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Contents. Overview Publisher/Subscriber Monitoring Components Shared Memory TCP Exchange Data Format ROOT Interface TPC Readout Structure Decoding Applications. HOMER Overview - Purpose. Access to Publisher/Subscriber data stream Examine data at any stage of P/S processing

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  1. Contents • Overview • Publisher/Subscriber Monitoring Components • Shared Memory • TCP • Exchange Data Format • ROOT Interface • TPC Readout • Structure Decoding • Applications

  2. HOMER Overview - Purpose • Access to Publisher/Subscriber data stream • Examine data at any stage of P/S processing • Debugging aid • Coupled w. proper publisher components • Can provide quick access to detector data into analysis process • E.g. ROOT, but not limited to it • E.g. via • HLT-RORC • TRD DCS (work in progress) • TPC RCU/DCS (work in progress)

  3. HOMER Overview - Architecture • System has two principal parts • Tap into Publisher/Subscriber data stream • ROOT „bucket“ to be filled with data P/S Bridge P/S TCP Tap HOMER H L T N o d e P/S Ana- lysis A n a l y s i s P C ROOT Analysis TCP Reader Data Decoder P/S Bridge

  4. Publisher/Subscriber Monitoring Components • Two monitoring components • Different access to provided data • System V shared memory • TCP • Format of provided data is identical • Both are standard P/S Data sink components • Attachable to any data source or any data processor • Access to data at any point of processing chain

  5. Shared Memory Monitoring Component • ShmDumpSubscriber • Stores data into SysV shared memory buffer • When ROOT (or other client) runs on same PC • Simple flow-control via initial word in buffer • Initial word holds size of data in buffer • Zero means buffer empty • Non-zero means data is in buffer P/S Bridge Shm Dump Sub P/S Ana- lysis ROOT Analysis Shm Reader Data Decoder P/S Bridge HLT & Analysis Node

  6. TCP Monitoring Component • TCPDumpSubscriber • Accepts TCP connections on specified port • Waits for event requests • Sends next received event after request • Connection kept open until closed by client • Or until protocol error • Initial 32 bit word of received data holds size of remaining data P/S Bridge TCP Dump Sub H L T N o d e P/S Ana- lysis A n a l y s i s P C ROOT Analysis TCP Reader Data Decoder P/S Bridge

  7. Data Format • Data starts w. descriptor structures • One meta-descriptor f. whole event • Holds information about event, e.g. • Event ID • Number of data blocks/descriptors • Offset element points to data-descriptors • One data-descriptor per data block in event • Holds information about block, e.g. • Data type & origin • Size • Offset element points to data block • Descriptors are followed by actual event data blocks

  8. Data Format - Shared Memory System V Shared Memory 32 bit Size Word Meta-Descriptor Offset Data-Descriptor 0 Offset Data-Descriptor 1 Offset Data Block 0 Data Block 1

  9. Data Format - TCP Size Word Received over TCP 32 bit Size Word Data Block Received over TCP Meta-Descriptor Offset Data-Descriptor 0 Offset Data-Descriptor 1 Offset Data Block 0 Data Block 1

  10. ROOT Interface • Still work in progress • ROOT API not fully consolidated • But working already • One version: • Macro for readout from TCPDumpSubscriber • ReadTCPDumpSubscriberData.C • Class („macroable“ via .L) to decode data • AliHLT_OMShmDecoder.(h|cpp) • root> .L AliHLT_OMShmDecoder.cpp • Other possibility: • Integrate ~15 line TCP readout code into ROOT macro • Explicitly parse input data (~10-20 lines)

  11. Read TCP Data Macro • Simple ROOT Macro (ReadTCPDumpSubscriber.C) • Loadable via .L • Executable via .x • Requires hostname and port for TCPDumpSubscriber • Returns pointer to data and data size • Memory is allocated inside, has to be freed by delete [] • Handles protocol w. TCPDumpSubscriber

  12. Data Decoder • Initialized w. pointer to data and data size • Allows to query event ID • Allows to query number of data blocks • For each data block allows to query • Pointer to data • Size of data • Type of data

  13. Applications – TRD-DCS Readout Work in progress • TRD Readout • TRAPPublisher component on DCS board • Readout of TRAP chips • TCPDumpSubscriber • ROOT

  14. Applications – TRD-DCS Readout Data Flow Readout Board Readout Board TRAP1 TRAP1 . . . ... TRAP16 TRAP16 SCSN Interface A n a l y s i s P C ROOT Analysis TCP Reader Data Decoder TRAP Publisher TCPDump Subscriber DCS Board

  15. Applications Work in progress • TPC Readout • RCUPublisher component on DCS board • Readout of Altros via RCU • TCPDumpSubscriber • ROOT

  16. Applications Working • PCI Readout card • HLT-RORC Readout • ACEX Readout for TRD test setup • Attached either • TCPDumpSubscriber • ShmDumpSubscriber • Into ROOT • On same machine (Shm) • On different machine connected via network (TCP) • Used for TPC ClusterFinder Event Display

  17. Conclusion • HLT Online Monitoring is progressing • Already usable • Several scenarios imaginable & already envisioned • Should prove to be a powerful tool for debugging of analysis components, processing chains, and detectors

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