Package org.mockserver.llm.codec

Class BedrockEventStreamEncoder

java.lang.Object

org.mockserver.llm.codec.BedrockEventStreamEncoder

public final class BedrockEventStreamEncoder
extends Object

Encoder and decoder for the AWS event-stream binary message format (application/vnd.amazon.eventstream).

Each message has the following layout:

   4 bytes  — total byte length (big-endian)
   4 bytes  — headers byte length (big-endian)
   4 bytes  — prelude CRC32 (of the first 8 bytes)
   N bytes  — headers
   M bytes  — payload
   4 bytes  — message CRC32 (of everything up to this point)
 

For Bedrock InvokeModelWithResponseStream, each "chunk" event carries headers :event-type=chunk, :content-type=application/json, :message-type=event, and the payload is {"bytes":"<base64(chunkJson)>"}.

This class uses only JDK APIs (CRC32, Base64) and introduces no new Maven dependencies.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	BedrockEventStreamEncoder.DecodedMessage	A decoded event-stream message with parsed headers and raw payload.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CONTENT_TYPE	The MIME type for AWS event-stream framing.

Method Summary

Modifier and Type	Method	Description
static List<BedrockEventStreamEncoder.DecodedMessage>	decode(byte[] data)	Decode a concatenated event-stream byte array into individual messages.
static byte[]	encodeChunk(String chunkJson)	Encode a single model chunk (JSON string) into one AWS event-stream binary message.
static byte[]	encodeMessage(Map<String,String> headers, byte[] payload)	Encode a full event-stream binary message with the given headers and payload.
static byte[]	encodeStream(List<String> chunks)	Concatenate multiple chunk JSON strings into a single event-stream byte array (one binary message per chunk, concatenated).

Methods inherited from class java.lang.Object

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

Field Details

CONTENT_TYPE

public static final String CONTENT_TYPE

The MIME type for AWS event-stream framing.

See Also:

• Constant Field Values

Method Details

encodeChunk

public static byte[] encodeChunk(String chunkJson)

Encode a single model chunk (JSON string) into one AWS event-stream binary message. The chunk JSON is base64-encoded and wrapped in a {"bytes":"<base64>"} payload, matching Bedrock's InvokeModelWithResponseStream wire format.

Parameters:

chunkJson - the model's streaming chunk JSON (e.g. an Anthropic SSE data payload)

Returns:

the complete binary event-stream message

encodeMessage

public static byte[] encodeMessage(Map<String,String> headers,
 byte[] payload)

Encode a full event-stream binary message with the given headers and payload.

Parameters:

headers - string-typed headers (name to value)

payload - the raw payload bytes

Returns:

the complete binary message

encodeStream

public static byte[] encodeStream(List<String> chunks)

Concatenate multiple chunk JSON strings into a single event-stream byte array (one binary message per chunk, concatenated).

Parameters:

chunks - the ordered list of model chunk JSON strings

Returns:

concatenated event-stream messages

decode

public static List<BedrockEventStreamEncoder.DecodedMessage> decode(byte[] data)

Decode a concatenated event-stream byte array into individual messages.

Parameters:

data - the raw event-stream bytes

Returns:

ordered list of decoded messages

Throws:

IllegalArgumentException - if any CRC32 check fails or data is malformed