Metrics

The Metrics class provides access to performance counters and operational metrics. It is available globally as metrics in every JavaScript processor.

Currently supports counters — more metric types may be added in future releases.

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At a Glance

// Get or create a counter
const processed = metrics.getCounter('orders.processed');
const errors = metrics.getCounter('orders.errors');

// Update counters
processed.increment();
errors.increment(5);

// Read values
stream.logInfo(`Processed: ${processed.count}`);

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Methods

getCounter(name)

Retrieves or creates a counter metric.

Parameter	Type	Description
name	string	Counter identifier

Returns: Counter

const totalMessages = metrics.getCounter('stream.messages.total');
const failedMessages = metrics.getCounter('stream.messages.failed');

totalMessages.increment();
if (hasError) {
    failedMessages.increment();
}

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Complete Example

let OUTPUT_PORT;
let ERROR_PORT;

export function onInit() {
    OUTPUT_PORT = processor.getOutputPort('Output');
    ERROR_PORT  = processor.getOutputPort('Error');
}

export function onMessage() {
    const processed = metrics.getCounter('workflow.records.processed');
    const errors    = metrics.getCounter('workflow.records.errors');

    try {
        validateAndTransform(message);
        processed.increment();
        stream.emit(message, OUTPUT_PORT);
    } catch (err) {
        errors.increment();
        message.addStatus(Severity.ERROR, Status.create(VENDOR, 'PROCESSING_FAILED'));
        stream.emit(message, ERROR_PORT);
    }
}

export function onStreamEnd() {
    const processed = metrics.getCounter('workflow.records.processed');
    const errors    = metrics.getCounter('workflow.records.errors');

    const total = processed.count + errors.count;
    const rate = total > 0 ? (processed.count / total * 100).toFixed(1) : 0;

    stream.logInfo(`Stream complete: ${processed.count} ok, ${errors.count} errors (${rate}% success)`);
}

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See Also

• Counter — Counter operations (increment, decrement, chaining)