Haskell Client Library for the Nakadi Event Broker
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README.md

nakadi-client Hackage version Stackage version Build Status

About

nakadi-client is a BSD2/BSD3 licensed Haskell client library for interacting with the Nakadi event broker system developed by Zalando. The streaming is built on top of Conduit.

Please note that the API is not considered stable yet.

nakadi-client provides:

  • Docker based test suite testing against the official Nakadi docker image.

  • A type-safe API for interacting with Nakadi. For example, the name of an event type has type EventTypeName, not Text or something generic. Correct types for values like CursorOffset are provided (which must be treated as opaque strings).

  • Integrated and configurable retry mechanism.

  • Conduit based interfaces for streaming events.

  • Support for temporary subscriptions.

  • Convenient Subscription API interface (subscriptionProcess & subscriptionProcessConduit), which frees the user from any manual bookkeeping.

  • Mechanism for registering callbacks for logging and token injection.

Example

Example code showing how to dump a subscription:

dumpSubscription :: (MonadLogger m, MonadNakadi IO m) => Nakadi.SubscriptionId -> m ()
dumpSubscription subscriptionId =
  Nakadi.subscriptionProcess Nothing subscriptionId processBatch

  where processBatch :: MonadLogger m => Nakadi.SubscriptionEventStreamBatch Value -> m ()
        processBatch batch =
          logInfoN (tshow batch)