On-line object monitoring with new version V4.4 of Go4

For the monitoring of complex experiments often a full data analysis is necessary. This analysis should run continuously on-line. Several visualization and control clients, typically GUIs, should be able to inspect the results from the analysis, mostly histograms, but also other objects like parameters. It should be possible for the clients to get updates of selected data continuously without blocking user actions. The Go4 analysis framework developed at GSI provides this functionality. A Go4 analysis may run in a server mode under control of a non blocking GUI. Analysis and GUI run in separate tasks, optionally on different nodes, communicating through asynchronous multi-threaded object channels. Additional distributed viewers (GUIs) may connect to the same analysis. The Go4 framework is based on ROOT. DAQ data channels are connected by implementation of data source plug-ins. A Go4 analysis is organized in modular steps, which can be set up from the controlling GUI. Parameters can be modified interactively on the fly allowing to steer a running analysis. Analysis objects can be stored and are retrieved after restart. The GUI is implemented in native Qt4 embedding full ROOT graphics. User written GUIs can be attached. Using the Qt de signer the development is very efficient. The GUIs have access to all objects of the analysis like histograms, parameter objects or events. Visual elements may be updated from the analysis asynchronously. Selected objects can be stored to ROOT files. Besides the analysis folders the GUI can browse any number of ROOT files simultaneously. ROOT macros can be executed in the analysis or GUI context, respectively. Complex fits can be performed interactively by a powerful fit package. Go4 v4 runs on Linux, Solaris, Windows (XP, W7) and MacOS. Cross platform connections between G04 environments are possible. Go4 runs in production since several years mainly in the nuclear and atomic physics fields.