Class RemoteA2AAgent

java.lang.Object

com.google.adk.workflow.BaseNode

com.google.adk.agents.BaseAgent

com.google.adk.a2a.agent.RemoteA2AAgent

All Implemented Interfaces:

Node

public class RemoteA2AAgent
extends BaseAgent

Agent that communicates with a remote A2A agent via an A2A client.

The remote agent can be specified directly by providing an AgentCard to the builder, or it can be resolved automatically using the provided A2A client.

Key responsibilities of this agent include:

• Agent card resolution and validation
• Converting ADK session history events into A2A requests (Message)
• Handling streaming and non-streaming responses from the A2A client
• Buffering and aggregating streamed response chunks into ADK Events
• Converting A2A client responses back into ADK format

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	RemoteA2AAgent.AgentCardResolutionError	Exception thrown when the agent card cannot be resolved.
static class	RemoteA2AAgent.Builder	Builder for RemoteA2AAgent.
static class	RemoteA2AAgent.TypeError	Exception thrown when a type error occurs.

Method Summary

Modifier and Type	Method	Description
static RemoteA2AAgent.Builder	builder()
boolean	isStreaming()
protected io.reactivex.rxjava3.core.Flowable<Event>	runAsyncImpl(InvocationContext invocationContext)	Agent-specific asynchronous logic.
protected io.reactivex.rxjava3.core.Flowable<Event>	runLiveImpl(InvocationContext invocationContext)	Agent-specific synchronous logic.
AgentEnums.AgentOrigin	toolOrigin()	Returns the origin of the tool when this agent is used as a tool.

Methods inherited from class BaseAgent

afterAgentCallback, beforeAgentCallback, canonicalAfterAgentCallbacks, canonicalBeforeAgentCallbacks, close, findAgent, findSubAgent, fromConfig, parentAgent, parentAgent, rootAgent, runAsync, runLive, runNode, subAgents

Modifier and Type	Method	Description
com.google.common.collect.ImmutableList<? extends Callbacks.AfterAgentCallback>	afterAgentCallback()
com.google.common.collect.ImmutableList<? extends Callbacks.BeforeAgentCallback>	beforeAgentCallback()
com.google.common.collect.ImmutableList<? extends Callbacks.AfterAgentCallback>	canonicalAfterAgentCallbacks()	The resolved afterAgentCallback field as a list.
com.google.common.collect.ImmutableList<? extends Callbacks.BeforeAgentCallback>	canonicalBeforeAgentCallbacks()	The resolved beforeAgentCallback field as a list.
io.reactivex.rxjava3.core.Completable	close()	Closes all sub-agents.
Optional<BaseAgent>	findAgent(String name)	Finds an agent (this or descendant) by name.
Optional<BaseAgent>	findSubAgent(String name)	Recursively search sub agent by name.
static BaseAgent	fromConfig(BaseAgentConfig config, String configAbsPath)	Creates a new agent instance from a configuration object.
BaseAgent	parentAgent()	Retrieves the parent agent in the agent tree.
protected void	parentAgent(BaseAgent parentAgent)	Sets the parent agent.
BaseAgent	rootAgent()	Returns the root agent for this agent by traversing up the parent chain.
io.reactivex.rxjava3.core.Flowable<Event>	runAsync(InvocationContext parentContext)	Runs the agent asynchronously.
io.reactivex.rxjava3.core.Flowable<Event>	runLive(InvocationContext parentContext)	Runs the agent synchronously.
io.reactivex.rxjava3.core.Flowable<Event>	runNode(Context context, @Nullable Object nodeInput)	Runs this agent as a workflow node through its BaseAgent.runAsync(InvocationContext) lifecycle, including its callbacks.
List<? extends BaseAgent>	subAgents()

Methods inherited from class BaseNode

config, description, inputSchema, name, outputSchema, rerunOnResume, stateSchema, waitForOutput

Modifier and Type	Method	Description
NodeConfig	config()	Returns the node's retry policy and execution timeout.
String	description()	Returns what the node does, for humans and for a model that may call it.
Optional<com.google.genai.types.Schema>	inputSchema()	Returns the schema the node's input must match.
final String	name()	Returns the name that identifies the node within its graph.
Optional<com.google.genai.types.Schema>	outputSchema()	Returns the schema that the node's output value must match.
boolean	rerunOnResume()	Returns true if a resumed node runs again from scratch, rather than completing with the resuming answer as its output.
Optional<com.google.genai.types.Schema>	stateSchema()	Returns the schema declaring the state keys the node uses.
boolean	waitForOutput()	Returns true if the node stays re-triggerable until it produces an output or a route, instead of completing when its run completes.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface Node

requiresAllPredecessors

Modifier and Type	Method	Description
default boolean	requiresAllPredecessors()	Returns true if the node runs only once every predecessor has completed, receiving all their outputs keyed by node name, as a fan-in node does.

Method Details

builder

public static RemoteA2AAgent.Builder builder()

isStreaming

public boolean isStreaming()

runAsyncImpl

protected io.reactivex.rxjava3.core.Flowable<Event> runAsyncImpl(InvocationContext invocationContext)

Description copied from class: BaseAgent

Agent-specific asynchronous logic.

Specified by:

runAsyncImpl in class BaseAgent

Parameters:

invocationContext - Current invocation context.

Returns:

stream of agent-generated events.

runLiveImpl

protected io.reactivex.rxjava3.core.Flowable<Event> runLiveImpl(InvocationContext invocationContext)

Description copied from class: BaseAgent

Agent-specific synchronous logic.

Specified by:

runLiveImpl in class BaseAgent

Parameters:

invocationContext - Current invocation context.

Returns:

stream of agent-generated events.

toolOrigin

public AgentEnums.AgentOrigin toolOrigin()

Description copied from class: BaseAgent

Returns the origin of the tool when this agent is used as a tool.

Overrides:

toolOrigin in class BaseAgent

Returns:

the tool origin, defaults to "BASE_AGENT".