ICD 4 — Logging Information
Contents
1. Backus Naur Form EPICS Channel Access Distributed Instrumentation Tasking System Data Handling System Distributed Real time AAO Monitor for Astronomy Experimental Physics and Industrial Control System Gemini Control System Gemini Software and Controls Group Interface Control Document Instrument Control System International Gemini Project Office Local Area Network Not Applicable indicates sections of the Gemini ICS template which do not apply for this kind of interface Observatory Control System Parameter description file Status Alarm Database Software Design Description Status Information Record Transmission Control Protocol Internet Protocol Telescope Control System User Datagram Protocol Internet Protocol A real time system obeying the ANSI IEEE 1014 1987 Versatile Backplane Bus standard Backus Naur Form A method of defining the relationship between data objects using a series of short hand symbols to represent combination choices and repetition The symbols are consists of and sequence I or selection repeating iteration 0 optional components identifier key attribute ICD 4 Logging Information icd4 3 Introduction 1 6 1 6 1 1 6 2 1 6 3 ref reference to key of another data object g end of sentence See Section 1 6 3 on page 4 for some examples Control2. Baseline DHS interface dhs_pdr_icd1c 01 Norman Hill S verin Gaudet and Dayle Kotturi HIA 7 ICD 2 Systems Status and Alarm Interface Version GSCG grp 013 ICD2 005 Kim Gillies Gemini 8m Telescopes Project 8 ICD 3 Bulk Data Transfer dhs_pdr_icd3 17 Norman Hill and S verin Gaudet HIA 9 ICD amp Non Conforming ICS Interfaces GSCG grp 012 Gemini 8m Telescopes Project 10 DHS Project Glossary dhs_project_g 02 Norman Hill Dayle Kotturi and S verin Gau det HIA 11 EPICS Archiving Reference Manual DRAFT Roger Cole Los Alamos National Labora tory N B This document is in preparation The Gemini project has a draft copy Contact the author for up to date information 12 EPICS R3 12 Channel Access Reference Manual Jeffrey O Hill Controls and Automa tion Group Los Alamos National Laboratory 13 EPICS IOC Record Reference Manual Janet B Anderson Martin R Kraimer October 1992 Los Alamos National Laboratory 14 CAPFAST Electronic Circuit Design CAE User s Manual Phase Three Logic inc Bea verton Oregon Abbreviations and Acronyms AAO Anglo Australian Observatory AR EPICS archiving tool icd4 2 ICD 4 Logging Information Introduction ARR ASCII BNF CA DITS DHS DRAMA EPICS GCS GSCG ICD ICS IGPO LAN N A OCS PDF SAD SDD SIR TCP IP TCS UDP IP VME 1 5 Glossary EPICS archive retrieval tool American Standard Code for Information Interchange
3. Created July 19 1994 Modified December 18 1996 Gemini Data Handling System Report 1 0 ICD 4 Logging Information Norman Hill Severin Gaudet dhs_pdr_icd4 11 This document defines the interfaces in the Gemini System which involve the transfer of history logging information between principal systems and the DHS Introduction 1 1 1 2 1 2 1 This document defines the interfaces in the Gemini System which involve the transfer of history logging information between principal systems and the DHS Purpose The Gemini Software Design Description 1 contains a design for the major Gemini systems An overview describing all the interfaces between the Gemini systems is given in document 3 See the list of references on page 2 for more background material This document ICD 4 Logging Information specifies those interfaces in the Gemini system which involve the transfer of logging information from Gemini principal systems to the DHS Scope Data flows covered The document covers only History logging requests and data sent from the TCS ICS OCS or DHS to the DHS Logging System during the normal course of observing These are messages generated asynchronously by the various systems and sent for logging This document does not cover 1 The handling of logging data after it is received by the DHS 2 File headers read from the Data Store 3 Engineering logs generated by the day crew or by enginee
4. LAN Local Area Network in the Gemini system devoted to the movement of com mands alarms and status information DHS Logging system The part of the DHS dedicated to monitoring the EPICS SIR records used by other systems for history logging EPICS database client A system which accesses the EPICS database by reading or writing records or registering an interest in updates to records Logging device A Gemini principal system which has information to be logged by the DHS logging system A logging device must be an EPICS database client Principal system At the highest level in the GCS software decomposition the software sys tem is divided into four kinds of software systems called principal systems The four types are called the Data Handling System the Observatory Control System the Tele scope Control System and the Instrument Control System There may be up to four concurrently executing Instrument Control Systems Subsystem A software system making up a well defined unit within one Principal system Unix A standard host level operating system The Gemini baseline for Unix is Solaris marketed by Sun Microsystems VxWorks A real time operating system for VME hardware marketed by Wind River Systems See 10 for more definitions Stylistic Conventions References to other documents References to other documents are given using a number in square brackets for example 1 The ex
5. act references are given in Section 1 3 on page 2 References to the Gemini systems The term logging system refers to that part of the Data Handling System which is responsible for handling the archiver and history logging events described in this document System commands and aitributes System commands and attribute names are given in upper case The lists of attributes required by a command and any list of components making up a data struc ture are given in Backus Naur Form BNF For example Message Command Parameters means that Message consists of Command followed by Parameters Parameters Parameter Parameter2 Parameter3 1 Not to be confused with the term Major System which is used for describing various kinds of work package icd4 4 ICD 4 Logging Information Overview means that Parameters consists of Parameter followed by an iterating sequence of Parameter2 s which may then optionally be followed by Parameter3 Parameter left right up down means that Parameter consists of a choice of one of the strings shown Section 1 5 Glos sary on page 3 contains more information 2 0 Overview The Gemini Control System GCS is made up of principal software systems the Telescope Con trol System TCS the Data Handling System DHS the Observatory Control System OCS and on
6. alarm and status han dling described in ICD 2 7 and the same Status Alarm Database used for that interface is used here also A logging device owns a EPICS SIR record to which it writes its logging informa tion The logging records for each system or subsystem should be documented in the PDF file of the system owning the record An EPICS database client can register an interest in one or more EPICS SIR records and be informed each time the record is updated Figure 3 shows the concept Compare this with Figure 3 of 7 3 2 History logging 3 2 1 When a new instrument is commissioned i e when it is installed on the system for the first time The existence of the instrument and the location of its EPICS history SIR records are registered with the logging system 3 2 2 At system start up The DHS logging system is created automatically at system startup The history logs are opened and a time stamp is written to the logs The logging system begins monitoring all EPICS history SIR records registered with the system 3 2 3 When a Gemini system or subsystem wishes to log an event A time stamped message is written to the system s EPICS logging SIR record The change to this record triggers a channel access event which the DHS logging system recognizes The contents of the log message are written to the history log 3 2 4 At system shutdown Monitoring of the EPICS history log records is stopped a time stamp is written to the log and the history
7. e or more Instrument Control Systems ICS In addition these principal systems may contain low level subsystems which are responsible for a particular area such as the Acquisition and Guidance subsystem The Software Design Description 1 describes the Gemini Control System Document 3 shows which data flows in the Gemini Control System are covered by this ICD Every system and subsystem in the GCS must be able to log events and messages so that a his tory of the tasks carried out by the various systems can be mapped The DHS logging system is the part of the DHS dedicated to receiving and storing the history log data sent by other systems This ICD covers only the logging of history information from the various systems describing the events which are happening within them This document does not constrain how the history log data will be stored 2 1 System Hardware Architecture The overall layout of the computer hardware and communication equipment is shown in Figure 1 which is taken from 3 and modified to reflect recent design decisions 2 1 1 The Observatory Control System OCS The OCS is assumed to be based on a Unix workstation baselined as a Sun Sparcstation running Solaris 2 X No other OCS architectures are currently supported 2 1 2 The Telescope Control System TCS The TCS and its subsystems are assumed to be VME based running VxWorks and EPICS No other TCS architectures are currently supported 2 1 3 The Instr
8. ed flexibly Using an ASCII string for the log ging message enables most items of information to be included Adaptability and Enhancement Potential A thin subroutine layer should be built used to extract the time stamp and message from the EPICS SIR record This will make it easier to change the logging message structure if that ever becomes necessary The interface should not hard wire the properties of the EPICS SIR record e g the maximum string length into the code The logging information should be stored in a standard format where possible so that commer cial database management software can be used to analyse the information Development and Test Factors 9 1 9 2 Project Control The project has control over the standard set of commands and parameters used for this interface New commands and parameters should only be added after consultation with the project Any new commands or parameters should be added to this document after a change control proc ess which involves a period of time for general comment The management of this document and any arbitration between the various work packages will be carried out by the Gemini project office Deliverables The Data Handling work package will deliver the thin layer of subroutines for disseminating the information contained in the history logs icd4 12 ICD 4 Logging Information Development and Test Factors The DHS work package should provide utilit
9. ields and alarm fields The status and con trol fields are all within the same database record typically they are the same field the VAL field Because the OCS EPICS SAD must provide support for non EPICS systems that do no processing in their databases ICD 2 7 defines a standard EPICS Status Information Record SIR that Gemini systems will use to provide history information to the DHS All history log ging SIR records should be named subsystem historyLog where subsystem is the identifier assigned to each subsystem by the IGPO For example the DHS history log record is named dhs historyLog 5 0 The Programmatic Interface The DHS logging system does not respond to any direct commands from other Gemini systems History logging SIR record names and ownership are determined at DHS system start up and Gemini systems send data to DHS by writing to the appropriate SIR record The DHS logging system will automatically identify the source of the message and assign a time stamp The time assigned to history records will be taken from the EIPCS time stamp assigned to the history SIR record 6 0 Debugging The DHS work package will provide an emulator which will emulate the functions described in this document The emulator will be used by the other Gemini systems to test and debug their history logging interface The emulator may simply be the EPICS ar archiving tool 7 0 Error Alarm and Logging System 7 1 Error System 7 1 1 Er
10. ies for combining together the logging information in various useful ways for example displaying all the messages from the telescope subsystems during a particular observation between specified start and end times The Observatory Control System work package will provide the EPICS Status Alarm Database The EPICS SIR record will be provided by the Gemini project office The software for transmitting commands between the major Gemini systems 4 5 and 6 will be provided by the Observatory Control System work package and Data Handling System work package as detailed in the appropriate documents The DHS logging system described in Section 3 2 on page 8 will be provided by the Data Han dling work package The EPICS Channel Access library on which these tools are based will be provided and sup ported by the EPICS group at Los Alamos National Laboratories and the IGPO 9 3 Acceptance Testing Gemini systems must be able to run in a mode which allows their communication with other Gemini systems to be tested The simulator should mimic the behaviour of this interface The DHS and OCS may need to be tested in the absence of the Status Alarm Database If the Sta tus Alarm Database is not available the messages should simply be displayed on a screen ICD 4 Logging Information icd4 13 Development and Test Factors icd4 14 ICD 4 Logging Information
11. ince this is a stateless interface system crashes are not significant events If the DHS logging system crashes logging will resume when the logging system is running again although some history messages may be missed If the logging client crashes logging of the cli ent s history will resume when the client restarts Any logging of crash or recovery events as his tory would be normal requests sent via this ICD Communication Services and Protocols Communication takes place by means of TCP IP messages communicated on the control LAN EPICS channel access communication 12 is established initially using UDP IP but run using TCP IP The messages are managed using the EPICS Channel Access protocol 12 ICD 4 Logging Information icd4 7 Behaviour TABLE 1 History Logging Events and Responses Event Response System start up The DHS logging system is created A new history log is created and opened An introductory time stamped message is written to the log The logging system starts monitoring all registered history records One of the monitored EPICS his The new value is obtained by channel access tory logging records changes state The information is written to the history log DHS system shut down Shutdown time is written to the history log The history log is closed 3 0 Behaviour 3 1 Logging System Groundwork The behaviour of the logging interface is similar to the behaviour of the
12. ini systems which need to log events are based around EPICS e g the Data Handling System and Observatory Control System When these systems need to log an event they will use a Status Alarm Database in a software only VxWorks crate as described in 7 Logging messages are written to an EPICS SIR record which resides in this database Figure 4 shows the implementation which may be compared with Figure 5 of 7 FIGURE 4 DHS Logging System Implementation of History Logging Represents a database for a Unix based System DHS Logging OCS EPICS part Unix part Status Alarm Database Client k puts logging messages l l l l l l l l l l l l Clients l put logging l messages TCS ICS 1 4 EPICS EPICS Non EPICS systems may write their logging messages into the Status Alarm Database through a Channel Access client The DHS Logging System monitors the EPICS logging records in the OCS s Status Alarm Database also with a Channel Access client In the absence of the DHS these records can also be monitored by the EPICS archiver which means that EPICS based subsystems can be tested using only the EPICS tools icd4 10 ICD 4 Logging Information The Programmatic Interface 4 2 The Representation of History Log Messages in EPICS In a standard EPICS process control environment OPI applications monitor record fields of IOC database records responding to changes in the value f
13. logs are closed icd4 8 ICD 4 Logging Information Implementation FIGURE 3 EPICS database Client EPICS SIR Record The relationship between a Logging Device EPICS SIR record and a EPICS database client EPICS database Client Status Alarm EPICS Database SIR Record l Logging Devicel Logging Device2 Subsystem Principal System 3 2 5 Recovery from crashes and power failures The history log should either be stored in a format that allows data to be retrieved after a system crash or the log should be saved automatically at regular intervals 4 0 Implementation This section should be reviewed and corrected by someone with a good understanding of EPICS and the use of the SIR records This section defines how the logging interface will be implemented in the GCS and how that implementation provides the required behaviour ICD 4 Logging Information Implementation 4 1 Why EPICS as the logging environment Every principal system in the GCS and all the individual subsystems within those principal sys tems must be able to log events on demand and they must be able to do it with the minimum of overhead They must also be able to log those events when being tested stand alone For this rea son EPICS channel access has been chosen as the method for transmitting logging information Not all of the Gem
14. o be based on a Unix workstation baselined as a Sun Sparcstation running Solaris 2 X No other DHS architectures are currently supported 2 2 Communication Architecture The TCS ICS OCS and DHS communicate with the DHS logging system using an FDDI or Ethernet Local Area Network LAN The LAN used is the one referred to as the Control LAN in other Gemini documents 2 2 1 Context Diagram Figure 2 on page 7 shows a context diagram as seen by the logging interface The Gemini sys tems appear to the interface as entities in its outside world The diagram may be compared to the Gemini Control System data flow diagrams contained in 1 icd4 6 ICD 4 Logging Information Overview FIGURE 2 2 2 2 2 3 Context Diagram Instrument Control System Telescope Control System TCS Logging ICS Logging Requests Requests a History Logging DHS Logging Requests Logging Information System Observation header data Combined Logging OCS Logging DHS Logging data Requests Requests Observatory ie Permanent Control Store System Data Handling System The DHS logging system in the data flow diagram is part of the DHS Events and Responses The events which may happen on the logging interface and the responses to those events are shown in Table 1 Refer to Section 3 0 Behaviour on page 8 for information on what causes these events S
15. ror reporting See 7 for a description of how to trigger an alarm in the Gemini system Errors should be logged using the mechanism described in this document See 2 for a description of how to report an error message from a program 7 1 2 History logging error recommendations The logging system should aim to recover from errors as best it can A fatal error while saving one logging message for example the disk filling up should not prevent it from saving further messages when the error condition has been rectified If an error occurs while writing to the log the system should notify the operator and attempt to save the incoming messages in a buffer so they can be written once the problem has been rectified If the logging system cannot write to a particular history log it should attempt to create a new history log ICD 4 Logging Information icd4 11 System Attributes 7 2 7 3 8 0 Alarm System See 7 for a description of how to trigger an alarm in the Gemini system Logging System This section is not applicable since all messages send using this interface are logged anyway System Attributes 8 1 8 1 1 8 1 2 9 0 Maintainability Interface Design Recommendations The different parts of the Gemini system may have different logging requirements e g some may need to log the value of a single number and some may wish to log an entire paragraph of text so the logging interface needs to be design
16. rs while testing or commissioning an instrument 4 The routine logging of EPICS system status using the EPICS archiver ICD 4 Logging Information icd4 1 Introduction 1 2 2 1 3 1 4 The first of these are covered in the DHS Software Design Description and the second is covered in document 8 ICD 3 Bulk Data Transfer The last two are covered in the EPICS archiv ing reference manual 11 Types of logging covered The Data Handling System is responsible for three basic types of logging 1 A database recording the use made of the system for system administrators 2 The recording of a history of the commands executed the errors reported on the system and a history of the status of the system Only the third of these types of logging is covered in this document The first two are internal to the DHS Applicable Documents The following documents should also be consulted 1 Gemini Software Design Description SPE C G0037 Gemini 8m Telescopes Project 2 Gemini Software Programming Standards SPE C G0009 02 Peregrine M McGehee Steve Wampler Gemini 8m Telescopes Project 3 Gemini System Interfaces GSCG grp 005 Gemini 8m Telescopes Project 4 ICD la The System Command Interface GSCG KKG 009 009 Kim Gillies Gemini 8m Telescopes Project 5 ICD 1b The Baseline Attribute Value Interface GSCG grp 024 Kim Gillies Steve Wampler Bret Goodrich Gemini 8m Telescopes Project 6 ICD Ic
17. ument Conirol Systems ICS A conforming ICS is VME based running VxWorks and EPICS A non conforming ICS is based on some other architecture without access to EPICS or VxWorks This document assumes the ICS architecture is conforming See 9 for a description of the inter face to a non conforming ICS ICD 4 Logging Information icd4 5 Overview FIGURE 1 The System Hardware Architecture z Primary Mirror Senay Cass Rotator A amp G Adaptive Optics Systems Systems Systems Systems Systems Instrument Detector Systems Systems Interlock System Enclosure Azimuth Altitude Rotator Adaptive Optids Instrument Systems Systems Systems VME VME VME Primary Secondary VME VME Mount VME Synchro Bus Event Bus Enclosure TCS OCS GIS VME VME VME Data LAN Control LAN IEEE 802 3 Time LAN Ti Data Reducti ime Data eduction Instrument Instrument Instrument Reference Router Router Storage Telescope Telescope Telescope Workstations Workstation _ Workstation _ Workstation Backbone Router ame orkstations Router WAN 2 1 4 The Data Handling System DHS The DHS is assumed t
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