<dependency>
    <groupId>io.a2a.sdk</groupId>
    <artifactId>a2a-java-sdk-core</artifactId>
    <version>0.2.3</version>
</dependency>

import io.a2a.spec.AgentCapabilities;
import io.a2a.spec.AgentCard;
import io.a2a.spec.AgentSkill;
import io.a2a.spec.PublicAgentCard;
...

@ApplicationScoped
public class WeatherAgentCardProducer {
    
    @Produces
    @PublicAgentCard
    public AgentCard agentCard() {
        return new AgentCard.Builder()
                .name("Weather Agent")
                .description("Helps with weather")
                .url("http://localhost:10001")
                .version("1.0.0")
                .capabilities(new AgentCapabilities.Builder()
                        .streaming(true)
                        .pushNotifications(false)
                        .stateTransitionHistory(false)
                        .build())
                .defaultInputModes(Collections.singletonList("text"))
                .defaultOutputModes(Collections.singletonList("text"))
                .skills(Collections.singletonList(new AgentSkill.Builder()
                        .id("weather_search")
                        .name("Search weather")
                        .description("Helps with weather in city, or states")
                        .tags(Collections.singletonList("weather"))
                        .examples(List.of("weather in LA, CA"))
                        .build()))
                .build();
    }
}

import io.a2a.server.agentexecution.AgentExecutor;
import io.a2a.server.agentexecution.RequestContext;
import io.a2a.server.events.EventQueue;
import io.a2a.server.tasks.TaskUpdater;
import io.a2a.spec.JSONRPCError;
import io.a2a.spec.Message;
import io.a2a.spec.Part;
import io.a2a.spec.Task;
import io.a2a.spec.TaskNotCancelableError;
import io.a2a.spec.TaskState;
import io.a2a.spec.TextPart;
...

@ApplicationScoped
public class WeatherAgentExecutorProducer {

    @Inject
    WeatherAgent weatherAgent;

    @Produces
    public AgentExecutor agentExecutor() {
        return new WeatherAgentExecutor(weatherAgent);
    }

    private static class WeatherAgentExecutor implements AgentExecutor {

        private final WeatherAgent weatherAgent;

        public WeatherAgentExecutor(WeatherAgent weatherAgent) {
            this.weatherAgent = weatherAgent;
        }

        @Override
        public void execute(RequestContext context, EventQueue eventQueue) throws JSONRPCError {
            TaskUpdater updater = new TaskUpdater(context, eventQueue);

            // mark the task as submitted and start working on it
            if (context.getTask() == null) {
                updater.submit();
            }
            updater.startWork();

            // extract the text from the message
            String userMessage = extractTextFromMessage(context.getMessage());

            // call the weather agent with the user's message
            String response = weatherAgent.chat(userMessage);

            // create the response part
            TextPart responsePart = new TextPart(response, null);
            List<Part<?>> parts = List.of(responsePart);

            // add the response as an artifact and complete the task
            updater.addArtifact(parts, null, null, null);
            updater.complete();
        }

        @Override
        public void cancel(RequestContext context, EventQueue eventQueue) throws JSONRPCError {
            Task task = context.getTask();

            if (task.getStatus().state() == TaskState.CANCELED) {
                // task already cancelled
                throw new TaskNotCancelableError();
            }

            if (task.getStatus().state() == TaskState.COMPLETED) {
                // task already completed
                throw new TaskNotCancelableError();
            }

            // cancel the task
            TaskUpdater updater = new TaskUpdater(context, eventQueue);
            updater.cancel();
        }

        private String extractTextFromMessage(Message message) {
            StringBuilder textBuilder = new StringBuilder();
            if (message.getParts() != null) {
                for (Part part : message.getParts()) {
                    if (part instanceof TextPart textPart) {
                        textBuilder.append(textPart.getText());
                    }
                }
            }
            return textBuilder.toString();
        }
    }
}

<dependency>
    <groupId>io.a2a.sdk</groupId>
    <artifactId>a2a-java-sdk-server-jakarta</artifactId>
    <version>${io.a2a.sdk.version}</version>
</dependency>

<dependency>
    <groupId>io.a2a.sdk</groupId>
    <artifactId>a2a-java-sdk-server-quarkus</artifactId>
    <version>${io.a2a.sdk.version}</version>
</dependency>

// Create an A2AClient (the URL specified is the server agent's URL, be sure to replace it with the actual URL of the A2A server you want to connect to)
A2AClient client = new A2AClient("http://localhost:1234");

// Send a text message to the A2A server agent
Message message = A2A.toUserMessage("tell me a joke"); // the message ID will be automatically generated for you
MessageSendParams params = new MessageSendParams.Builder()
        .message(message)
        .build();
SendMessageResponse response = client.sendMessage(params);        

Message message = A2A.toUserMessage("tell me a joke", "message-1234"); // messageId is message-1234

// Retrieve the task with id "task-1234"
GetTaskResponse response = client.getTask("task-1234");

// You can also specify the maximum number of items of history for the task
// to include in the response
GetTaskResponse response = client.getTask(new TaskQueryParams("task-1234", 10));

// Cancel the task we previously submitted with id "task-1234"
CancelTaskResponse response = client.cancelTask("task-1234");

// You can also specify additional properties using a map
Map<String, Object> metadata = ...        
CancelTaskResponse response = client.cancelTask(new TaskIdParams("task-1234", metadata));

// Get task push notification configuration
GetTaskPushNotificationConfigResponse response = client.getTaskPushNotificationConfig("task-1234");

// You can also specify additional properties using a map
Map<String, Object> metadata = ...
GetTaskPushNotificationConfigResponse response = client.getTaskPushNotificationConfig(new TaskIdParams("task-1234", metadata));

// Set task push notification configuration
PushNotificationConfig pushNotificationConfig = new PushNotificationConfig.Builder()
        .url("https://example.com/callback")
        .authenticationInfo(new AuthenticationInfo(Collections.singletonList("jwt"), null))
        .build();
SetTaskPushNotificationResponse response = client.setTaskPushNotificationConfig("task-1234", pushNotificationConfig);

// Send a text message to the remote agent
Message message = A2A.toUserMessage("tell me some jokes"); // the message ID will be automatically generated for you
MessageSendParams params = new MessageSendParams.Builder()
        .message(message)
        .build();

// Create a handler that will be invoked for Task, Message, TaskStatusUpdateEvent, and TaskArtifactUpdateEvent
Consumer<StreamingEventKind> eventHandler = event -> {...};

// Create a handler that will be invoked if an error is received
Consumer<JSONRPCError> errorHandler = error -> {...};

// Create a handler that will be invoked in the event of a failure
Runnable failureHandler = () -> {...};

// Send the streaming message to the remote agent
client.sendStreamingMessage(params, eventHandler, errorHandler, failureHandler);

// Create a handler that will be invoked for Task, Message, TaskStatusUpdateEvent, and TaskArtifactUpdateEvent
Consumer<StreamingEventKind> eventHandler = event -> {...};

// Create a handler that will be invoked if an error is received
Consumer<JSONRPCError> errorHandler = error -> {...};

// Create a handler that will be invoked in the event of a failure
Runnable failureHandler = () -> {...};

// Resubscribe to an ongoing task with id "task-1234"
TaskIdParams taskIdParams = new TaskIdParams("task-1234");
client.resubscribeToTask("request-1234", taskIdParams, eventHandler, errorHandler, failureHandler);

AgentCard serverAgentCard = client.getAgentCard();

// http://localhost:1234 is the base URL for the agent whose card we want to retrieve
AgentCard agentCard = A2A.getAgentCard("http://localhost:1234");