stream

const stream: Stream

What

stream represents the stream which is being processed at the time. The stream object is available in any script-based Processor, e.g. the JavaScript Processor.

How to use

You can access it directly without the need to instantiate it. It provides a number of functions which can - and sometimes have to - be invoked to control stream processing.

Please check the Stream documentation for more information.

Example

// Get stream information
const streamId = stream.getId();
const streamName = stream.getName();

// Emit a message to an output port
const outputPort = processor.getOutputPort('MyOutput');
stream.emit(message, outputPort);

// Log information
stream.logInfo('Processing stream: ' + streamName);
stream.logWarning('Unusual data encountered in stream');
stream.logError('An error occurred during stream processing');

// Get stream metadata
const metadata = stream.getMetadata();
const fileSize = metadata.data.Size;  // For a file-based stream

// Set stream properties
stream.setOutputName('new_stream_name');
stream.setOutputPath('/new/output/path');

// Request retry or rollback
if (errorCondition) {
    stream.requestRetry(Status.create(VENDOR, 'TEMPORARY_ERROR'), 30000);  // Retry after 30 seconds
}
if (fatalError) {
    stream.requestRollback(Status.create(VENDOR, 'FATAL_ERROR'));
}

// Using stream in lifecycle hooks
export function onStreamStart() {
    const streamId = stream.getId();
    const fileName = stream.getName();
    stream.logInfo('Started processing stream: ' + fileName);
}

export function onStreamEnd() {
    stream.logInfo('Finished processing stream: ' + fileName);
}

export function onMessage() {
    // Process the message
    // ...
    // Emit the processed message
    stream.emit(message, outputPort);
}

export function onCommit() {
    stream.logInfo('Stream ' + streamId + ' committed successfully');
}

export function onRollback() {
    stream.logError('Stream ' + streamId + ' rolled back due to errors');
}

Note: The exact methods and properties available on the stream object may vary depending on your specific layline.io configuration and the type of stream being processed. Always refer to the most up-to-date documentation provided by layline.io for the definitive guide on using the stream object in JavaScript scripts.

Global

Constant