Passthrough

Unstable API 0.7.0 @project-lakechain/passthrough

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The Passthrough middleware acts, as its name implies, as a passthrough for document events. Its main purpose is to log document events and their associated metadata.

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➡️ Logging Events

To use this middleware, you import it in your CDK stack and instantiate it as part of a pipeline.

import { Passthrough } from '@project-lakechain/passthrough';
import { CacheStorage } from '@project-lakechain/core';

class Stack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string) {
    // The cache storage.
    const cache = new CacheStorage(this, 'Cache');

    // The passthrough middleware.
    const passthrough = new Passthrough.Builder()
      .withScope(this)
      .withIdentifier('Passthrough')
      .withCacheStorage(cache)
      .withSource(source) // 👈 Specify a data source
      .build();
  }
}

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Resolving Metadata

As seen in the Events section, metadata associated with a document event can contain Pointers to other documents. You can configure the Passthrough middleware to resolve those pointers and log their value in CloudWatch logs for debugging purposes.

const passthrough = new Passthrough.Builder()
  .withScope(this)
  .withIdentifier('Passthrough')
  .withCacheStorage(cache)
  .withSource(source)
  .withResolveMetadata(true)
  .build();

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🏗️ Architecture

The Passthrough middleware executes within a Lambda compute, consumes input events, logs their information to AWS CloudWatch Logs and passes through the events to the next middlewares in the pipeline.

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🏷️ Properties

Supported Inputs

Mime Type	Description
*/*	The passthrough middleware can consume any type of document.

Supported Outputs

Mime Type	Description
*/*	The passthrough middleware can produce any type of document.

Supported Compute Types

Type	Description
CPU	This middleware is based on a Lambda architecture.

📖 Examples

• Delay Pipeline - An example showcasing how to delay a pipeline execution.