Use of ROOT in the

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Use of ROOT in the D0 OnlineEvent Monitoring
System
Joel Snow, D0 Collaboration, February 2000
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D0 OnlineEvent Monitoring System

• Three Major Components
• Data Acquisition System
• Monitoring Executables
• Graphical User Interface

• Three Operating Systems
• Software Portability

Joel Snow, D0 Collaboration, February 2000
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ROOT Framework

• Provides
• Portability
• Physics analysis tools
• Shared memory
• Network sockets
• Graphical widgets

ROOT is an attractive choice for online
monitoring applications
Joel Snow, D0 Collaboration, February 2000
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Data Acquisition System

• Front-end electronics
• Two levels of hardware triggers
• Software trigger
• Data transfer system

Joel Snow, D0 Collaboration, February 2000
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D0 Run II Online Event Monitoring Architecture
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D0 Online Event Monitoring Physical Data Flow
L3 Filter Node
L3 Filter Node
100 Mbit Ethernet
Gbit Ethernet
L3 Filter Node
L3 Filter Node
100 Mb Switch
100 Mb Switch
Collector / Router
Collector / Router
100 Mb Switch
To FCC
Gb Switch
Data Logger
Data Logger
EXAMINE
Data Distributor
Buffer Disk
Buffer Disk
EXAMINE
RIP Interface
RIP Interface
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D0 Online Event Monitoring Logical Data Flow
L3 Filter Node
L3 Filter Node
No Flow Control
L3 Filter Node
L3 Filter Node
Collector / Router
Collector / Router
Routing based on Stream ID
Data Distributor
Data Logger
Data Logger
EXAMINE
Distribution based on Trigger type
Buffer Disk
Buffer Disk
EXAMINE
RIP Interface
RIP Interface
To FCC
To FCC
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Monitoring Executables(Examines)

• Detector performance
• Physics Objects - e's m's jets

• Unpack raw data
• Reconstruct events
• Fill Histograms
• Provide event displays

• Multiple Examines run on Linux PC's

• Event selection via RCP file
• Connect to DD with ACE
• Apply algorithms to data
• Interact with user interface

Joel Snow, D0 Collaboration, February 2000
9
D0 Online Event Monitoring Processing Data and
Message Flow
Request Message
DD Host
Control Message
Data Flow
DD
Register
Commentary
Event Buffer Assigned at the Requests
Monitoring PC-Nodes
Offline Framework Flow
Initialize
Process Events
Finish
ReadEventDaq
Repeat
Initiate separate threads
Histogram Port.
Message Interface
Spawn an Examine Executable
Histogram Interface
. . .
EvtDSP Interface
Watchdogs for thread protection are separate
Process Registry
Start Processing
Pause/ Resume
EoR Query
Stop
Select Examine
(Event display and other offline fwrk functions
not added)
Abort
Status
Select Input
GUI Process Control Nodes
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D0 Online Event Monitoring Histogram Control Flow
Request Message
DD Host
Control Message
Data Flow
DD
Event Buffer Assigned at the Requests
Register
Commentary
Monitoring PC-Nodes
Initialize
Process Events
ReadEvent Daq
Finish
Histogram Port
Repeat
Initiate a thread
Histogram Interface
Process Registry
Reset
Input Select
Save
Display
Compare
Update
Print
ROOT
Step Hists.
Cycle Hists
GUI Histogram Control Nodes
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D0 Online Monitoring Interaction Sequence
Examine Main Thread
Process Registry
GetEvt Thread
Other Threads
Initialization Sequence
GUI
D/D
Process Inquiry
Initialize (Start Threads)
Process List
Initialize (Connect to D/D Transfer Selections)
Start Examine
Ready(Threads begun)
Start Process
Ready (Connection made buffer assigned)
Initialize (Start Thread assign buffer)
Ready (Thread begun and Connected to D/D)
Ready (All threads begun, Port s assigned)
Ready (Examine begun, Port s assigned)
Event Request
Event Requests Processing Events
Event Processing
Event Transfer
Inquiries Process Control (Pause, Resume,
Reset, etc)
Inquiries Process Cntrl.
Inquiries Action
Reports
Status Action Reports (Pause, Resume, Reset,
etc)
End of Run Signal
End of Run Signal
End of Process Inquiry
Termination Sequence
Finish Clean up
Terminate
Terminate Up
End of Process Request
Terminated
Terminated
Terminated
Terminated
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Graphical User Interface

• Control remote Examine
• Obtain info from Examine
• histograms
• status/alarms

• Checks process registry
• Attach to existing Examine
• No control functions, observer mode
• Many may attach to single Examine
• Start new Examine
• Full control functions, creator mode

Joel Snow, D0 Collaboration, February 2000
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GUI Functions

• Histogram
• Display
• Step
• Compare
• Update
• Reset
• Cycle
• Save
• Print

• Control
• Start/Stop
• Pause/Resume
• Abort
• Status
• Dump Event
• Display Event

Joel Snow, D0 Collaboration, February 2000
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D0 Event Monitoring Process Control!!
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Process Control
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D0 ROOT GUI Histogram Control
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Histogram Display
A ROOT Histogram Window
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Cycling Histograms
A ROOT Histogram Window
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ROOT's Use

• Main analysis tool for Examines
• Results in ROOT object format
• TFile, THxx, TNtuple
• Examine - GUI communication
• TSocket, TServerSocket, TMessage
• Synchronous - control histograms
• Asynchronous - alarms messages
• Idle loop accessed by inheriting from
  TApplication
• GUI built from widget classes
• TGxxxx classes, TVirtualX

Joel Snow, D0 Collaboration, February 2000
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Conclusion

• D0 online event monitoring system (D0OEMS) uses
  an asynchronous framework to reconstruct events,
  calulate physical quantities, and fill histograms
• User interacts with framework through a GUI which
  provides information and control functionalities
• Features of the ROOT framework have been
  successfully integrated into D0OEMS
• While data taking is a year away, detector
  component commissioning is in progress. The
  D0OEMS described here is being used to verify the
  component performances
• User response will guide future improvements
• Hope to provide web based access of information
  to remote collaborators

Joel Snow, D0 Collaboration, February 2000