PackedMessage

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id: py-PackedMessage

PackedMessage

A memory-efficient compressed representation of a Message. Use PackedMessage when you need to retain many messages in memory (e.g., buffering, aggregation, or caching) and want to reduce memory overhead.

Create a PackedMessage by calling message.pack(). Unpack it back to a full Message when you need to access or modify the data.

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At a Glance

# Pack a message for efficient storage
packed = message.pack()

# Store in a buffer or cache
message_buffer.append(packed)

# Later: unpack and process
restored = packed.unpack()
stream.emit(restored, OUTPUT_PORT)

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Properties

Property	Type	Description
type	DataDictionary	Reference to the data dictionary used when packing

packed = message.pack()
stream.logInfo(f'Packed type: {packed.type}')

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Methods

unpack()

Restores the packed message to a full Message instance.

Returns: Message

packed = message.pack()
restored = packed.unpack()

# restored is a full Message with all methods available
restored.getString(dataDictionary.type.Order.ID)
restored.addStatus(Severity.INFO, Status.create(VENDOR, 'RESTORED'))

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When to Use

Scenario	Approach
Buffering messages for batch processing	Pack to reduce memory
Caching messages in a queue service	Pack before storing
Aggregating many records before emitting	Pack intermediate results
Passing messages between processors	Use regular Message (no packing needed)

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Complete Example

buffer = []
BATCH_SIZE = 100

def on_message():
    # Pack and buffer
    buffer.append(message.pack())

    # When buffer is full, process batch
    if len(buffer) >= BATCH_SIZE:
        process_batch(buffer)
        buffer.clear()

def on_stream_end():
    # Process remaining messages
    if len(buffer) > 0:
        process_batch(buffer)

def process_batch(packed_messages):
    for packed in packed_messages:
        msg = packed.unpack()
        # Process...
        stream.emit(msg, OUTPUT_PORT)

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See Also

• Message#pack — Create a PackedMessage from a Message
• Message#clone — Alternative: create a full copy instead of packing