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From Apache Wiki <>
Subject [Incubator Wiki] Update of "AccumuloProposal" by BillieRinaldi
Date Fri, 02 Sep 2011 15:21:48 GMT
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The "AccumuloProposal" page has been changed by BillieRinaldi:

create initial Accumulo proposal

New page:
= 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 or that they will not see
an incentive in adopting Accumulo.  There are a few key areas in which Accumulo differs from
HBase.  Some of the desired features of Accumulo could be incorporated into HBase, however
the most important of these may be unlikely to be adopted (see cell-level access labels and
iterators below).  It is a possibility that the codebases will ultimately converge, but the
number of differences at the current time warrants a separate project for Accumulo.

==== 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

==== 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

=== 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. Hadoop, Zookeeper, and 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  Also,
a paper discussing YCSB results for Accumulo will be presented at the 2011 Symposium on Cloud

== 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 [ 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

== Cryptography ==

== Required Resources ==
 * Mailing Lists
   * accumulo-private
   * accumulo-dev
   * accumulo-commits
   * accumulo-user

 * Subversion Directory

 * Issue Tracking
   * JIRA Accumulo (ACCUMULO)

 * Continuous Integration
   * Jenkins builds on

 * Web
   * wiki at or

== 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, ?, ?
 * Sponsoring Entity: Apache Incubator

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