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Java bindings for the AWS IoT Core Service
/**
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0.
*/
package software.amazon.awssdk.eventstreamrpc;
import software.amazon.awssdk.crt.eventstream.ClientConnectionContinuation;
import software.amazon.awssdk.crt.eventstream.ClientConnectionContinuationHandler;
import software.amazon.awssdk.crt.eventstream.Header;
import software.amazon.awssdk.crt.eventstream.HeaderType;
import software.amazon.awssdk.crt.eventstream.MessageFlags;
import software.amazon.awssdk.crt.eventstream.MessageType;
import software.amazon.awssdk.eventstreamrpc.model.EventStreamJsonMessage;
import software.amazon.awssdk.eventstreamrpc.model.EventStreamOperationError;
import java.util.LinkedList;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.logging.Logger;
/**
* Not sure how public we need to make this class
*/
public class EventStreamRPCClient {
private static final Logger LOGGER = Logger.getLogger(EventStreamRPCClient.class.getName());
private final EventStreamRPCConnection connection;
/**
* Creates a new EventStreamRPCClient
* @param connection The connection for the EventStreamRPCClient to use
*/
public EventStreamRPCClient(EventStreamRPCConnection connection) {
if (connection == null) {
throw new IllegalArgumentException("Cannot create eventstream RPC client with null connection");
}
this.connection = connection;
}
/**
* Work horse of all operations, streaming or otherwise.
* @param The request type
* @param The response type
* @param The streaming request type
* @param The streaming response type
* @param operationModelContext The operation context
* @param request The request
* @param streamResponseHandler The streaming handler
* @return The operation result
*/
public
OperationResponse doOperationInvoke(
OperationModelContext operationModelContext,
final ReqType request, Optional> streamResponseHandler) {
if (operationModelContext.isStreamingOperation() && !streamResponseHandler.isPresent()) {
//Even if an operation does not have a streaming response (has streaming input), a
//stream is physically bidirectional, and even if a streaming response isn't allowed
//the other side may still send an error through the open stream.
throw new IllegalArgumentException(operationModelContext.getOperationName() + " is a streaming operation. Must have a streaming response handler!");
}
final CompletableFuture responseFuture = new CompletableFuture<>();
final AtomicBoolean isContinuationClosed = new AtomicBoolean(true);
final ClientConnectionContinuation continuation = connection.newStream(new ClientConnectionContinuationHandler() {
boolean initialResponseReceived = false;
@Override
protected void onContinuationMessage(List headers, byte[] payload, MessageType messageType, int messageFlags) {
final Optional applicationModelType = headers.stream()
.filter(header -> header.getName().equals(EventStreamRPCServiceModel.SERVICE_MODEL_TYPE_HEADER)
&& header.getHeaderType().equals(HeaderType.String))
.map(header -> header.getValueAsString())
.findFirst();
//first message back must parse into immediate response unless it's an error
//follow on messages are stream response handler intended
if (messageType.equals(MessageType.ApplicationMessage)) {
//important following not else if
if (applicationModelType.isPresent()) {
handleData(applicationModelType.get(), payload, !initialResponseReceived, responseFuture, streamResponseHandler,
operationModelContext, continuation, isContinuationClosed);
}
//intentionally not else if here. We can have data, and the terminate flag set
if ((messageFlags & MessageFlags.TerminateStream.getByteValue()) != 0) {
this.close();
handleClose(initialResponseReceived, responseFuture, streamResponseHandler);
} else if (!applicationModelType.isPresent()) {
handleError(new UnmappedDataException(initialResponseReceived ? operationModelContext.getResponseApplicationModelType() :
operationModelContext.getStreamingResponseApplicationModelType().get()), initialResponseReceived,
responseFuture, streamResponseHandler, continuation, isContinuationClosed);
}
initialResponseReceived = true;
} else if (messageType.equals(MessageType.ApplicationError)) {
final Optional> errorClass =
operationModelContext.getServiceModel().getApplicationModelClass(applicationModelType.orElse(""));
if (!errorClass.isPresent()) {
LOGGER.severe(String.format("Could not map error from service. Incoming error type: "
+ applicationModelType.orElse("null")));
handleError(new UnmappedDataException(applicationModelType.orElse("null")),
!initialResponseReceived, responseFuture, streamResponseHandler, continuation, isContinuationClosed);
} else {
try {
final EventStreamOperationError error = (EventStreamOperationError) operationModelContext.getServiceModel().fromJson(errorClass.get(), payload);
handleError(error, !initialResponseReceived, responseFuture, streamResponseHandler, continuation, isContinuationClosed);
} catch (Exception e) { //shouldn't be possible, but this is an error on top of an error
}
}
//TODO: application errors always have TerminateStream flag set?
//first close the stream immediately if the other side hasn't already done so
if ((messageFlags & MessageFlags.TerminateStream.getByteValue()) != 0) {
try {
this.close();
//is this call needed?
handleClose(initialResponseReceived, responseFuture, streamResponseHandler);
} catch (Exception e) {
LOGGER.warning(String.format("Exception thrown closing stream on application error received %s: %s",
e.getClass().getName(), e.getMessage()));
}
}
} else if (messageType == MessageType.Ping) {
//echo back ping messages to be nice to server, can these happen on continuations?
continuation.sendMessage(headers, payload, MessageType.PingResponse, messageFlags);
} else if (messageType == MessageType.PingResponse) { //do nothing on ping response
} else if (messageType == MessageType.ServerError) {
//TODO: exception should route to response handler here, also is or will be "InternalError" soon
LOGGER.severe(operationModelContext.getOperationName() + " server error received");
this.close(); //underlying connection callbacks should handle things appropriately
} else if (messageType == MessageType.ProtocolError) { //do nothing on ping response
LOGGER.severe(operationModelContext.getOperationName() + " protocol error received");
this.close(); //underlying connection callbacks should handle things appropriately but close continuation either way
} else {
//unexpected message type received on stream
handleError(new InvalidDataException(messageType), !initialResponseReceived, responseFuture,
streamResponseHandler, continuation, isContinuationClosed);
try {
sendClose(continuation, isContinuationClosed).whenComplete((res, ex) -> {
if (ex != null) {
LOGGER.warning(String.format("Sending close on invalid message threw %s: %s",
ex.getClass().getCanonicalName(), ex.getMessage()));
}
});
} catch (Exception e) {
LOGGER.warning(String.format("Sending close on invalid message threw %s: %s",
e.getClass().getCanonicalName(), e.getMessage()));
}
}
}
@Override
protected void onContinuationClosed() {
super.onContinuationClosed();
handleClose(initialResponseReceived, responseFuture, streamResponseHandler);
}
});
isContinuationClosed.compareAndSet(false, true);
final List headers = new LinkedList<>();
headers.add(Header.createHeader(EventStreamRPCServiceModel.CONTENT_TYPE_HEADER,
EventStreamRPCServiceModel.CONTENT_TYPE_APPLICATION_JSON));
headers.add(Header.createHeader(EventStreamRPCServiceModel.SERVICE_MODEL_TYPE_HEADER,
operationModelContext.getRequestApplicationModelType()));
final byte[] payload = operationModelContext.getServiceModel().toJson(request);
final CompletableFuture messageFlushFuture = continuation.activate(operationModelContext.getOperationName(),
headers, payload, MessageType.ApplicationMessage, 0);
final OperationResponse response = new OperationResponse(operationModelContext, continuation,
responseFuture, messageFlushFuture);
return response;
}
/**
* Sends an empty close message on the open stream.
* @param continuation continuation to send the close message on
* @return CompletableFuture indicating flush of the close message.
*/
private CompletableFuture sendClose(final ClientConnectionContinuation continuation, final AtomicBoolean isClosed) {
if (isClosed.compareAndSet(false, true)) {
return continuation.sendMessage(null, null,
MessageType.ApplicationMessage, MessageFlags.TerminateStream.getByteValue());
} else {
LOGGER.warning("Stream already closed"); //May help debug extra closes? May remove to avoid noise
return CompletableFuture.completedFuture(null);
}
}
private
void handleClose(boolean isInitial, CompletableFuture responseFuture,
final Optional> streamResponseHandler) {
if (isInitial && !responseFuture.isDone()) {
//response future should have completed because either an error has already been thrown using it,
//or the data has already come back. This combination is a problem state that suggests we're closing
//before having any server response
responseFuture.completeExceptionally(new RuntimeException("Closed received before any service operation response!"));
}
else if (streamResponseHandler.isPresent()) {
//The only valid way to respond to a close after request-response is via stream handler.
//This is a strange detail where a request->response operation doesn't really care or see
//the stream closing unless it uses a stream response handler.
try {
streamResponseHandler.get().onStreamClosed();
} catch (Exception e) {
LOGGER.warning(String.format("Client handler onStreamClosed() threw %s: %s",
e.getClass().getCanonicalName(), e.getMessage()));
}
}
}
private
void handleData(String applicationModelType, byte[] payload, boolean isInitial, CompletableFuture responseFuture,
final Optional> streamResponseHandler,
final OperationModelContext operationModelContext,
ClientConnectionContinuation continuation,
final AtomicBoolean isClosed) {
if (isInitial) {
//mismatch between type on the wire and type expected by the operation
if (!applicationModelType.equals(operationModelContext.getResponseApplicationModelType())) {
handleError(new UnmappedDataException(applicationModelType, operationModelContext.getResponseTypeClass()),
isInitial, responseFuture, streamResponseHandler, continuation, isClosed);
return;
}
RespType responseObj = null;
try {
responseObj = operationModelContext.getServiceModel().fromJson(operationModelContext.getResponseTypeClass(), payload);
} catch (Exception e) {
handleError(new DeserializationException(payload, e), isInitial, responseFuture, streamResponseHandler, continuation, isClosed);
return; //we're done if we can't deserialize
}
//complete normally
responseFuture.complete(responseObj);
} else {
//mismatch between type on the wire and type expected by the operation
if (!applicationModelType.equals(operationModelContext.getStreamingResponseApplicationModelType().get())) {
handleError(new UnmappedDataException(applicationModelType, operationModelContext.getStreamingResponseTypeClass().get()),
isInitial, responseFuture, streamResponseHandler, continuation, isClosed);
return;
}
StrRespType strResponseObj = null;
try {
strResponseObj = operationModelContext.getServiceModel().fromJson(
operationModelContext.getStreamingResponseTypeClass().get(), payload);
} catch (Exception e) {
handleError(new DeserializationException(payload, e), isInitial, responseFuture, streamResponseHandler, continuation, isClosed);
return; //we're done if we can't deserialize
}
try {
streamResponseHandler.get().onStreamEvent(strResponseObj);
} catch (Exception e) {
handleError(e, isInitial, responseFuture, streamResponseHandler, continuation, isClosed);
}
}
}
/**
* Handle error and based on result may close stream
*/
private
void handleError(Throwable t, boolean isInitial, final CompletableFuture responseFuture,
final Optional> streamResponseHandler,
ClientConnectionContinuation continuation,
final AtomicBoolean isClosed) {
if (!isInitial && !streamResponseHandler.isPresent()) {
throw new IllegalArgumentException("Cannot process error handling for stream without a stream response handler set!");
}
if (isInitial) {
responseFuture.completeExceptionally(t);
//failure on initial response future always closes stream
} else {
try {
if (streamResponseHandler.get().onStreamError(t)) {
sendClose(continuation, isClosed).whenComplete((res, ex) -> {
handleClose(isInitial, responseFuture, streamResponseHandler);
});
}
} catch (Exception e) {
LOGGER.warning(String.format("Stream response handler threw exception %s: %s",
e.getClass().getCanonicalName(), e.getMessage()));
sendClose(continuation, isClosed).whenComplete((res, ex) -> {
handleClose(isInitial, responseFuture, streamResponseHandler);
});
}
}
}
}
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