An Open Source Atom Implementation

Atom 1.0 Logo

The goal of the Apache Abdera project is to build a functionally-complete, high-performance implementation of the IETF Atom Syndication Format (RFC 4287) and Atom Publishing Protocol (RFC 5023) specifications.


December 21, 2012: Abdera 1.1.3 Released
Abdera 1.1.3 has been released, containing bug fixes:
  • ABDERA-311: fails to build with java 7
  • ABDERA-309: Allow underscores in URLs
  • ABDERA-293: Abdera-core should support the import the javax* package from JRE
  • ABDERA-285: javamail.dir is not valid, updated directory in description
  • ABDERA-284: Deprecated Axiom interface is used in FOMParser
  • ABDERA-282: Maven build problem
  • ABDERA-281: NoClassDefFoundError in abdera-parser caused by missing axiom-api.jar
  • ABDERA-279: Faulty classloading - unreachable code
  • ABDERA-259: NullPointerException happens when trying to decode HEAD response
  • Axiom dependency updated to version 1.2.14; internal refactorings regarding this dependency
A more detailed list of commits and changes can be found here: CHANGES
January 15, 2011: Abdera 1.1.2 Released
Abdera 1.1.2 has been released, containing performance enhancements and bug fixes:
  • ABDERA-278: Relax the version requirement for commons-codec in OSGi manifests
  • ABDERA-277: Excessive calls to flush() on the Writer responsible for writing JSONStream data
  • ABDERA-251: Charset issue in FOMDiv.getInternalValue() leads to corrupt return value on non-ASCII platforms
  • ABDERA-243: Extra characters generated for entities in XHTML
  • ABDERA-275: Error in Turkish Locale when using GZIP compression
  • ABDERA-258: Abdera needs to support IPv6
  • removed outdated couchdb adapter to get rid of additional maven repo
  • fixed potential null pointers in JSON extension
December 11, 2010: Abdera 1.1.1 Released
Abdera 1.1.1 has been released, containing performance enhancements and bug fixes:
  • ABDERA-262: EntryRequestProcessor and MediaRequestProcessor do not support POST
  • ABDERA-270: OSGi meta-data is broken
  • ABDERA-267: Major performance issue with Abdera (underlying Axiom) object model while writing Atom DOM to XmlStreamWriter
July 10, 2010: Abdera 1.1 Released
Abdera 1.1 has been released, containing many bug fixes.
May 2, 2010: Abdera 1.0 Released
The 1.0 release of Abdera created in January 2009 has now been published.
November 25, 2008: Abdera graduates from the Apache Incubator
The ASF Board of Directors has voted to make Abdera a new top level Apache project. As a result we are now in the process of moving Abdera out of the incubator and into its new location at
April 11, 2008: Abdera 0.4.0 (Incubating) Released
  • A simplified server side framework and API for implementing services.
  • Server side filter API for intercepting requests and implementing concerns such as security.
  • A collection of pre-bundled Atom Publishing Protocol adapters for JDBC, JCR, filesystems, and CouchDB.
  • An improved JSON serialization mechanism.
  • New extensions such as OAuth support.
  • New StreamWriter interface for fast Atom document serialization
  • Improved Unicode performance for IRI implementation
  • URI Template Support
  • HTML Parser
  • Many API improvements and bug fixes!
October 5, 2007: Abdera 0.3.0 (Incubating) Released
  • Support for the Atompub final draft
  • Refactored and simplified Server framework
  • Refactored and simplified AbderaClient
  • ExtensionFactory can now provide the mime type for extension elements
  • Improved extensibility
  • Updated dependencies
  • XPath support improvements
  • Geotagging extensions
  • Simple Sharing extensions
  • WSSE Authentication
  • Bidi extensions (experimental)
  • Atompub features extensions (experimental)
  • Feed paging extensions
  • Feed license extensions
  • XML Encryption with Diffie-Hellman key exchange
  • Spring integration support
  • Extensions now packaged in separate jars for modular distribution
  • Improved error handling
  • More examples
  • Less bugs
  • Lots of other improvements
February 19th, 2007: Abdera 0.2.2 (Incubating) Released
  • Fix the XHTML/XML entry content bug
  • Fix StAX API conformance bugs
  • Update to Apache Axiom 1.2.1
  • Various API Cleanups
December 5th, 2006: Abdera 0.2.0 (Incubating) Released
Features and Fixes:
  • A reworked API that improves usability
  • Decoupled extensions from the underlying parser implementation
  • A Atom Publishing Protocol client implementation
  • Updated support for the current Atom Publishing Protocol draft specification
  • Added support for Internationalized Resource Identifiers (IRIs)
  • Improved Thread Safety
  • Fixed a number of Classloader issues that kept Abdera from working properly in application server environments.
  • Improved Javadocs
  • Added test cases and sample code
  • Added experimental Bidirectional Text support
  • Improved implementation of OpenSearch v1.0 and v1.1 extensions
  • Implementation of MediaRSS extensions
  • Implementation of Feed Paging and Archiving extensions
  • GoogleLogin Authentication Support
June 6th, 2006: Abdera Project proposal accepted for incubation
The Apache Incubator PMC approved the Abdera project proposal.


Abdera 1.1.3
Description Location MD5 Checksum
Abdera 1.1.3 apache-abdera-1.1.3-bin.tar.gz df33b3318a2dee8897fbdf5328839966 (Signature) 23fdd14d80efccc20c9b5131488e39d9 (Signature)
Abdera 1.1.3 Source apache-abdera-1.1.3-src.tar.gz eb6545122a444412e3b3bcaf3471e7e0 (Signature) 0b5f2c334916c289f06c03f8577a9879 (Signature)
Release signing key

Abdera 1.1.2
Description Location MD5 Checksum
Abdera 1.1.2 apache-abdera-1.1.2.tar.gz ee98a356b96a685ea5cf7e039d87e63c (Signature) b8f4a4a8a8b0a843edf29293d6bc828c (Signature)
Abdera 1.1.2 Source apache-abdera-1.1.2-src.tar.gz 25f8e550d0510165e547c606a18996b0 (Signature) 6b21ead3c69156109e050ce467dfe607 (Signature)
Release signing key

Abdera 1.1.1
Description Location MD5 Checksum
Abdera 1.1.1 apache-abdera-1.1.1.tar.gz d8cf56a56d75821a29d4dd13cd581234 (Signature) 17d53cce8fb7a6b66f4f1af5849bfcb6 (Signature)
Abdera 1.1.1 Source apache-abdera-1.1.1-src.tar.gz dbc0949f2f236e79421f38568685ddbf (Signature) 8c145cb620960665b2296a267af5c1c1 (Signature)
Release signing key

Abdera 1.1
Description Location MD5 Checksum
Abdera 1.1 apache-abdera-1.1.tar.gz c713fa3aaa586610b089bdf064ab5512 (Signature) 784e9ed91fd3162bdfdf72f205a68b8a (Signature)
Abdera 1.1 Source apache-abdera-1.1-src.tar.gz 0fef3dfed031be664e089f9cae4a553d (Signature) 01ba162d5ef486924be6d68c71ea5fa1 (Signature)
Release signing key

Abdera 1.0
Description Location MD5 Checksum
Abdera 1.0 apache-abdera-1.0.tar.gz 120644406dbd3693590253b265f61988 (Signature) 095aff705427d6a0c1dfcabecac16334 (Signature)
Abdera 1.0 Source apache-abdera-1.0-src.tar.gz 259d061fe33219693a037c971c05aebe (Signature) fdf0b8da53ac2701f234f4cde437535d (Signature)
Release signing key

Getting Started

The latest source is available in the Subversion repository.

To get started with Abdera you should first familiarize yourself with the Atom Syndication Format and Atom Publishing Protocol specifications and check out the "Getting Started" guide. Sample applications are also available for you to explore.

Take a look at the mailing list archives for answers to questions not covered by the documentation pages. If you need more help or want to discuss Abdera generally, don't hesitate to join the Abdera users mailing list (you can subscribe by sending an empty message to ).

Apache Abdera is an open source project and welcomes all contributions. You can participate by answering questions on the mailing list, filing bug reports for any problems or improvement ideas you come up with or writing documentation and code. See the How the ASF works page for background information on the Apache Software Foundation and the way we work.