The Use of HepRep in GLAST

TL;DR

The paper discusses how the GLAST experiment implemented HepRep, a flexible graphics description format, to support multiple client applications and integrate with their event display infrastructure for gamma-ray telescope data visualization.

Contribution

It presents a HepRep integration architecture for GLAST that abstracts XML and CORBA details, enabling flexible, extensible event display support across different client applications.

Findings

HepRep was successfully integrated into GLAST's infrastructure.

GLAST's architecture supports multiple client applications like WIRED and FRED.

The system allows easy export and publication of event data in XML and CORBA formats.

Abstract

HepRep is a generic, hierarchical format for description of graphics representables that can be augmented by physics information and relational properties. It was developed for high energy physics event display applications and is especially suited to client/server or component frameworks. The GLAST experiment, an international effort led by NASA for a gamma-ray telescope to launch in 2006, chose HepRep to provide a flexible, extensible and maintainable framework for their event display without tying their users to any one graphics application. To support HepRep in their GUADI infrastructure, GLAST developed a HepRep filler and builder architecture. The architecture hides the details of XML and CORBA in a set of base and helper classes allowing physics experts to focus on what data they want to represent. GLAST has two GAUDI services: HepRepSvc, which registers HepRep fillers in a global registry and allows the HepRep to be exported to XML, and CorbaSvc, which allows the HepRep to be published through a CORBA interface and which allows the client application to feed commands back to GAUDI (such as start next event, or run some GAUDI algorithm). GLAST's HepRep solution gives users a choice of client applications, WIRED (written in Java) or FRED (written in C++ and Ruby), and leaves them free to move to any future HepRep-compliant event display.