Implement new event streams API

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/AwsEventEncoderFactory.java

@@ -15,6 +15,7 @@
 import software.amazon.smithy.java.core.serde.event.EventEncoderFactory;
 import software.amazon.smithy.java.core.serde.event.EventStreamingException;
 import software.amazon.smithy.java.core.serde.event.FrameEncoder;
+import software.amazon.smithy.java.core.serde.event.FrameTransformer;
 
 /**
  * A {@link EventEncoderFactory} for AWS events.
@@ -24,19 +25,22 @@ public final class AwsEventEncoderFactory implements EventEncoderFactory<AwsEven
     private final Schema schema;
     private final Codec codec;
     private final String payloadMediaType;
+    private final FrameTransformer<AwsEventFrame> transformer;
     private final Function<Throwable, EventStreamingException> exceptionHandler;
 
     private AwsEventEncoderFactory(
             InitialEventType initialEventType,
             Schema schema,
             Codec codec,
             String payloadMediaType,
+            FrameTransformer<AwsEventFrame> transformer,
             Function<Throwable, EventStreamingException> exceptionHandler
     ) {
         this.initialEventType = Objects.requireNonNull(initialEventType, "initialEventType");
         this.schema = Objects.requireNonNull(schema, "schema").isMember() ? schema.memberTarget() : schema;
         this.codec = Objects.requireNonNull(codec, "codec");
         this.payloadMediaType = Objects.requireNonNull(payloadMediaType, "payloadMediaType");
+        this.transformer = Objects.requireNonNull(transformer, "transformer");
         this.exceptionHandler = Objects.requireNonNull(exceptionHandler, "exceptionHandler");
     }
 
@@ -53,12 +57,14 @@ public static AwsEventEncoderFactory forInputStream(
             InputEventStreamingApiOperation<?, ?, ?> operation,
             Codec codec,
             String payloadMediaType,
+            FrameTransformer<AwsEventFrame> transformer,
             Function<Throwable, EventStreamingException> exceptionHandler
     ) {
         return new AwsEventEncoderFactory(InitialEventType.INITIAL_REQUEST,
                 operation.inputStreamMember(),
                 codec,
                 payloadMediaType,
+                transformer,
                 exceptionHandler);
     }
 
@@ -75,18 +81,25 @@ public static AwsEventEncoderFactory forOutputStream(
             OutputEventStreamingApiOperation<?, ?, ?> operation,
             Codec codec,
             String payloadMediaType,
+            FrameTransformer<AwsEventFrame> transformer,
             Function<Throwable, EventStreamingException> exceptionHandler
     ) {
         return new AwsEventEncoderFactory(InitialEventType.INITIAL_RESPONSE,
                 operation.outputStreamMember(),
                 codec,
                 payloadMediaType,
+                transformer,
                 exceptionHandler);
     }
 
     @Override
     public EventEncoder<AwsEventFrame> newEventEncoder() {
-        return new AwsEventShapeEncoder(initialEventType, schema, codec, payloadMediaType, exceptionHandler);
+        return new AwsEventShapeEncoder(initialEventType,
+                schema,
+                codec,
+                payloadMediaType,
+                transformer,
+                exceptionHandler);
     }
 
     @Override

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/AwsEventShapeDecoder.java

@@ -9,7 +9,6 @@
 import java.time.Instant;
 import java.util.Map;
 import java.util.Objects;
-import java.util.concurrent.Flow;
 import java.util.function.Supplier;
 import software.amazon.eventstream.HeaderValue;
 import software.amazon.eventstream.Message;
@@ -21,6 +20,7 @@
 import software.amazon.smithy.java.core.serde.ShapeDeserializer;
 import software.amazon.smithy.java.core.serde.SpecificShapeDeserializer;
 import software.amazon.smithy.java.core.serde.event.EventDecoder;
+import software.amazon.smithy.java.core.serde.event.EventStream;
 
 /**
  * A decoder for AWS events
@@ -36,7 +36,6 @@ public final class AwsEventShapeDecoder<E extends SerializableStruct, IR extends
     private final Supplier<ShapeBuilder<E>> eventBuilder;
     private final Schema eventSchema;
     private final Codec codec;
-    private volatile Flow.Publisher<SerializableStruct> publisher;
 
     AwsEventShapeDecoder(
             InitialEventType initialEventType,
@@ -54,19 +53,9 @@ public final class AwsEventShapeDecoder<E extends SerializableStruct, IR extends
 
     @Override
     public SerializableStruct decode(AwsEventFrame frame) {
-        var message = frame.unwrap();
-        var eventType = getEventType(message);
-        if (initialEventType.value().equals(eventType)) {
-            return decodeInitialResponse(frame);
-        }
         return decodeEvent(frame);
     }
 
-    @Override
-    public void onPrepare(Flow.Publisher<SerializableStruct> publisher) {
-        this.publisher = publisher;
-    }
-
     private E decodeEvent(AwsEventFrame frame) {
         var message = frame.unwrap();
         var eventType = getEventType(message);
@@ -85,12 +74,13 @@ private E decodeEvent(AwsEventFrame frame) {
         return builder.build();
     }
 
-    private IR decodeInitialResponse(AwsEventFrame frame) {
+    @Override
+    public IR decodeInitialEvent(AwsEventFrame frame, EventStream<?> eventStream) {
         var message = frame.unwrap();
         var builder = initialEventBuilder.get();
-        var publisherMember = getPublisherMember(builder.schema());
+        var publisherMember = getEventStreamMember(builder.schema());
         // Set the publisher member
-        var responseDeserializer = new InitialResponseDeserializer(publisherMember, publisher);
+        var responseDeserializer = new InitialResponseDeserializer(publisherMember, eventStream);
         builder.deserialize(responseDeserializer);
         // Deserialize the rest of the members if any
         var headers = message.getHeaders();
@@ -100,7 +90,7 @@ private IR decodeInitialResponse(AwsEventFrame frame) {
         return builder.build();
     }
 
-    private Schema getPublisherMember(Schema schema) {
+    private Schema getEventStreamMember(Schema schema) {
         for (var member : schema.members()) {
             if (member.memberTarget().hasTrait(TraitKey.STREAMING_TRAIT)) {
                 return member;
@@ -115,16 +105,16 @@ private String getEventType(Message message) {
 
     static class InitialResponseDeserializer extends SpecificShapeDeserializer {
         private final Schema publisherMember;
-        private final Flow.Publisher<? extends SerializableStruct> publisher;
+        private final EventStream<?> eventStream;
 
-        InitialResponseDeserializer(Schema publisherMember, Flow.Publisher<? extends SerializableStruct> publisher) {
+        InitialResponseDeserializer(Schema publisherMember, EventStream<?> eventStream) {
             this.publisherMember = publisherMember;
-            this.publisher = publisher;
+            this.eventStream = eventStream;
         }
 
         @Override
-        public Flow.Publisher<? extends SerializableStruct> readEventStream(Schema schema) {
-            return publisher;
+        public EventStream<? extends SerializableStruct> readEventStream(Schema schema) {
+            return eventStream;
         }
 
         @Override

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/AwsEventShapeEncoder.java

@@ -26,6 +26,7 @@
 import software.amazon.smithy.java.core.serde.SpecificShapeSerializer;
 import software.amazon.smithy.java.core.serde.event.EventEncoder;
 import software.amazon.smithy.java.core.serde.event.EventStreamingException;
+import software.amazon.smithy.java.core.serde.event.FrameTransformer;
 import software.amazon.smithy.model.shapes.ShapeId;
 
 public final class AwsEventShapeEncoder implements EventEncoder<AwsEventFrame> {
@@ -35,13 +36,15 @@ public final class AwsEventShapeEncoder implements EventEncoder<AwsEventFrame> {
     private final String payloadMediaType;
     private final Map<String, BiFunction<OutputStream, Map<String, HeaderValue>, ShapeSerializer>> possibleTypes;
     private final Map<ShapeId, Schema> possibleExceptions;
+    private final FrameTransformer<AwsEventFrame> frameTransformer;
     private final Function<Throwable, EventStreamingException> exceptionHandler;
 
     public AwsEventShapeEncoder(
             InitialEventType initialEventType,
             Schema eventSchema,
             Codec codec,
             String payloadMediaType,
+            FrameTransformer<AwsEventFrame> frameTransformer,
             Function<Throwable, EventStreamingException> exceptionHandler
     ) {
         this.initialEventType = Objects.requireNonNull(initialEventType, "initialEventType");
@@ -51,6 +54,7 @@ public AwsEventShapeEncoder(
                 codec,
                 initialEventType.value());
         this.possibleExceptions = possibleExceptions(Objects.requireNonNull(eventSchema, "eventSchema"));
+        this.frameTransformer = Objects.requireNonNull(frameTransformer, "frameTransformer");
         this.exceptionHandler = Objects.requireNonNull(exceptionHandler, "exceptionHandler");
     }
 
@@ -62,7 +66,8 @@ public AwsEventFrame encode(SerializableStruct item) {
         headers.put(":message-type", HeaderValue.fromString("event"));
         headers.put(":event-type", HeaderValue.fromString(typeHolder.get()));
         headers.put(":content-type", HeaderValue.fromString(payloadMediaType));
-        return new AwsEventFrame(new Message(headers, payload));
+        var frame = new AwsEventFrame(new Message(headers, payload));
+        return frameTransformer.apply(frame);
     }
 
     private byte[] encodeInput(

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/AwsFrameDecoder.java

@@ -24,7 +24,7 @@ public AwsFrameDecoder(FrameTransformer<AwsEventFrame> transformer) {
     public List<AwsEventFrame> decode(ByteBuffer buffer) {
         decoder.feed(buffer);
         var messages = decoder.getDecodedMessages();
-        var result = new ArrayList<AwsEventFrame>();
+        var result = new ArrayList<AwsEventFrame>(messages.size());
         for (var message : messages) {
             var event = new AwsEventFrame(message);
             var transformed = transformer.apply(event);

aws/aws-event-streams/src/main/java/software/amazon/smithy/java/aws/events/RpcEventStreamsUtil.java

@@ -5,16 +5,14 @@
 
 package software.amazon.smithy.java.aws.events;
 
-import java.nio.ByteBuffer;
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.Flow;
 import software.amazon.smithy.java.core.schema.Schema;
 import software.amazon.smithy.java.core.schema.SerializableStruct;
 import software.amazon.smithy.java.core.schema.TraitKey;
 import software.amazon.smithy.java.core.serde.event.EventDecoderFactory;
 import software.amazon.smithy.java.core.serde.event.EventEncoderFactory;
-import software.amazon.smithy.java.core.serde.event.EventStreamFrameDecodingProcessor;
-import software.amazon.smithy.java.core.serde.event.EventStreamFrameEncodingProcessor;
+import software.amazon.smithy.java.core.serde.event.EventStream;
+import software.amazon.smithy.java.core.serde.event.InternalEventStreamReader;
+import software.amazon.smithy.java.core.serde.event.InternalEventStreamWriter;
 import software.amazon.smithy.java.io.datastream.DataStream;
 
 /**
@@ -24,47 +22,36 @@ public final class RpcEventStreamsUtil {
 
     private RpcEventStreamsUtil() {}
 
-    public static Flow.Publisher<ByteBuffer> bodyForEventStreaming(
+    @SuppressWarnings("unchecked")
+    public static DataStream bodyForEventStreaming(
             EventEncoderFactory<AwsEventFrame> eventStreamEncodingFactory,
             SerializableStruct input
     ) {
-        Flow.Publisher<SerializableStruct> eventStream = input.getMemberValue(streamingMember(input.schema()));
-        return EventStreamFrameEncodingProcessor.create(eventStream, eventStreamEncodingFactory, input);
-    }
-
-    // TODO: Make more synchronous
-    public static <O extends SerializableStruct> O deserializeResponse(
-            EventDecoderFactory<AwsEventFrame> eventDecoderFactory,
-            DataStream bodyDataStream
-    ) {
-        var result = new CompletableFuture<O>();
-        var processor = EventStreamFrameDecodingProcessor.create(bodyDataStream, eventDecoderFactory);
-
-        // A subscriber to serialize the initial event.
-        processor.subscribe(new Flow.Subscriber<>() {
-            @Override
-            public void onSubscribe(Flow.Subscription subscription) {
-                subscription.request(1);
-            }
-
+        EventStream<SerializableStruct> eventStream = input.getMemberValue(streamingMember(input.schema()));
+        InternalEventStreamWriter<SerializableStruct, SerializableStruct, AwsEventFrame> writer =
+                InternalEventStreamWriter.toInternal(eventStream);
+        writer.bootstrap(new InternalEventStreamWriter.Bootstrap<>() {
             @Override
-            @SuppressWarnings("unchecked")
-            public void onNext(SerializableStruct item) {
-                result.complete((O) item);
+            public EventEncoderFactory<AwsEventFrame> encoder() {
+                return eventStreamEncodingFactory;
             }
 
             @Override
-            public void onError(Throwable throwable) {
-                result.completeExceptionally(throwable);
-            }
-
-            @Override
-            public void onComplete() {
-                result.completeExceptionally(new RuntimeException("Unexpected event stream completion"));
+            public SerializableStruct initialEvent() {
+                return input;
             }
         });
+        return writer.toDataStream();
+    }
 
-        return result.join();
+    public static <O extends SerializableStruct> O deserializeResponse(
+            EventDecoderFactory<AwsEventFrame> eventDecoderFactory,
+            DataStream bodyDataStream
+    ) {
+        var reader = InternalEventStreamReader.<O, SerializableStruct, AwsEventFrame>newReader(bodyDataStream,
+                eventDecoderFactory,
+                true);
+        return reader.readInitialEvent();
     }
 
     private static Schema streamingMember(Schema schema) {
@@ -75,5 +62,4 @@ private static Schema streamingMember(Schema schema) {
         }
         throw new IllegalArgumentException("No streaming member found");
     }
-
 }

aws/aws-event-streams/src/test/java/software/amazon/smithy/java/aws/events/AwsEventShapeDecoderTest.java

@@ -35,7 +35,7 @@ public void testDecodeInitialResponse() {
         var frame = new AwsEventFrame(message);
 
         // Act
-        var struct = createDecoder().decode(frame);
+        var struct = createDecoder().decodeInitialEvent(frame, null);
 
         // Assert
         assertInstanceOf(TestOperationOutput.class, struct);

aws/aws-event-streams/src/test/java/software/amazon/smithy/java/aws/events/AwsEventShapeEncoderTest.java

@@ -20,6 +20,7 @@
 import software.amazon.smithy.java.aws.events.model.TestOperationInput;
 import software.amazon.smithy.java.core.serde.Codec;
 import software.amazon.smithy.java.core.serde.event.EventStreamingException;
+import software.amazon.smithy.java.core.serde.event.FrameTransformer;
 import software.amazon.smithy.java.json.JsonCodec;
 
 class AwsEventShapeEncoderTest {
@@ -135,6 +136,7 @@ static AwsEventShapeEncoder createEncoder() {
                 TestOperation.instance().inputStreamMember(), // event schema
                 createJsonCodec(), // codec
                 "text/json",
+                FrameTransformer.identity(),
                 (e) -> new EventStreamingException("InternalServerException", "Internal Server Error"));
     }