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From Apache Wiki <>
Subject [Incubator Wiki] Update of "S2GraphProposal" by DoyungYoon
Date Mon, 02 Nov 2015 02:01:29 GMT
Dear Wiki user,

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The "S2GraphProposal" page has been changed by DoyungYoon:

New page:
= S2Graph Proposal =

== Abstract ==
S2Graph is a distributed and scalable OLTP graph database built on HBase to support fast traversal
on extremely large graph.

== Proposal ==
S2Graph is to provide a scalable distributed graph database engine over key/value storage
such as HBase. S2Graph provide fully ashynchronous API to manupulate data as property graph
model and fast breadth first search query on graph. 

== Background ==
S2Graph initially started as an internal project at to efficiently store user relation
and user activities as one large graph and provide unified query to traverse graph. It was
open sourced on Github about a 3 months ago in June 2015.

Over time S2Graph, together with HBase as storage tier, has begun to be adapted into various
applications, such as messaging, social feeds, realtime recommendations at Kakao. 

Users can benefit from S2Graph`s generalized high level API instead of low-level key/value
API for graph abstraction, just like Phoenix provide SQL layer over HBase. 

== Rationale ==
Graph data(highly interconnected data) is very abundant and important these days.
When user have a multitude of relationships, each with complex properties associated with
them, graph model is more intuitive and efficient than tabular format(RDBMS). 
There are many ASF projects that provide SQL layer, but there is no ASF projects that provide
scalable graph layer on existing hadoop echo system.
When graph data grows to trillion edge scale, the process of traversing takes a long time
and costly. However, with the benefit of HBase`s scalable architecture, S2Graph can traverse
large graph in breadth first search manner efficiently.

S2Graph also interoperates with several existing Apache projects(HBase, Spark) to provide
way to merge real time events and batch processed data using property graph data model. 

Many developers are running their own domain specific API servers to serve their data products,
but graph model is general and S2Graph API fully support traverse on graph, so it can be used
as scalable general purpose API serving layer for various domains. 
As long as data can be modeled as graph, then users can avoid tedious work for developing
customized API servers by using S2Graph.

== Initial Goals ==
The initial goals will be to move the existing codebase to Apache and integrate with the Apache
development process. Once this is accomplished, we plan for incremental development and releases
that follow the Apache guidelines.

== Current Status ==

=== Meritocracy ===
S2Graph operated on meritocratic principles from the get go. Currently, all the discussions
pertaining to S2Graph development are public on Github. The current incubation 
proposal includes the major code contributors to S2Graph. Several additional people have worked
on the S2graph codebase for industry use cases and would be interested in becoming committers.
We are starting with a small committer group and we plan to add additional committers following
an open merit-based decision process during the incubation phase.    
=== Community ===
We have already begun building a community but at this time the community consists only of
S2Graph developers – all Kakao employees – and prospective users. 
S2Graph seeks to develop developer and user communities during incubation.

=== Core Developers ===
S2Graph is currently being designed and developed by 2 engineers from Kakao. - Doyung Yoon,
Deawon Jeong. 

=== Alignment ===
Our proposed S2Graph effort aligns closely with Apache HBase. The HBase project perimeter
is denoted by a simple byte-array based Create, Read, Update, Delete and Scan APIs with no
current plans to extend beyond this bounds. 

S2Graph complements this with a higher level API for property graph model.

S2Graph was designed to offer scalable distributed graph database skin over HBase from the
beginning in order to provide property graph model and breadth first search, and continue
to focus on providing graph model.

== Known Risks ==
=== Orphaned Products ===
The core developers of S2Graph team plan to work full time on this project. There is very
little risk of S2Graph getting orphaned since at least one large company (Kakao) is extensively
using it in their production HBase clusters. For example, currently there are 20+ use cases
with more than 1+Trillion edges and 140 million breadth first search query requests per minute
using S2Graph in production. 
We plan to extend and diversify this community further through Apache.

=== Inexperience with Open Source ===
The core developers are all active users and followers of open source. They are already committers
and contributors to the S2Graph Github project. All have been involved with the source code
that has been released under an open source license. Though the core set of Developers do
not have Apache Open Source experience, there are plans to onboard individuals with Apache
open source experience on to the project.

=== Homogenous Developers ===
Most committers in this proposal belong to the same institution (Kakao). The engagement of
these committers goes well beyond the necessary development to support research, and all committers
work on S2Graph full time. 
Several people from other institutions are working on and are familiar with the S2Graph codebase.
We will work to attract them as future committers during the incubation phase, following a
merit-based approach.

=== Reliance on Salaried Developers ===
Kakao invested in S2Graph as the distributed graph database solution on top of HBase and some
of its key engineers are working full time on the project. 
We look forward to other Apache developers and researchers to contribute to the project. 
Also key to addressing the risk associated with relying on Salaried developers from a single
entity is to increase the diversity of the contributors and actively lobby for Domain experts
in the graph database space to contribute. Apache S2Graph intends to do this.

=== Relationships with Other Apache Products ===
S2Graph has a strong relationship and dependency with Apache Hadoop HBase and Spark. 
Being part of Apache’s Incubation community, could help with a closer collaboration among
these two projects and as well as others. 

=== An Excessive Fascination with the Apache Brand ===
S2Graph is proposing to enter incubation at Apache in order to help efforts to diversify the
committer-base, not so much to capitalize on the Apache brand. The S2Graph project is in production
use already inside Kakao, but is not expected to be an Kakao product for external customers.
As such, the S2Graph project is not seeking to use the Apache brand as a marketing tool.

== Documentation ==
Information about S2Graph can be found at The following
links provide more information about S2Graph in open source:
 * S2Graph web site:
 * Codebase at Github:
 * Issue Tracking:
 * User community:!forum/s2graph

== Initial Source ==

The S2Graph codebase is currently hosted on Github:

=== Source and Intellectual Property Submission Plan ===

Currently, the S2Graph codebase is distributed under the Apache 2.0 License.

== External Dependencies ==

Beyond relying on Apache HBase, Phoenix has the following external dependencies:
 * Asynchbase (BSD license:
 * Mysql (BSD license:
 * Play Framework (Apache 2.0 license:
 * Scala (
 * Spark
 * Kafka

== Required Resources ==

=== Mailing list ===

We will migrate our mailing lists to the following:

=== Source control ===

The S2Graph team would like to use Git for source control, due to our current use of Git.
We request a writeable Git repo for S2Graph, and mirroring to be set up to Github through

=== Issue Tracking ===

S2Graph currently uses the github issue tracking system associated with its github repo:
We will migrate to the Apache JIRA:

=== Other Resources ===

Jenkins/Hudson for builds and test running.
Wiki for documentation purposes
Blog to improve project dissemination

== Initial Committers ==

 * Doyung Yoon <shom83 at>
 * Daewon Jeong <blueiur at>
 * Jaesang Kim <honeysleep at>
 * Hwansung Yu <deejayfwan at>
 * Min-Seok Kim < at>
 * Chul Kang <miralchul at>

== Affiliations ==

The initial committers are from one organizations: Kakao.
 * Doyung Yoon, Kakao
 * Daewon Jeong, Kakao
 * Jaesang Kim, Kakao
 * Hwansung Yu, Kakao
 * Min-Seok Kim, Kakao
 * Chul Kang, Kakao

== Sponsors ==

=== Champion ===

=== Nominated Mentors ===

=== Sponsoring Entity ===

 * The Apache Incubator

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