supernova: Apache Pulsar client for Haskell

[ apache, library, network ] [ Propose Tags ]

Supernova is an Apache Pulsar client that implements the specified TCP protocol.

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Versions [RSS] [faq] 0.0.1, 0.0.2, 0.0.3
Dependencies async (>=2.2.2 && <2.3), base (>=4.13.0 && <4.14), bifunctor (>=0.1.0 && <0.2), binary (>=0.8.7 && <0.9), bytestring (>=0.10.10 && <0.11), crc32c (>=0.0.0 && <0.1), exceptions (>=0.10.4 && <0.11), lens-family-core (>=2.0.0 && <2.1), lens-family-th (>=0.5.1 && <0.6), logging (>=3.0.5 && <3.1), managed (>=1.0.7 && <1.1), mtl (>=2.2.2 && <2.3), network (>=3.1.2 && <3.2), proto-lens (>=0.7.0 && <0.8), proto-lens-runtime (>=0.7.0 && <0.8), text (>=1.2.4 && <1.3) [details]
License Apache-2.0
Author Gabriel Volpe
Category Network
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Uploaded by gvolpe at 2020-09-15T09:49:29Z
Distributions NixOS:0.0.3
Downloads 207 total (15 in the last 30 days)
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Maintainer's Corner

For package maintainers and hackage trustees


Readme for supernova-0.0.3

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CI Status

⚠️ it is still very much under development 🚧 so use it at your own risk ⚠️

A supernova is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion. The original object, called the progenitor, either collapses to a neutron star or black hole, or is completely destroyed. The peak optical luminosity of a supernova can be comparable to that of an entire galaxy before fading over several weeks or months.


Quick Start

The example located in test/Main.hs showcases a consumer & producer running concurrently (needs the async library).

main :: IO ()
main = runPulsar conn $ do
  c <- newConsumer topic sub
  p <- newProducer topic
  liftIO $ program c p

conn :: PulsarConnection
conn = connect defaultConnectData

topic :: Topic
topic = defaultTopic "app"

sub :: Subscription
sub = Subscription Exclusive "test-sub"

program :: Consumer IO -> Producer IO -> IO ()
program Consumer {..} Producer {..} =
  let c = fetch >>= \(Message i m) -> msgDecoder m >> ack i >> c
      p = sleep 3 >> traverse_ send messages >> p
  in  concurrently_ c p

A Message contains a MessageID you need for acking and a payload defined as a lazy ByteString.

Note that we wait a few seconds before publishing a message to make sure the consumer is already subscribed. Otherwise, it might miss some messages.

Run it with the following command:

cabal new-run supernova-tests

By default, it logs to the standard output in DEBUG level. You can change it by suppling LogOptions to the alternative function runPulsar'.

runPulsar' :: LogOptions -> PulsarConnection -> Pulsar a -> IO ()


Since both consumers and producers operate on any MonadIO m, we could leverage some streaming libraries. Here's the same example using streamly.

import           Streamly
import qualified Streamly.Prelude              as S

program :: Consumer IO -> Producer IO -> IO ()
program Consumer {..} Producer {..} =
  let c = fetch >>= \(Message i m) -> msgDecoder m >> ack i >> c
      p = sleep 3 >> traverse_ send messages >> p
  in  S.drain . asyncly . maxThreads 10 $ S.yieldM c <> S.yieldM p


It is recommended to use Cachix to reduce the compilation time.


Or within a Nix shell (run nix-shell at the project's root).

cabal new-build

Generate Hackage tarball

cabal new-sdist

Upload documentation

cabal new-haddock --haddock-for-hackage --enable-doc
cabal upload -d dist-newstyle/supernova-0.0.2-docs.tar.gz --publish