The Clarens Grid-Enabled Web Services Framework is an open source, secure, high-performance
"portal" for ubiquitous access to data and computational
resources provided by computing grids.
Clarens was developed as part of a wide-area network Grid-enabled Analysis
Environment for collaborative analysis of data generated by the Compact Muon Solenoid (CMS)
detector at the European Organization for Nuclear Research, CERN.
The server-side application environment provides a standard, easy to use
framework for developing Grid services, with mechanisms for PKI-based
authentication, authorization based on access control lists in the context of
distributed virtual organizations.
Services are automatically published for discovery using a global service
registry, and can be used from a variety of clients, including web browsers, scripts
and full-scale applications.
A computational grid is a hardware and software infrastructure that
provides dependable, consistent, pervasive, and inexpensive access to
high-end computational capabilities.
Kesselman, Foster, The Grid: Blueprint for a new Computing
Infrastructure, 1998. As quoted by Foster,
A more detailed description of individual services and interfaces can be
- File system access (download, directory listings, read/write with
fine-grained access control).
- The ubiquitous echo service for testing and overhead/ping time
- Proxy escrow service, similar to MyProxy.
- VO management
- Job submission.
- Virtual data catalog access
- Metadata catalog access
- Service registration and discovery
- Session logging
- Configuration management
Client server communication
Communication between the client and server is conducted via the
XML-RPC remote precedure call
mechanism, JSON-RPC, and SOAP (only in JClarens). All serialization formats are supported by the same
The server is implemented using Python
within the mod_python framework for the
Apache web server.
There are currently a few clients that are evolving along with the server:
- A Python command-line client
- A compiled module for the ROOT
Most US Grid CAs are supported by this demo installation.
See the screenshots page for a look at
the Root client.
- The Clarens server and Root clients was used by two different groups for
demonstrating remote analysis of Physics data at the Supercomputing 2002 conference.
- The above demo was repeated for Supercomputing 2003, but with a focus
on disk-to-disk file transfer as part of the bandwidth challenge. A transfer
rate of 400MB/s using two Clarens servers and two clients was achieved.
On a desktop 2.6 GHz P4 running the Fedora Core OS, call latency, including
fine grained access control, is 1.4 ms (around 700 calls/s).
On a dual Xeon 3.0 GHz over a LAN performance is around 1450 calls/s.
Moreover, this performance is mainatained at a constant level for large
numbers of users (tested for up to 70 simultaneous users).
The project is hosted by SourceForge, with an extensive summary page.
We are transitioning to using the monotone distributed version
control system to store Clarens source code. The main repository can be
The repository currently contains the Apache web server code, the web
interface, the Clarens web pages, as well as the (in-progress) standalone
The SourceForge CVS pages can still be browsed at
Subscribe to the Clarens mailing list clarens-general.
The list is also archived.
July 23, 2007
Complete overhaul of OpenPkg infrastructure, and new
clarens-server-0.7.6-2 package. See
installation instructions or more
Aug 8, 2006
New version 0.7.3-2 of clarens-server packages to fix a
configuration issue. Use clump update upgrade. New installations
will receive this update by default.
May 24, 2006
New version 0.7.3 of clarens-server and clarens-server-web
Apr 11, 2006
Monotone server updated to 0.26, see the
GAE Wiki page for more information.
Oct 24, 2005
[UPDATED] Released clarens-server-0.7.2.1, and
see the clarens-server-web-0.7.2.
See the list of
Tagged as RELEASE_0_7_2 in monotone.
Jul 13, 2005
Released clarens-server-0.7.1, and
clarens-server-web-0.7.1. See the list of
Tagged as RELEASE_0_7_1 in CVS.
Jul 8, 2005
- Added link to the novel JobMon project that allows web service access and
monitoring to jobs running on worker nodes, even behind firewalls. See more
- Updated the manual to include a chapter
on web client development.
June 29, 2005
Created online documentation for the stand-alone Python client, available
May 2, 2005
Released clarens-server-0.7.0 with changes in preparation for the
service. See the list of changes here.
Tagged as RELEASE_0_7_0 in CVS.
Feb 4, 2005
Released clarens-server-0.6.9 with many
Tagged as RELEASE_0_6_9 in CVS.
Dec 11, 2004
Stand-alone Python client released.
here. Or see the short release notes.