incubator-general mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Bill Graham <>
Subject [PROPOSAL] Heron
Date Thu, 08 Jun 2017 17:23:20 GMT
Dear Apache Incubator Community,

We are excited to share our proposal for discussion and feedback
for entering Apache Incubation. Heron is a real-time, distributed,
fault-tolerant stream processing engine.

Our proposal can be found at
 and is included below.

Thank you,

Bill Graham on behalf of the Heron developers

# Heron Proposal

## Abstract
Heron is a real-time, distributed, fault-tolerant stream processing engine
initially developed by Twitter.

## Proposal

Heron is a real-time stream processing engine built for high performance,
ease of manageability, performance predictability and developer
productivity[1]. We wish to develop a community around Heron to increase
contributions and see Heron thrive in an open forum.

## Background

Heron provides the ability for developers to compose directed acyclic
graphs (DAGs) of real-time query execution logic (i.e. a topology) and
submit the topology to execute on a pluggable job scheduling system (e.g.,
Apache Aurora, YARN, Marathon, etc). Users can employ either the native
Heron API or the Apache Storm API to develop the topology. Heron supports
the Storm API for ease of migration, but beyond that Heron’s architecture
differs considerably from Storm’s.

Users submit a topology to the scheduler using the Heron client, which uses
the Heron binary libraries to deploy all daemons required to run and manage
the topology. The topology therefore has no reliance on centrally managed
Heron services, only on a generic job scheduling system, which lends itself
well to be run on top of Apache Aurora/Mesos or Apache Hadoop/YARN (among

The scheduler runs each topology as a job consisting of multiple
containers. One of the containers runs the topology master, responsible for
managing the topology. The remaining containers each runs a stream manager
responsible for data routing, a metrics manager that collects and reports
various metrics and a number of processes called Heron instances which run
the user-defined logic on the stream of tuples. Parallelism is achieved via
process-based isolation of Heron instances, which provides predictable
performance while simplifying debugging. The containers are allocated and
managed by the scheduler framework based on resource availability of nodes
in the cluster. The metadata for the topology, such as the physical plan
and execution details, are stored in the pluggable Heron State Manager
(e.g. Apache ZooKeeper).

## Rationale

Heron is a general-purpose, modular and extensible platform that can be
leveraged to support common, real-time analytics use cases. There is an
increasing demand for open-source, scalable real-time analytics systems. We
believe that Heron can be leveraged by other organizations to build
streaming applications that can benefit from its robustness, high
performance, adaptability to cloud environments and ease of use. Moreover,
we hope that open-sourcing Heron will help to further evolve the technology
as the project attracts contributors with diverse backgrounds and areas of

We believe the Apache foundation is a great fit as the long-term home for
Heron, as it provides an established process for community-driven
development and decision making by consensus. This is exactly the model we
want for future Heron development.

## Initial Goals

* Move the existing codebase, website, documentation, and mailing lists to
Apache-hosted infrastructure.
* Integrate with the Apache development process.
* Ensure all dependencies are compliant with Apache License version 2.0.
* Incrementally develop and release per Apache guidelines.

## Current Status

Heron is a stable project used in production at Twitter since 2014 and open
sourced under the ASL v2 license in 2016. The Heron source code is
currently hosted at (, which
will seed the Apache git repository.

### Meritocracy

By submitting this incubator proposal, we’re expressing our intent to build
a diverse developer community around Heron that will conduct itself
according to The Apache Way and use a meritocratic means of building it's
committer base. Several companies and universities have already expressed
interest in and contributed to Heron. Our goal is to grow the Heron
community by encouraging open communication, contribution and participation
of all types, and ensuring that contributors are recognized appropriately.

### Community

Heron is currently being used by Twitter, Google, Machine Zone and and has received significant contributions by Microsoft and
Streamlio. By bringing Heron into the Apache ecosystem, we believe we can
attract even more developers who are interested in creating real-time
systems to build the project's contributor base.

### Core Developers

Current core developers are engineers from Twitter, Google, Microsoft and

### Alignment

Heron utilizes a number of Apache technologies. Heron leverages Apache
ZooKeeper for coordination and has scheduler implementations to integrate
with Apache Mesos, Apache Aurora and Apache Hadoop's YARN (via Apache REEF)
as well as spout implementations to integrate with Apache Kafka and metrics
implementations to integrate with Scribe. Heron also implements the Apache
Storm user-level API, which allows topologies written against Storm to run
in Heron. We believe that having Heron at Apache will help further the
growth of the streaming compute community, as well as encourage cooperation
and developer cross pollination with other Apache projects.

## Known Risks

### Orphaned Products

The risk of the Heron project being abandoned is minimal. It is used in
production at Twitter and Google and other companies are evaluating or
adopting it for production use.

### Inexperience with Open Source

All of the core contributors to the project have considerable experience
with open source software development. Bill Graham[2], Ashvin Agrawal[3]
and Supun Kamburugamuve[4], committers on the project, are PMCs on other
Apache projects and Bill and Ashvin have gone through the Apache incubator
process. Twitter has already donated numerous projects to the ASF (e.g.,
Apache Mesos, Apache Aurora, Apache Parquet). We also plan to be mentored
by experienced ASF members that can help with any roadblocks.

### Homogenous Developers

Initial committers come from 5 separate organizations. Our intention is
increase the diversity of contributing developers and their affiliations.
To date github contributions have come from approximately 50 contributors
from outside the Twitter team.

### Reliance on Salaried Developers

It is expected that Heron development will occur on both salaried time and
on volunteer time. The majority of initial committers are paid by their
employers to contribute to this project. We are committed to recruiting
additional committers from other organizations as well as non-salaried
committers to join project.

### Relationships with Other Apache Products

As mentioned in the Alignment section, Heron implements the Apache Storm
API and integrates with multiple Apache schedulers (Apache Mesos, Apache
Aurora and Apache Hadoop's YARN) as well as Apache ZooKeeper and Apache

### An Excessive Fascination with the Apache Brand

Heron's popularity is growing in the streaming compute space and we are
long time supporters of the Apache brand. This proposal is not for the
purpose of generating publicity through. Rather, the primary benefits to
joining Apache are those of community building and open decision making
outlined in the Rationale section.

## Documentation

This proposal exists online as
incubator/HeronProposal. Extensive documentation can be found on github at and the source code is well documented.

## Source and Intellectual Property Submission Plan

The Heron codebase is currently hosted on Github: During incubation, the codebase will be
migrated to Apache infrastructure. The source code is already ASF 2.0

## External Dependencies

All external libraries have ASF 2.0 compatible licenses except for pylint.
The pylint library is GPL licensed, but is only used for pre-build Python
style checks and is neither bundled with, nor relied upon by, the Heron
source or binary release artifacts.

## Cryptography

Heron does not use any cryptography libraries.

## Required Resources

### Mailing lists (with moderated subscriptions)

## Subversion Directory

Git is the preferred source control system: git://

## Issue Tracking


## Initial Committers

* Andrew Jorgensen (andrew at andrewjorgensen dot com)
* Ashvin Agrawal (ashvin at apache dot org)*
* Avrilia Floratou (avrilia dot floratou at gmail dot com)
* Bill Graham (billgraham at apache dot org)*
* Brian Hatfield (bmhatfield at gmail dot com)
* Chris Kellogg (cckellogg at gmail dot com)
* Huijun Wu (huijun dot wu dot 2010 at gmail dot com)
* Karthik Ramasamy (karthik at gmail dot com)
* Maosong Fu (maosongfu at gmail dot com)
* Neng Lu(freeneng at gmail dot com)
* Runhang Li (obj dot runhang at gmail dot com)
* Sanjeev Kulkarni (sanjeevrk at gmail dot com)
* Supun Kamburugamuve (supun at apache dot org)*
* Thomas Sun (tom dot ssf at gmail dot com)
* Yaliang Wang (yaliang dot w dot wang at ieee dot org)

## Affiliations

* Andrew Jorgensen (Google)
* Ashvin Agrawal (Microsoft)
* Avrilia Floratou (Microsoft)
* Bill Graham (Twitter)
* Brian Hatfield (Google)
* Chris Kellogg (Twitter)
* Huijun Wu (Twitter)
* Karthik Ramasamy (Streamlio)
* Maosong Fu (Twitter)
* Neng Lu (Twitter)
* Runhang Li (Twitter)
* Sanjeev Kulkarni (Streamlio)
* Supun Kamburugamuve (Indiana University)
* Thomas Sun (Twitter)
* Yaliang Wang (Twitter)

## Sponsors

### Champion

* Julien Le Dem (julien at apache dot org)

### Nominated Mentors

* Jake Farrell (jfarrell at apache dot org)
* Jacques Nadeau (jacques at apache dot org)
* Julien Le Dem (julien at apache dot org)

### Sponsoring Entity

The Apache Incubator

### Footnotes

1 - Papers detailing Heron are available at
cfm?id=2742788 and
2 -
3 -
4 -

  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message