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We update our CHEP06 presentation on the ATLAS experiment software infrastructure used to build, validate, distribute, and document the ATLAS offline software. The ATLAS collaboration's computational resources and software developers are distributed around the globe in more then 30 counties. The ATLAS offline code base is currently over 5 MSLOC in 10000+ C++ classes organized into about 1700 packages. More than 600 developers contribute code. Since our last report, we have developed a powerful, flexible system to request code versions to be included in software builds, made changes to our software building tools, created a system of nightly builds to validate significant code changes, improved the tools for distributing the code to our computational sites around, and made many advancements in our tools to document our code.

We present an event display for the ATLAS Experiment, called Virtual Point 1 (VP1), designed initially for deployment at point 1 of the LHC, the location of the ATLAS detector. The Qt/OpenGL based application provides truthful and interactive 3D representations of both event and non-event data, and now serves a general-purpose role within the experiment. Thus, VP1 is used both online (in the control room itself or remotely via a special "live" mode) and offline environments to provide fast debugging and understanding of events, detector status and software. In addition to a flexible plugin infrastructure and a high level of configurability, this multi-purpose role is mainly facilitated by the application being embedded directly in the ATLAS offline software framework, enabling it to use the native Event Data Model directly, and thus run on any source of ATLAS data, or even directly from within e.g. reconstruction jobs. Finally, VP1 provides high-quality pictures and movies, useful for outreach purposes.

We describe an event visualization package in use in ATLAS. The package is based upon Open Inventor and its HEPVIs extensions. It is integrated into ATLAS's analysis framework, is modular and open to user extensions, co-displays the real detector description/simulation (GeoModel/GEANT) geometry together with event data, and renders in real time on regular laptop computers, using their available graphics acceleration. The functionality requires no commercial software. It has been used to debug, extensively, the geometry of the ATLAS detector and is now being applied to commissioning activities.

The event data model (EDM) of the ATLAS experiment is presented. For large collaborations like the ATLAS experiment common interfaces and data objects are a necessity to insure easy maintenance and coherence of the experiments software platform over a long period of time. The ATLAS EDM improves commonality across the detector subsystems and subgroups such as trigger, test beam reconstruction, combined event reconstruction, and physics analysis. Furthermore the EDM allows the use of common software between online data processing and offline reconstruction. One important task of the EDM group is to provide know-how and the infrastructure to secure the accessibility of data even after changes to the data model. New processes have been put into place to manage the decoupling of the persistent (on disk) storage and the transient (in memory), and how to handle requests from developers to change or add to the stored data model.

The event data model (EDM) of the ATLAS experiment is presented. For large collaborations like the ATLAS experiment common interfaces and data objects are a necessity to insure easy maintenance and coherence of the experiments software platform over a long period of time. The ATLAS EDM improves commonality across the detector subsystems and subgroups such as trigger, test beam reconstruction, combined event reconstruction, and physics analysis. The object oriented approach in the description of the detector data allows the possibility to have one common raw data flow. Furthermore the EDM allows the use of common software between online data processing and offline reconstruction. One important component of the ATLAS EDM is a common track class which is used for combined track reconstruction across the innermost tracking subdetectors and is also used for tracking in the muon detectors. The structure of the track object and the variety of track parameters are presented. For the combined event reconstruction a common particle class is introduced which serves as the interface between event reconstruction and physics analysis.