discussion. A few questions were asked, and the proposal was clarified
in response. Sufficient mentors have volunteered. I thus feel we are
now ready for a vote.
The latest proposal can be found at the end of this email and at:
http://wiki.apache.org/incubator/AccumuloProposal
The discussion regarding the proposal can be found at:
Please cast your votes:
[ ] +1 Accept Accumulo for incubation
[ ] +0 Indifferent to Accumulo incubation
[ ] -1 Reject Accumulo for incubation
This vote will close 72 hours from now.
Thanks,
Doug
-----------------------
= Accumulo Proposal =
== Abstract ==
Accumulo is a distributed key/value store that provides expressive,
cell-level access labels.
== Proposal ==
Accumulo is a sorted, distributed key/value store based on Google's
BigTable design. It is built on top of Apache Hadoop, Zookeeper, and
Thrift. It features a few novel improvements on the BigTable design in
the form of cell-level access labels and a server-side programming
mechanism that can modify key/value pairs at various points in the data
management process.
== Background ==
Google published the design of BigTable in 2006. Several other open
source projects have implemented aspects of this design including HBase,
CloudStore, and Cassandra. Accumulo began its development in 2008.
== Rationale ==
There is a need for a flexible, high performance distributed key/value
store that provides expressive, fine-grained access labels. The
communities we expect to be most interested in such a project are
government, health care, and other industries where privacy is a
concern. We have made much progress in developing this project over the
past 3 years and believe both the project and the interested communities
would benefit from this work being openly available and having open
development.
== Current Status ==
=== Meritocracy ===
We intend to strongly encourage the community to help with and
contribute to the code. We will actively seek potential committers and
help them become familiar with the codebase.
=== Community ===
A strong government community has developed around Accumulo and training
classes have been ongoing for about a year. Hundreds of developers use
Accumulo.
=== Core Developers ===
The developers are mainly employed by the National Security Agency, but
we anticipate interest developing among other companies.
=== Alignment ===
Accumulo is built on top of Hadoop, Zookeeper, and Thrift. It builds
with Maven. Due to the strong relationship with these Apache projects,
the incubator is a good match for Accumulo.
== Known Risks ==
=== Orphaned Products ===
There is only a small risk of being orphaned. The community is
committed to improving the codebase of the project due to its fulfilling
needs not addressed by any other software.
=== Inexperience with Open Source ===
The codebase has been treated internally as an open source project since
its beginning, and the initial Apache committers have been involved with
the code for multiple years. While our experience with public open
source is limited, we do not anticipate difficulty in operating under
Apache's development process.
=== Homogeneous Developers ===
The committers have multiple employers and it is expected that
committers from different companies will be recruited.
=== Reliance on Salaried Developers ===
The initial committers are all paid by their employers to work on
Accumulo and we expect such employment to continue. Some of the initial
committers would continue as volunteers even if no longer employed to do so.
=== Relationships with Other Apache Products ===
Accumulo uses Hadoop, Zookeeper, Thrift, Maven, log4j, commons-lang,
-net, -io, -jci, -collections, -configuration, -logging, and -codec.
=== Relationship to HBase ===
Accumulo and HBase are both based on the design of Google's BigTable, so
there is a danger that potential users will have difficulty
distinguishing the two. Some of the key areas in which Accumulo differs
from HBase are discussed below. It may be possible to incorporate the
desired features of Accumulo into HBase. However, the amount of work
required would slow development of HBase and Accumulo considerably. We
believe this warrants a podling for Accumulo at the current time. We
expect active cross-pollination will occur between HBase and podling
Accumulo and it is possible that the codebases and projects will
ultimately converge.
==== Access Labels ====
Accumulo has an additional portion of its key that sorts after the
column qualifier and before the timestamp. It is called column
visibility and enables expressive cell-level access control.
Authorizations are passed with each query to control what data is
returned to the user. The column visibilities are boolean AND and OR
combinations of arbitrary strings (such as "(A&B)|C") and authorizations
are sets of strings (such as {C,D}).
==== Iterators ====
Accumulo has a novel server-side programming mechanism that can modify
the data written to disk or returned to the user. This mechanism can be
configured for any of the scopes where data is read from or written to
disk. It can be used to perform joins on data within a single tablet.
==== Flexibility ====
HBase requires the user to specify the set of column families to be used
up front. Accumulo places no restrictions on the column families.
Also, each column family in HBase is stored separately on disk.
Accumulo allows column families to be grouped together on disk, as does
BigTable. This enables users to configure how their data is stored,
potentially providing improvements in compression and lookup speeds. It
gives Accumulo a row/column hybrid nature, while HBase is currently
column-oriented.
==== Testing ====
Accumulo has testing frameworks that have resulted in its achieving a
high level of correctness and performance. We have observed that under
some configurations and conditions Accumulo will outperform HBase and
provide greater data integrity.
==== Logging ====
HBase uses a write-ahead log on the Hadoop Distributed File System.
Accumulo has its own logging service that does not depend on
communication with the HDFS NameNode.
==== Storage ====
Accumulo has a relative key file format that improves compression.
==== Areas in which HBase features improvements over Accumulo ====
in memory tables, upserts, coprocessors, connections to other projects
such as Cascading and Pig
=== Expectations ===
There is a risk that Accumulo will be criticized for not providing
adequate security. The access labels in Accumulo do not in themselves
provide a complete security solution, but are a mechanism for labeling
each piece of data with the authorizations that are necessary to see it.
=== Apache Brand ===
Our interest in releasing this code as an Apache incubator project is
due to its strong relationship with other Apache projects, i.e. Accumulo
has dependencies on Hadoop, Zookeeper, and Thrift and has complementary
goals to HBase.
== Documentation ==
There is not currently documentation about Accumulo on the web, but a
fair amount of documentation and training materials exists and will be
provided on the Accumulo wiki at apache.org. Also, a paper discussing
YCSB results for Accumulo will be presented at the 2011 Symposium on
Cloud Computing.
== Initial Source ==
Accumulo has been in development since spring 2008. There are hundreds
of developers using it and tens of developers have contributed to it.
The core codebase consists of 200,000 lines of code (mainly Java) and
100s of pages of documentation. There are also a few projects built on
top of Accumulo that may be added to its contrib in the future. These
include support for Hive, Matlab, YCSB, and graph processing.
== Source and Intellectual Property Submission Plan ==
Accumulo core code, examples, documention, and training materials will
be submitted by the National Security Agency.
We will also be soliciting contributions of further plugins from MIT
Lincoln Labs, Carnegie Mellon University, and others.
Accumulo has been developed by a mix of government employees and private
companies under government contract. Material developed by government
employees is in the public domain and no U.S. copyright exists in works
of the federal government. For the contractor developed material in the
initial submission, the U.S. Government has sufficient authority per the
ICLA from the copyright owner to contribute the Accumulo code to the
incubator.
There has been some discussion regarding accepting contributions from US
Government sources on https://issues.apache.org/jira/browse/LEGAL-93. We
propose that the NSA will sign an ICLA/CCLA if that document could be
slightly modified to explicitly address copyright in works of government
employees. Specifically, we propose that the definition of "You" be
modified to include "the copyright owner, the owner of a Contribution
not subject to copyright, or legal entity authorized by the copyright
owner that is making this Agreement." In addition, section 2, the
copyright license grant be modified after "You hereby grant" that either
states "to the extent authorized by law" or "to the extent copyright
exists in the Contribution." These changes will permit US Government
employee developed work to be included.
One proposed solution is to form a Collaborative Research and
Development Agreement (CRADA) between the Apache Software Foundation and
the US Government, but this will not solve the underlying problem that
U.S. law does not grant copyright to works of government employees. At
this time a CRADA is not necessary but should it be determined that a
CRADA is necessary, we would like to work through that process during
the incubation phase of Accumulo rather than before acceptance as this
may take time to enter into an agreement.
== External Dependencies ==
jetty (Apache and EPL), jline (BSD), jfreechart (LGPL), jcommon (LGPL),
slf4j (MIT), junit (CPL)
== Cryptography ==
none
== Required Resources ==
* Mailing Lists
* accumulo-private
* accumulo-dev
* accumulo-commits
* accumulo-user
* Subversion Directory
* https://svn.apache.org/repos/asf/incubator/accumulo
* Issue Tracking
* JIRA Accumulo (ACCUMULO)
* Continuous Integration
* Jenkins builds on https://builds.apache.org/
* Web
* http://incubator.apache.org/accumulo/
* wiki at http://wiki.apache.org or http://cwiki.apache.org
== Initial Committers ==
* Aaron Cordova (aaron at cordovas dot org)
* Adam Fuchs (adam.p.fuchs at ugov dot gov)
* Eric Newton (ecn at swcomplete dot com)
* Billie Rinaldi (billie.j.rinaldi at ugov dot gov)
* Keith Turner (keith.turner at ptech-llc dot com)
* John Vines (john.w.vines at ugov dot gov)
* Chris Waring (christopher.a.waring at ugov dot gov)
== Affiliations ==
* Aaron Cordova, The Interllective
* Adam Fuchs, National Security Agency
* Eric Newton, SW Complete Incorporated
* Billie Rinaldi, National Security Agency
* Keith Turner, Peterson Technology LLC
* John Vines, National Security Agency
* Chris Waring, National Security Agency
== Sponsors ==
* Champion: Doug Cutting
== Nominated Mentors ==
* Benson Margulies
* Alan Cabrera
* Bernd Fondermann
* Owen O'Malley
== Sponsoring Entity ==
* Apache Incubator
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