jrosclient

http://portal2.atwebpages.com/jrosclient
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jrosclient is a Java client library that allows applications to interact with ROS (Robot Operating...
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### Start Android Emulator

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Command to launch a specific Android Virtual Device.

```bash
emulator -avd vm-android-14
```

--------------------------------

### Install Android APK

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Use ADB to install the jros1droid application package onto the emulator.

```bash
adb install id.jros1droid-v<VERSION>-debug.apk
```

--------------------------------

### Running the Publisher Application

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Commands to execute the PublisherApp depending on the dependency management setup.

```bash
java -cp "<JROSCLIENT_INSTALL_DIR>/libs/*" PublisherApp.java
```

```bash
depresolve io.github.lambdaprime:jros1client:8.0 --exec "java PublisherApp.java"
```

--------------------------------

### Subscribe to ROS Topics

Source: http://portal2.atwebpages.com/jrosclient/jrosclient-command.html

Example of publishing to a topic and subscribing to it using the jrosclient command.

```bash
rostopic pub -r 10 helloRos std_msgs/String "hello there"
```

```bash
jrosclient rostopic echo /helloRos id.jrosmessages.std_msgs.StringMessage
```

--------------------------------

### Execute SubscriberApp

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Commands to run the subscriber application depending on the installation method.

```bash
java -cp "<JROSCLIENT_INSTALL_DIR>/libs/*" SubscriberApp.java
```

```bash
depresolve io.github.lambdaprime:jros2client:9.0 --exec "java SubscriberApp.java"
```

--------------------------------

### Subscriber Output Examples

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Expected console output when receiving messages from the ROS topic.

```text
{ "data": "Hello ROS" }
{ "data": "Hello ROS" }
{ "data": "Hello ROS" }
```

```text
{ "data": "Hello ROS" }
{ "data": "hello there" }
```

--------------------------------

### Android Virtual Device Configuration Output

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Example output showing the configuration details of an Android Virtual Device.

```text
Available Android Virtual Devices:
    Name: vm-android-14
  Target: Default Android System Image
          Based on: Android API 34 Tag/ABI: default/x86_64
  Sdcard: 512 MB
```

--------------------------------

### Launch isaac_ros_jetson_stats

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Command to start the ROS 2 launch file for monitoring Jetson statistics.

```bash
ros2 launch isaac_ros_jetson_stats jtop.launch.py
```

--------------------------------

### Subscriber Execution Commands

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Commands to run the subscriber application depending on the installation method.

```bash
java -cp "<JROSCLIENT_INSTALL_DIR>/libs/*" SubscriberApp.java
```

```bash
depresolve io.github.lambdaprime:jros1client:8.0 --exec "java SubscriberApp.java"
```

--------------------------------

### Correct Field Initialization

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Example of a properly initialized field ensuring the object is serialized correctly.

```java
public Time stamp = new Time();
```

--------------------------------

### List Android Virtual Devices

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Use this command to verify available Android Virtual Devices before starting the emulator.

```bash
avdmanager list avd
```

--------------------------------

### Subscriber Output with Multiple Publishers

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Example output showing messages received from multiple publishers.

```text
{ "data": "Hello ROS" }
{ "data": "hello there" }
```

--------------------------------

### Manually install jros2client

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Extract the jros2client package to a local directory for use in Java scripts or jshell.

```bash
unzip -d <JROSCLIENT_INSTALL_DIR> jros2client.zip
```

--------------------------------

### Array Field Initialization

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Example of initializing an array field with an empty array to prevent serialization errors.

```java
public Point32Message[] points = new Point32Message[0];
```

--------------------------------

### Add jrosclient to PATH

Source: http://portal2.atwebpages.com/jrosclient/jrosclient-command.html

Commands to add the jrosclient installation directory to the system PATH for bash and zsh shells.

```bash
echo "export PATH=$PATH:<JROS1CLIENT_INSTALL_DIR>" >> ~/.bashrc
```

```zsh
echo "export PATH=$PATH:<JROS1CLIENT_INSTALL_DIR>" >> ~/.zshrc
```

--------------------------------

### Fixed Size Array Definition

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Example of defining a fixed-size array using the @Array annotation.

```java
@Array(size = 4)
public double[] coef = new double[0];
```

--------------------------------

### Incorrect Null Field Initialization

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Example of an incorrectly initialized field that will cause serialization issues due to null values.

```java
public Time stamp;
```

--------------------------------

### Build and Run diagnostics_otel

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Commands to clone the repository, build the project with Gradle, and execute the resulting JAR file.

```bash
git clone https://github.com/lambdaprime/jros2client
cd jros2client/jros2client.examples/diagnostics_otel
gradle clean build
```

```bash
java -jar build/libs/diagnostics_otel.jar
```

--------------------------------

### Publishing to a ROS 2 topic in Java

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Demonstrates creating a JRos2Client, registering a publisher for a topic, and sending StringMessage objects periodically.

```java
import id.jros2client.JRos2ClientConfiguration;
import id.jros2client.JRos2ClientFactory;
import id.jrosclient.TopicSubmissionPublisher;
import id.jrosmessages.std_msgs.StringMessage;

/**
 * Creates a new topic and publishes messages to it.
 */
public class PublisherApp {

    public static void main(String[] args) throws Exception {
        var configBuilder = new JRos2ClientConfiguration.Builder();
        // use configBuilder to override default parameters (network interface, RTPS settings etc)
        var client = new JRos2ClientFactory().createClient(configBuilder.build());
        String topicName = "/helloRos";
        var publisher = new TopicSubmissionPublisher<>(StringMessage.class, topicName);
        // register a new publisher for a new topic with ROS
        client.publish(publisher);
        while (true) {
            publisher.submit(new StringMessage().withData("Hello ROS"));
            System.out.println("Published");
            Thread.sleep(1000);
        }

        // usually we need to close client once we are done
        // but here we keep it open so that subscriber will keep
        // printing messages indefinitely
    }
}
```

--------------------------------

### Run ROS1 publisher

Source: http://portal2.atwebpages.com/jrosclient/ros_bridge.html

Command to publish string messages to the helloRos topic in a ROS1 environment.

```bash
rostopic pub -r 10 helloRos std_msgs/String "hello there"
```

--------------------------------

### Enable Debug Logging for ROS Clients

Source: http://portal2.atwebpages.com/jrosclient

Use these commands to run publisher applications with debug logging enabled for ROS2 and ROS1 respectively.

```bash
java -Djava.util.logging.config.file=jros2client-debug.properties -cp "libs/*" examples/PublisherApp.java
```

```bash
java -Djava.util.logging.config.file=jros1client-debug.properties -cp "libs/*" examples/PublisherApp.java
```

--------------------------------

### jrosclient Usage Syntax

Source: http://portal2.atwebpages.com/jrosclient/jrosclient-command.html

General syntax for executing the jrosclient command with available options.

```bash
jrosclient [--masterUrl MASTER_URL] [--nodePort NODE_PORT] [--truncate MAX_LENGTH] [--debug] <COMMAND> [args ...]
```

--------------------------------

### Initialize OpenTelemetry Meter

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Retrieves a global meter instance for the application.

```java
meter = GlobalOpenTelemetry.getMeter(DiagnosticsOpenTelemetryApp.class.getSimpleName());
```

--------------------------------

### Publisher Application Output

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Expected console output when the publisher is running successfully.

```text
Published
Published
Published
Published
...
```

--------------------------------

### Subscribe to ROS Diagnostics Topic

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Sets up a subscriber for the /diagnostics_agg topic to process incoming diagnostic messages.

```java
var configBuilder = new JRos2ClientConfiguration.Builder();
// use configBuilder to override default parameters (network interface, RTPS settings etc)
var client = new JRos2ClientFactory().createClient(
    configBuilder.build());
var topicName = "/diagnostics_agg";

// register a new subscriber with default QOS policies
// users can redefine QOS policies using overloaded version of subscribe() method
client.subscribe(new TopicSubscriber<>(DiagnosticArrayMessage.class, topicName) {
    @Override
    public void onNext(DiagnosticArrayMessage item) {
        System.out.println("New item received");
        try {
            emitToOpenTelemetry(item);
        } finally {
            // request next message
            getSubscription().get().request(1);
        }
    }
});
```

--------------------------------

### Subscribing to the Topic via rostopic

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Command and expected output to verify the published messages using the ROS CLI.

```bash
rostopic echo helloRos
```

```text
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
```

--------------------------------

### Available rostopic Commands

Source: http://portal2.atwebpages.com/jrosclient/jrosclient-command.html

Commands for echoing topic messages and listing system information.

```bash
rostopic echo [-n COUNT]
```

```bash
rostopic list
```

--------------------------------

### Publishing to a ROS topic in Java

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Creates a ROS topic and publishes string messages every second. Requires jros1client dependencies on the classpath.

```java
import id.jros1client.JRos1ClientConfiguration;
import id.jros1client.JRos1ClientFactory;
import id.jrosclient.TopicSubmissionPublisher;
import id.jrosmessages.std_msgs.StringMessage;

/** Creates a new topic and publishes messages to it. */
public class PublisherApp {

    public static void main(String[] args) throws Exception {
        var config = new JRos1ClientConfiguration();
        // host address where jrosclient is running and to which other ROS nodes
        // will communicate
        config.setHostAddress("localhost");
        // specify URL of the master node
        var client = new JRos1ClientFactory().createClient("http://localhost:11311/", config);
        String topicName = "helloRos";
        var publisher = new TopicSubmissionPublisher<>(StringMessage.class, topicName);
        // register a new publisher for a new topic with ROS
        client.publish(publisher);
        while (true) {
            publisher.submit(new StringMessage().withData("Hello ROS"));
            System.out.println("Published");
            Thread.sleep(1000);
        }

        // usually we need to close client once we are done
        // but here we keep it open so that subscriber will keep
        // printing messages indefinitely
    }
}
```

--------------------------------

### Subscribe to a ROS 2 topic in Java

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Implements a subscriber for the /helloRos topic using JRos2ClientFactory. Requires the jros2client library in the classpath.

```java
import id.jros2client.JRos2ClientConfiguration;
import id.jros2client.JRos2ClientFactory;
import id.jrosclient.TopicSubscriber;
import id.jrosmessages.std_msgs.StringMessage;

/**
 * Subscribes to ROS topic
 */
public class SubscriberApp {

    public static void main(String[] args) throws Exception {
        var configBuilder = new JRos2ClientConfiguration.Builder();
        // use configBuilder to override default parameters (network interface, RTPS settings etc)
        var client = new JRos2ClientFactory().createClient(configBuilder.build());
        var topicName = "/helloRos";
        // register a new subscriber with default QOS policies
        // users can redefine QOS policies using overloaded version of subscribe() method
        client.subscribe(
                new TopicSubscriber<>(StringMessage.class, topicName) {
                    @Override
                    public void onNext(StringMessage item) {
                        System.out.println(item);
                        // request next message
                        getSubscription().get().request(1);
                    }
                });

        // usually we need to close client once we are done
        // but here we keep it open so that subscriber will keep
        // printing messages indefinitely
    }
}
```

--------------------------------

### Define Jetson Statistics Metrics

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Defines the list of Jetson hardware statistics to be tracked.

```java
List<String> isaac_ros_jetson_stats = List.of(
    "/jtop/CPU/jetson_stats/temp/cpu",
    "/jtop/Board/pwmfan/PWM 0",
    "/jtop/Board/pwmfan/RPM 0",
    "/jtop/GPU/jetson_stats/gpu/gpu",
    "/jtop/GPU/jetson_stats/temp/gpu",
    "/jtop/GPU/gpu/Used",
    "/jtop/Memory/ram/Use");
```

--------------------------------

### Subscribing to topic via ROS 2 CLI

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Command and expected output for verifying the published messages using the ros2 echo utility.

```bash
ros2 topic echo helloRos std_msgs/String
```

```text
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
---
data: "Hello ROS"
```

--------------------------------

### Run ROS2 subscriber

Source: http://portal2.atwebpages.com/jrosclient/ros_bridge.html

Command to listen for string messages on the helloRos topic in a ROS2 environment.

```bash
ros2 topic echo helloRos std_msgs/String
```

--------------------------------

### Configure OpenTelemetry Elasticsearch Exporter

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Initializes a PeriodicMetricReader to export metrics to Elasticsearch every 3 seconds.

```java
/** Setup OpenTelemetry to send metrics to Elasticsearch */
private static void setupMetrics() {
    var metricReader =
        PeriodicMetricReader.builder(
            new ElasticsearchMetricExporter(
                    URI.create("ELASTICSEARCH_URL/diagnostics_otel"),
                    Optional.empty(),
                    Duration.ofSeconds(5),
                    true))
                .setInterval(Duration.ofSeconds(3))
                .build();
    var sdkMeterProvider =
        SdkMeterProvider.builder().registerMetricReader(metricReader).build();
    OpenTelemetrySdk.builder().setMeterProvider(sdkMeterProvider).buildAndRegisterGlobal();
}
```

--------------------------------

### Unzip jros1client package

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

Command to extract the jros1client distribution package to a specified directory.

```bash
unzip -d <JROSCLIENT_INSTALL_DIR> jros1client.zip
```

--------------------------------

### Publish to ROS 2 topic via CLI

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Command to publish a message to the /helloRos topic using the ROS 2 CLI tool.

```bash
ros2 topic pub -r 3 helloRos std_msgs/String 'data: "hello there"'
```

--------------------------------

### List Network Interfaces with jshell

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Use this jshell command to identify the correct network interface name for your system.

```java
jshell> NetworkInterface.networkInterfaces().forEach(System.out::println)
```

--------------------------------

### Java Dependencies for jros2client and OpenTelemetry

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Required dependencies for the jros2client library and OpenTelemetry API.

```gradle
implementation "io.github.lambdaprime:jros2client:10.0"
implementation "io.opentelemetry:opentelemetry-api:1.43.0"
```

--------------------------------

### Create Metric Gauges

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Registers a gauge for each defined Jetson statistic.

```java
Map<String, DoubleGauge> gauges = new HashMap<>();
isaac_ros_jetson_stats.stream()
    .forEach(stat -> gauges.put(stat, meter.gaugeBuilder(toMetricName(stat)).build()));
```

--------------------------------

### Subscriber Application Implementation

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros1client.html

A Java application that connects to a ROS master and subscribes to a specific topic to process incoming messages.

```java
import id.jros1client.JRos1ClientConfiguration;
import id.jros1client.JRos1ClientFactory;
import id.jrosclient.TopicSubscriber;
import id.jrosmessages.std_msgs.StringMessage;

/** Subscribes to ROS topic */
public class SubscriberApp {

    public static void main(String[] args) throws Exception {
        var config = new JRos1ClientConfiguration();
        // host address where jrosclient is running and to which other ROS nodes
        // will communicate
        config.setHostAddress("localhost");
        // specify URL of the master node
        var client = new JRos1ClientFactory().createClient("http://localhost:11311/");
        var topicName = "/helloRos";
        // register a new subscriber
        client.subscribe(
                new TopicSubscriber<>(StringMessage.class, topicName) {
                    @Override
                    public void onNext(StringMessage item) {
                        System.out.println(item);
                        // request next message
                        getSubscription().get().request(1);
                    }
                });

        // usually we need to close client once we are done
        // but here we keep it open so that subscriber will keep
        // printing messages indefinitely
    }
}
```

--------------------------------

### Verify message publication output

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Observe the console output to confirm that messages are being successfully published.

```text
Published
Published
Published
Published
Published
Published
Published
Published
Published
...
```

--------------------------------

### Configure Network Interface in jros2client

Source: http://portal2.atwebpages.com/jrosclient/Quick_Start_jros2client.html

Use JRos2ClientConfiguration to explicitly set the network interface when the default selection is incorrect.

```java
var configBuilder = new JRos2ClientConfiguration.Builder();
// run on network interface with name "eth0"
configBuilder.rtpsTalkConfiguration(
    new RtpsTalkConfiguration.Builder()
        .networkInterface("eth0")
        .build());
new JRos2ClientFactory().createClient(configBuilder.build());
```

--------------------------------

### Calculate ROS1 MD5 Sum

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Command to retrieve the MD5 sum required for ROS1 message definitions.

```bash
rosmsg md5 geometry_msgs/PolygonStamped
```

```text
c6be8f7dc3bee7fe9e8d296070f53340
```

--------------------------------

### Emit Metrics to OpenTelemetry

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Parses ROS diagnostic messages and updates the corresponding OpenTelemetry gauges.

```java
void emitToOpenTelemetry(DiagnosticArrayMessage item) {
    for (var s : item.status) {
        var name = s.name.data;
        for (var pair : s.values) {
            var keyName = pair.key.data;
            var fullName = name + "/" + keyName;
            var gauge = gauges.get(fullName);
            if (gauge == null) continue;
            try {
                var val = parseMeasurement(pair.value.data);
                gauge.set(val);
                System.out.println(fullName + "=" + val);
            } catch (Exception e) {
                System.err.format(
                    "Could not parse double value from %s: %s", pair, e.getMessage());
            }
        }
    }
}
```

--------------------------------

### Polygon ROS Definition

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

The ROS definition file content for geometry_msgs/Polygon.

```text
#A specification of a polygon where the first and last points are assumed to be connected
Point32[] points

```

--------------------------------

### Calculate ROS1 MD5 Sum

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Command to retrieve the MD5 sum for a ROS message type.

```bash
rosmsg md5 geometry_msgs/Polygon 
cd60a26494a087f577976f0329fa120e

```

--------------------------------

### PolygonStamped ROS Definition

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

The ROS definition file content for geometry_msgs/PolygonStamped.

```text
# This represents a Polygon with reference coordinate frame and timestamp
Header header
Polygon polygon

```

--------------------------------

### Define ROS1 PolygonStampedMessage

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Java class definition for the ROS1 geometry_msgs/PolygonStamped message, including the required MD5 sum metadata.

```java
import id.jros1messages.std_msgs.HeaderMessage;

/** Example of custom message definition */
@MessageMetadata(
        name = PolygonStampedMessage.NAME,
        fields = {"header", "polygon"},
        md5sum = "c6be8f7dc3bee7fe9e8d296070f53340")
public static class PolygonStampedMessage implements Message {

    static final String NAME = "geometry_msgs/PolygonStamped";

    public HeaderMessage header = new HeaderMessage();

    public PolygonMessage polygon = new PolygonMessage();

    public PolygonStampedMessage withPolygon(PolygonMessage polygon) {
        this.polygon = polygon;
        return this;
    }

    public PolygonStampedMessage withHeader(HeaderMessage header) {
        this.header = header;
        return this;
    }
}
```

--------------------------------

### ROS2 topic output

Source: http://portal2.atwebpages.com/jrosclient/ros_bridge.html

Expected output format when receiving forwarded messages in the ROS2 terminal.

```text
data: Hello ROS
---
data: Hello ROS
---
data: Hello ROS
---
data: Hello ROS
```

--------------------------------

### Elasticsearch Exporter Dependency

Source: http://portal2.atwebpages.com/jrosclient/diagnostics_otel

Optional dependency required to export OpenTelemetry metrics to an Elasticsearch backend.

```gradle
implementation "io.github.lambdaprime:id.opentelemetry-exporters-pack:4.0"
```

--------------------------------

### Define ROS2 PolygonStampedMessage

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Java class definition for the ROS2 geometry_msgs/PolygonStamped message using the jros2messages Header.

```java
import id.jros2messages.std_msgs.HeaderMessage;

/** Example of custom message definition */
@MessageMetadata(
        name = PolygonStampedMessage.NAME,
        fields = {"header", "polygon"})
public static class PolygonStampedMessage implements Message {

    static final String NAME = "geometry_msgs/PolygonStamped";

    public HeaderMessage header = new HeaderMessage();

    public PolygonMessage polygon = new PolygonMessage();

    public PolygonStampedMessage withPolygon(PolygonMessage polygon) {
        this.polygon = polygon;
        return this;
    }

    public PolygonStampedMessage withHeader(HeaderMessage header) {
        this.header = header;
        return this;
    }
}
```

--------------------------------

### Define Polygon Java Message Class

Source: http://portal2.atwebpages.com/jrosclient/Defining_messages.html

Implementation of a Java class for the geometry_msgs/Polygon message type using @MessageMetadata.

```java
/** Example of custom message definition */
@MessageMetadata(
        name = PolygonMessage.NAME,
        /*fields = {"points"} /* This parameter is optional because message has only one field */
        md5sum = "cd60a26494a087f577976f0329fa120e")
public static class PolygonMessage implements Message {

    static final String NAME = "geometry_msgs/Polygon";

    public Point32Message[] points = new Point32Message[0];

    public PolygonMessage withPoints(Point32Message[] points) {
        this.points = points;
        return this;
    }
}
```
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