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version 1.1.2.10, 2013/09/29 19:09:49 version 1.3, 2014/11/12 13:34:09
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         Using the CIM/XML Pull Operations          Using the CIM/XML Pull Operations and FQL query Language
  
 STATUS STATUS
  
 <<< The TODO section is being maintained during the review and checkin process  The Pull operations and FQL query language are incorporated into
 to keep track of problems, errors, notes, etc.  Must be deleted before  OpenPegasus 2.14.  This readme defines the characteristics, limitations,
 checkin to head of tree. Please feel free to add notes, etc in this  etc. for that implementation.
 section as you review/test.>>>>>>  
   
 NOTES On working with task branch.  
   
 Merge out Process  
   
    To keep our TASK branch in sync with the current head of tree we need  
    to do a regular merge out.  the TaskMakefile contains the makefile  
    procedures to do this efficiently.  NOTE: Following these procedures is  
    important in that you are merging out new material each time you do  
    the merge out.  If you were just to repeatedly merge out, you would be  
    merging previously merged changes a second time causing a real mess.  
   
     Start with new directory and put TaskMakefile above pegasus (needed so you  
     have this file for the initial operations.  
   
       make -f TaskMakefile branch_merge_out BNAME=PEP317-pullop  ## takes a long time  
   
    This checks out current head, merges it into task branch and sets tags  
    for the mergeout.  Note that at the end of this step this work is  
    part of the TASK... branch.  
   
    NOW check for conflicts, errors, etc. that resulted from the merge.  
    Look for conflict flags, compare the results (I use linux merge as a  
    good graphic compare tool) and build and test. When you are satisfied  
    that the merge out is clean, you can commit the results to the TASK...  
    branch  
   
    To commit the work to  this into Task branch  
   
       make -f mak/TaskMakefile branch_merge_out_commit BNAME=PEP317-pullop  
   
   or manually commit and finish as follows  
   
     cvs commit  
     make -f mak/TaskMakefile  branch_merge_out_finish BNAME=PEP317-pullop  
   
 ## This last step is important since it cleans up temporary tags to prepare  
    you for the next checkout  
   
 COMPARE TASKBRANCH WITH HEAD  
   
     In a new pegasus work space do same as above for merge out.  
   
     make -f TaskMakefile BNAME=PEP317-pullop  
   
     This produces a result which is all of the head merged into the branch.  
     A diff of this is all the new changes to the head of tree that you will  
     include into the merge.  
   
   
 TODO list:  
    1. Binary operation from OOP.  Need to add counter to binary  
       protocol to be able to count objects in response. Generates  
       warnings in things like messageserializer and does not work with  
       OOP right now.  
    2. OpenExecQuery - Code is incorrect in that it used InstancesWithPath  
       where the spec is instances with no path.  Need new function to wrap  
       getInstanceElement(withoutPathElement) in XmlReader.  Note that  
       Alternate is to put flag on InstancesWith Path to say no path  
    3. Code for Pull part of OpenQueryInstancesRequest a) should be part of  
       the common CIMOperationRequestDispatcher execCommon code.  
    4. The changes to WQLCIMOperationRequestDispatcher and CQL... for handling  
       pull not completed so we feed the responses back to the EnmerationContext  
       queues  
    3. Lots of minor TODOs, diagnostics, etc.  
    4. External runtime variables. Decide this as part of PEP. The variables  
       exist in CIMOperationRequestDispatcher but not in CIMConfig.  The primary  
       ones to consider are:  
       a. System maxObjectCount.  Setting some maximum size on what a pull  
           client can request (i.e. the maximum size of the maxObjectCount on  
           Open... and pull operations.  
       b. Pull interoperationTimeout (max times between operations). This is  
           the maximum number of seconds on the operationTimeout parameter of the  
           Open operations  
       c. Maximum size of the responseCache before it starts backing up  
           responses to the providers.  
    5. Decision on EnumerationContext timeout (separate thread or just  
       checks during other operations). Can we, in fact really keep the  
       enumeration context table and queue under control without monitoring  
       with a separate thread. We must monitor for:  
       a. Client operation that stop requesting (i.e. inter operation time  
           exceeds operationTimeout). Note that if it simply exceeds the time  
           the next operation does the cleanup.  The issue is those clients that  
           simply stop and do not either close or go to completion.  
       b. We should protect against providers that no not every finish delivering  
           or take to long between deliveries.  This does not exist in Pegasus  
           today  
    6. Clean up code in Dispatcher. Want to at least reduce the code for the  
       Open Operations to a set of templates so we know that the code is the  
       same for all operations.  Right now the existing operations enum, assoc,  
       etc. are all in templates but not the open operations.  Note that the  
       pull is a single template for both pullInstances and pullInstancePaths.  
       However, we might be able to reduce this to a single function by adding  
       a new level to CIMMessage.h (CommonPullResponse)  
    7. Extension to avoid double move of objects in CIMResponseData (one  
       into enumerationContext queue and second to new cimResponseData for  
       response.  Want to avoid second move by extending Open/Pull response  
       messages to include count and CIMResponse data to count objects out  
       of queue when converting (avoids the second move).  Big issue here  
       with binary data since need to extend format to count it.  
    8. NEXT TASKS:  
       a. get the pull operations rather than a template into a single  
       function by creating a new CIMPullResponse message in CIMMessage.h that  
       contains the pull data.  Then we can use a single function to process all  
       pull operations.  
       b. test the enumeration timeout thread  
       c. New Mergout to bring up to to date again.  
   
 29 September 2013. CVS update.  
 1. Modified calls to statisticalData.cpp to a) directly call with request  
    type, b) incorporate the open, pull, etc. messages.  However, since these  
    are not part of the CIM class, we must do something special with them.  
 2. Corrected OOP interface to enable new flag to indicate internal operations  
    and set host, etc.  
 3. Add code to CQLOperationsDispatcher and WQLOperationDispatcher to clean  
    up CIMResponseDataCounter after filtering.  
 4. Modified ProviderAgent to set Host info for some pull operations.  
 5. Added new flag to CIMBinMsgSerializer and Deserializer.  
   
 17 September 2013 CVS update (Actually two different updates over 3 days)  
 1. Clean up some issues in CIMMessage.h and CIMMessage.cpp  
 2. Extend OpenExecQuery to WQL and CQL processors but return not complete  
 3. Remove memory leak in EnumerationContext and EnumerationContextTable  
    handling.  
 4. Created template functions for much of the pull operations.  
 5. Reversed order of queryLanguage and query (and changed names to match  
    execQuery) in client and server.  Note that these are the execQuery  
    WQL and CQL filters and NOT FQL filters.  
 6. Some code cleanup in dispatcher  
 7. Today, passes all tests in pullop but issue in alltests. For some reason  
    not finding CIMObjectManager instance. Also, leaves enumeration contexts  
    if client terminates since cleanup thread not operating.  
   
 14 September 2013 CVS update  
 Merged out up to 25 August.  Cleaned up all operations and standardized code.  
 At this point the non pull operations code is in a set of templates but the  
 pull is not yet.  
 Fixed a significant number of problems so that it appears that the operations  
 except for OpenExecQuery run stably, at least with the pullop test program.  
 Note that there is a problem in that the Interop control provider is not  
 returning its singleton wbemserver object for some reason.  Causes a test  
 failure  
   
 Fixed for 16 June CVS Update  
    1. Cleaned up the enumerationContext and Table release functions and tested  
       to confirm that we do not lose memory in either normal sequences or  
       sequences that close early. Cleaned up pullop and added more tests  
 Taged Before: PREAUG25UPDATE and after POSTAUG25UPDATE  
   
 Fixed for 9 June CVS update  
    1. Cleaned up code for OpenQueryInstances.  Note that this is incomplete.  
       No support in WQL or CQL Operations  
    2.  
   
 What was fixed for 5 June checkin.  
    1. Extended ResponseTest MOF for for both CMPI and C++ subclasses  
    2. Fixed issues with pullop.  
    3. Fixed temp issue with CIMResponseData size by putting in mutex. That  
       is not a permanent fix but it gets around issue probably in the control  
       of the move logic that meant counts were off.  
    4. Fixed issues in Dispatcher so that associator code works. Still messy  
       code in the dispatcher.  
    5. Changed name of Enumerationtable.h & cpp to EnumerationContextTable.*  
    6  Changed name of ResponseStressTest module, classes, etc.  
   
 TAG: TASK_PEP317_5JUNE_2013_2  
   
 2 June 2013  
   
 Issues  - KS  
 1. have not installed the binary move in CIMResponseData. Please run  
 with OPP off.  
 2. Some problem in the processing so we are getting server crashes.  
 Right no I am guessing that this is in the binaryCodec and am going to  
 expand the test tools to allow testing through the localhost.  
   
 3. Still way to many TODO and KS comments and KS_TEMPS.  Removing bit by bit.  
   
 4. Env variable connection for the config parameters not installed.  
   
 5. Issue with the threaded timer.  For some reason during tests it  
 eventually calls the timer thread with trash for the parm (which is  
 pointer to the EnumerationTable object). Caught because we do a valid  
 test at beginning of the function.  
   
 6. Still using the templates in CIMOperationRequestDispatcher to simplify  
 the handle... processing.  
   
 7. I think I have a way around the double move of objects in the  
 EnumerationContext so that the outputter will just take a defined number  
 of objects directly from the gathering cache and save the second move.  
   
 8. Not yet passing all tests but getting closer now.  
   
 9. Created a tag before this commit TASK_PEP317_1JUNE_2013.  
   
 10. Next Tag will be TASK_PEP317_2_JUNE_2013 in the task branch  
   
  
 =========================================== ===========================================
   
 OVERVIEW: OVERVIEW:
  
 The operation extensions for pull operations defined in the DMTF specification The operation extensions for pull operations defined in the DMTF specification
 DSP0200 V 1.4 were implemented in Pegasus effective Pegasus version 2.11  DSP0200 V 1.4 were implemented in Pegasus effective Pegasus version 2.14
 including Client and Server. including Client and Server.
  
 These operations extend the CIM/XML  individual operations to operation These operations extend the CIM/XML  individual operations to operation
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 The following new CIM/XML operations as defined in DSP0200 are included; The following new CIM/XML operations as defined in DSP0200 are included;
  
     -OpenEnumerateInstances     -OpenEnumerateInstances
     -openEnumerateInstancePaths      -OpenEnumerateInstancePaths
     -OpenReferenceInstances     -OpenReferenceInstances
     -OpenReferenceInstancePaths     -OpenReferenceInstancePaths
     -OpenAssociatiorInstances     -OpenAssociatiorInstances
     -OpenAssociatorInstancePaths     -OpenAssociatorInstancePaths
       -OpenQueryInstances
     -PullInstancesWithPath     -PullInstancesWithPath
     -PullInstancePaths     -PullInstancePaths
       -PullInstances
     -CloseEnumeration     -CloseEnumeration
     -EnumerationCount      -EnumerationCount (deprecated by DMTF and incomplete)
      OpenExecQuery  
   
 The following  operations have not been implemented in this version of Pegasus:  
   
     -OpenQueryInstances  
   
 The following limitations on the implementation exist;  
   
 1. The filterQueryLanguage and filterQuery parameters are processed by  
    the Pegasus client but the server returns error if there is any data in  
    either parameter. This work does not include the development of the  
    query language.  Note that a separate effort to extend Pegasus to use  
    the DMTF FQL query language is in process.  
   
 2. The input parameter continueOnError is processed correctly by the client  
    but the Pegasus server only provides for false since the server does not  
    include logic to continue processing responses after an error is  
    encountered.  
    This is consistent with the statement in the specification that use of  
    this functionality is optional and the fact that the DMTF agrees that all  
    of the issues of continuing after errors have not been clarified.  
   
 3. The operation enumerationCount is not processed by the server today since  
    a) really getting the count would be the same cost as the corresponding  
    enumeration, b) the server does not include a history or estimating  
    mechanism for this to date.  
    NOTE: After a through review as part of the development of the next version  
    of CMPI we have concluded that this operation is probably not worth the  
    effort.  Since it is optional, Pegasus will only return the unknown status  
    at this point  
  
 Since the concept of sequences of operations linked together (open, pull, close) Since the concept of sequences of operations linked together (open, pull, close)
 is a major extension to the original CIM/XML operation concept of completely is a major extension to the original CIM/XML operation concept of completely
 independent operations several new pieces of functionality are implemented independent operations several new pieces of functionality are implemented
 to control interOperationTimeouts, counts of objects to be returned, etc.  to control interOperation timeouts, counts of objects to be returned, etc.
   
   NOTE: More detailed information on the pull operations is contained in:
   1. The OpenPegasus wiki (pull operations work group)
   2. The pull operations PEP (preliminary today)
   3. Presentations in the OpenPegasus wiki, in particular in the
      pull operations workgroup documentation at:
   
   https://wiki.opengroup.org/pegasus-wiki/doku.php?id=dev:workgroups:pulloperationsupportworkgroup:pull_operation_support_work_group
  
 TBD - Review this  
  
 CLIENT  OPENPEGASUS CLIENT
  
 The new operations follow the same pattern as the APIs for existing operations The new operations follow the same pattern as the APIs for existing operations
 in that: in that:
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    endOfSequence which is the marker the server sends in open and pull    endOfSequence which is the marker the server sends in open and pull
    responses when it has no more objects to send.    responses when it has no more objects to send.
  
 The significant differences include:  The significant differences between the open... and original enumerate,
   associator, and reference operations includes:
  
 1. Processing of parameters on responses (i.e. the endOfSequence and  1. The new pull client operations typically require multiple client operations
    enumerationContext parameters are returned for open and pull operations).     to retrieve a complete set of data (ex. OpenEnumerateInstances and
      PullInstancesWithPath) are equivalent to the old EnumerateInstances
      client request.
   
   2. Processing of parameters on responses (i.e. the endOfSequence and
      enumerationContext parameters are returned for open and pull operations)
      These return arguments are used to control the loop retrieving data
      for an enumeration sequence (ex. the sequence of OpenEnumerateInstances
      and PullInstancesWithPath that represents a complete enumeration
      sequence). The sequence continues until the server responds with
      EndOfSequence is true, and the enumerationContext is the identifier
      for the sequence.
  
 2. Numeric arguments (Uint32 and Uint64 include the option of NULL in some  3. Numeric arguments (Uint32 and Uint64) include the option of NULL in some
    cases so they are packaged inside classes Uint32Arg and Uint64Arg in the    cases so they are packaged inside classes Uint32Arg and Uint64Arg in the
    client api.     client API.
  
 3. The association and reference operations ONLY process instances.  They do  4. The openAsociatorInstances and openReferenceInstances operations ONLY
    not include the capability to return classes like reference and associator     process instances.  They do not include the capability to return classes
    do and therefore return CIMInstance rather than CIMObject.     as reference and associator requests do and therefore return CIMInstance
      rather than CIMObject.
  
 4. Paths are returned in all cases (i.e OpenEnumerateInstances and  5. Paths are returned for the instance operations as part of the returned
    PullInstancesWithPath where they were not with EnumeratInstances.     instances (ex. OpenEnumerateInstances and PullInstancesWithPath) where
      they were not with EnumerateInstances.
  
 5. The client must maintain state between operations in a sequence (using  6. The client must maintain state between operations in an enumeration
    the enumerationContext parameter).     sequence (using the enumerationContext parameter returned with open
      and pull responses). The client must always return the last
      enumerationContext received as the server may modify the
      enumerationContext for each response in an enumeration sequence.
  
 TBD- Are there more differences.  The client API is defined in the header file:
  
       pegasus/src/Pegasus/Client/CIMCLient.h
  
 SERVER  
  
 The Pegasus server attempts to always deliver the requested number of objects  OPENPEGASUS SERVER
 for any open or pull request (the specification allows for the server to  
 deliver less than the requested number of objects and specifically to return  
 zero objects on open).  We felt that it was worth any extra cost in processing  
 to provide the client with exactly what it had requested.  
  
 The pegasus server always closes an enumeration sequence upon receipt of any  The Pegasus server attempts to always deliver at least some objects
   in a response.  It does not wait to deliver the exact number requested but
   waits to deliver at least some. The sever will wait about 15 seconds to
   deliver and if there is nothing delivered from the providers it will then
   return a response with zero objects in it so that the client does not
   timeout.  This would only occur if the providers are extremely slow (i.e.
   greater than 15 seconds) in preparing response objects to be delivered.
   
   The Pegasus server always closes an enumeration sequence upon receipt of any
 error from the providers, repository, etc. Therefore the server will reject error from the providers, repository, etc. Therefore the server will reject
 any request that has continueOnError = true; any request that has continueOnError = true;
  
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 future to support the continueOnError other than possibly allowing the provider future to support the continueOnError other than possibly allowing the provider
 to continue processing after it has received an error. to continue processing after it has received an error.
  
 PROVIDERS  OPENPEGASUS PROVIDERS
  
 This implementation requires NO changes to the existing providers.  The  This implementation (OpenPegasus version 2.14) requires NO changes to the
 provider APIs operate just as they do with the original operations.  existing providers.  The provider APIs operate just as they do with the
   original operations.
  
 Because the server processing is different however, there may be some Because the server processing is different however, there may be some
 behavior differences primarily because the client now controls the speed of behavior differences primarily because the client now controls the speed of
 delivery of objects. delivery of objects.
  
 In previous versions of Pegasus, the server attempts to deliver objects as  In previous versions of Pegasus, the server attempted to deliver objects as
 rapidly as then can be put on the network.  In the case of HTTP chunked requests rapidly as then can be put on the network.  In the case of HTTP chunked requests
 they are delivered in chunks of about 100 objects. The primary delay for the they are delivered in chunks of about 100 objects. The primary delay for the
 providers was the processing of each segment through the server.  The server providers was the processing of each segment through the server.  The server
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 and then delivered as one non-chunked response. There were no delays for the and then delivered as one non-chunked response. There were no delays for the
 providers, just lots of possible memory use in the server. providers, just lots of possible memory use in the server.
  
 The responses from providers (delivered through the deliver(...) interface are  The responses from providers (delivered through the deliver(...) interface) are
 gathered into segments of about 100 objects and this group of objects is moved gathered into segments of about 100 objects and this group of objects is moved
 through the server to be delivered to the client. through the server to be delivered to the client.
  
 However with the inclusion of the pull operations,   The segments of objects  However with the inclusion of the pull operations, the segments (CIMResponseData
 from the providers are cached in the server response path until the  objects containing the instance or path objects) from the providers are cached
 maxObjectCount for that request (open or pull) and that number returned in a  in the server response cache until the next pull request and that number
 non-chunked response. Thus, if the client is slow to issue pull requests,  is returned in the response to that pull. Thus, if the client is slow to issue
 the providers might be delayed at some point to reduce memory usage in the  pull requests, the providers might be delayed at some point to reduce memory
 server (the delay appears as slow response tothe deliver operation).  usage in the server (the delay appears as slow response to the deliver operation).
  
 In other words, the time to process large sets of responses from the provider In other words, the time to process large sets of responses from the provider
 now depends on the speed of handling the client. now depends on the speed of handling the client.
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 provider gathering very large arrays of objects and sending them to the provider gathering very large arrays of objects and sending them to the
 server. server.
  
 NEXT GENERATION PROVIDERS  FQL (FILTER QUERY LANGUAGE)
 KS_TODO  
   The FQL implementation is complete in accord with the DMTF
   specification DSP 0212 except for a few issues including:
   
   1. The regex for the LIKE operation is the same as CQL basic. It provides
      only the following special characters   "." and  "*".
   2. The implementation does not include the comparison of
      embeddedInstances
   3. The implementation does not include the handling of Uint8[] as
      strings.
   
   For more details on the FQL implementation see the readme.txt in the
       directory pegasus/src/Pegasus/FQL.
   
   OpenPegasus will remove these limitations in a future version.
  
 CONFIGURATION PARAMETERS  The FQL implementation includes a large set of sample queries in the
   directory:
   
       pegasus/src/Pegasus/FQL/tests/Parser
   
   including both good and error generating queries.
   
   ==================================================================
   LIMITATIONS IN OPENPEGASUS 2.14
   
   1. The openQueryInstances does not allow requesting the class on response.
   
   2. The openEnumerateInstanceNames, openAssociatorNames, and openReferenceNames
   do not allow use of the query filter.  This is because
      a. The intention is to deprecate these operations completely and remove
         them in a future version
      b. They require that the server call the providers with the corresponding
         enumerate, associators, references to get the full instances to
         filter
   
   3. The filterQuery filtering is done by the server, not the providers in this
      version of OpenPegasus. This will be modified in a future version of
      OpenPegasus when the provider API extensions for the pull operations
      have been resolved.  Version 2.1 of the CMPI specification will resolve
      this issue.
   
   4. The input parameter continueOnError is processed correctly by the client
      but the Pegasus server only provides code for 'false' value, since the server
      does not include logic to continue processing responses after an error is
      encountered.
      This is consistent with the statement in the specification that use of
      this functionality is optional and the fact that the DMTF agrees that all
      of the issues of continuing after errors have not been clarified.
   
   5. The operation enumerationCount is not processed by the server today since
      a) Getting the count would be the same cost as the corresponding
      enumeration, b) the server does not include a history or estimating
      mechanism for this to date.
      NOTE: After a through review as part of the development of the next version
      of CMPI we have concluded that this operation is probably not worth the
      effort.  Since it is optional, Pegasus will only return the unknown status
      at this point. Further it is the intention of the DMTF to deprecate this
      function.
   
   ===================================================================
   PULL OPERATION CONFIGURATION PARAMETERS
  
 The server includes several configuration parameters to set limits on the The server includes several configuration parameters to set limits on the
 processing of pull operations.  All of these configuration parameters are  processing of pull operations.
 compile time parameters rather than runtime.  
   RUNTIME CONFIGURATION PARAMETERS
  
 1. Maximum value of minimum interoperation time.  This parameter defines the  1. Maximum value of interoperation time (pullOperationsMaxTimeout) -
 maximum time allowed between the return of an open or pull response and  This parameter defines the maximum time allowed between the return of an open
 the receipt of the next pull or a close operation before the server may  or pull response and the receipt of the next pull or a close operation before
 close the enumeration.  The specification allows the server to set a  the server may close the enumeration.
 maximum interoperation time and refuse open requests that with requested  The specification allows the server to set a maximum interoperation time and
 operationTimeout greater than that time.  refuse open requests that with requested operationTimeout greater than that time.
 CIM_ERR_INVALID_OPERATION_TIMEOUT  
   2. Maximum number of objects returned in a single open or pull operation
 This value is set with the Pegasus environment variable  (pullOperationsMaxObjectCount) - The server can set a maximum limit on the
 PEGASUS_PULL....  number of objects that can be returned in a single open or pull operation
   with the maxObjectCount parameter. This parameter sets the maximum limit.
 2. Maximum objects returned in a single open or pull operation.  The server  The absolute maximum allowed without recompiling (and changing a value in
 can set a maximum limit on the number of objects that can be returned in  Common/Constants.h) is 10000.
 a single open or pull oepration with the maxObjectCount parameter.  
   3. Default operationTimeout (pullOperationsdefaultTimeout) - If the client
 3. Whether the server allows 0 as an interoperation timeout value. The value  does not specify an operation timeout in the open request, the server uses
 zero is s special value for the interoperationTimeout in that it tells the  the value defined by this runtime configuration variable.  The default
 server to not timeout any enumeration sequence.  is 30 seconds.
   
   COMPILE TIME CONFIGURATION PARAMETERS
   
   1. Whether the server allows 0 as an interoperation timeout value - The value
   zero is a special value for the interoperationTimeout in that it tells the
   server to not timeout the enumeration sequence. This should never be used
   as it allows a client to open enumeration sequences that will not be
   cleaned up if the client does not properly terminate them.  There is a
   compile time variable in CIMOperationRequestDispatcher that would allow this
   to be set so 0 interoperation is allowed but we recommend that it never
   be used since it removes a significant component of the server management
   of enumerationContext information.
  
 With this value for interoperationTimeout, the only way to close an With this value for interoperationTimeout, the only way to close an
 enumeration sequence is to complete all of the pulls or issue the close. enumeration sequence is to complete all of the pulls or issue the close.
 If for some reason the sequence is not completed, that enumeration context If for some reason the sequence is not completed, that enumeration context
 would remain open indefinitly.  Since in Pegasus any open enumeration  would remain open indefinitely.  Since in Pegasus any open enumeration
 context uses resources (the context object and any provider resposnes that  context uses resources (the context object and any provider responses that
 have not yet been issued in a response) it would appear that most have not yet been issued in a response) it would appear that most
 platforms would not want to allow the existence of enumeration contexts platforms would not want to allow the existence of enumeration contexts
 that cannot be closed by the server. that cannot be closed by the server.
  
 4, maximum consecutive pull requests with 0 maxObjectCount.  The use of the  2. Maximum consecutive pull requests with 0 maxObjectCount - The use of the
 pull operation with maxObjectCount set to zero could be used to keep an pull operation with maxObjectCount set to zero could be used to keep an
 enumeration context open indefinitly (this tells the server to restart the  enumeration context open indefinitely (this tells the server to restart the
 interoperationTimeout but not send any objects in the response). Therefore the interoperationTimeout but not send any objects in the response). Therefore the
 specification allows for the server setting maximum limits on this behavior specification allows for the server setting maximum limits on this behavior
 and returning the error CIM_ERR_SERVER_LIMITS_EXCEEDED if this limit is and returning the error CIM_ERR_SERVER_LIMITS_EXCEEDED if this limit is
 exceeded. exceeded.
   
 Note that this is maximum CONSECUTIVE pulls so that issuing a pull with Note that this is maximum CONSECUTIVE pulls so that issuing a pull with
 a non-zero count resets this counter. a non-zero count resets this counter.
  
 KS-TBD - Is this really logical since we can still block by just issuing  Pegasus sets the value of this limit to 1000 and allows the implementer to
 lots of zero request and an occansional request for one object.  modify it by compiling  with the PEGASUS_MAXIMUM_ZERO_OBJECTCOUNT define  in
   CIMOperationRequestDispatcher.cpp modified.
   
   3. Time to wait for next response from providers - In the case where providers
   are responding very slowly, the goal is to generate responses with
   zero instances at regular intervals to allow the client to keep the
   enumeration context alive.  This wait time is set by a compile time define
   (PEGASUS_PULL_MAX_OPERATION_WAIT_SEC)in pegasus/src/Pegasus/Common/Constants.h
   and is set to 15 seconds in the current release.
   
   4. Time to wait before killing off an enumeration context that is blocked
   by missing provider responses. In the rare case where providers do not complete
   their responses to the server there is a compile-time counter that trys to
   clean up the providers and finally just kill the enumeration sequence after
   a defined number of consecutive pulls that return zero objects.
   The limit is defined in pegasus/src/Pegasus/Constants.h
   
   NOTE: The development team is trying to consolidate all such constants and
   #define definitions that control overall server characteristics but are not
   runtime parameters in Constants.h
  
 Pegaus sets the value of this limit to 1000 and allows the implementer to  ===================================================================
 modify it with the PEGASUS_MAXIMUM_ZERO_OBJECTCOUNT environment variable.  TESTING
  
 5. Default operationTimeout -  The pull operations are tested primarily with two client programs in the
   directory Pegasus/Client/tests
   
   1. pullop and it corresponding Makefile provide extensive tests of the
      pull operations and comparison of the results with the corresponding non
      pull operations.
  
 The default of this parameter is to refuse operat  2. PullErrors  tests a number of error scenarios with the pull operations.
   
   3. cimcli has been extended to allow execution of the pull operations with new
      operations that parallel the existing operations:
      enumerateinstances(ei) - corresponding is pullenumerateInstances(pei)
      ni -> pni   enumerateInstanceNames
      r -> pr     references
      rn -> prn   referenceNames
      a  -> pa    associators
      ar -> par   associatorNames
   
      These execute complete pull sequences (open, pull) with cimcli options
      to control parameters like maxObjectCount, interoperation Timeout, etc.
   
   
   =============================================================
   TODO LIST - Post 2.14 release
      1. Binary operation from OOP.  Need to add counter to binary
         protocol to be able to count objects in response. Generates
         warnings in things like messageserializer and does not work with
         OOP right now.  Fixed by converting to XML. Concluded that we do not
         need to do this. The binary response is not really used often
         in the current environment So double mapping it is not a major issue.
         Leave this as FUTURE
      2. Minor TODOs, diagnostics, etc. still in the code. Reduced almost to
         none now.  We are leaving some in as PEGASUS_DEBUG
      3. Extension to avoid double move of objects in CIMResponseData (one
         into enumerationContext queue and second to new cimResponseData for
         response.  Want to avoid second move by extending Open/Pull response
         messages to include count and CIMResponse data to count objects out
         of queue when converting (avoids the second move). This would mean
         extending the output writers to allow the count field to be supplied
         so they would only create output for up to the count supplied.(Make
         this future beyond bug 9676). This is fairly extensive because it
         extends beyond CIMResponseData to SCMO and XML writers where the
         XmlWriters used by encodeXmlResponse would have to have counters
         added. Then instead of copying on getCache we would simply pass the
         cache and count on and the writer would take and remove.
      4. Add more static tests (currently only OpenEnumerateInstances and
         OpenEnumerateInstanceNames covered).
      5. Correct issue between operations and HTTP where we are sending
         trailers with exceptions. Modify response mechanisms so that we
         set non-chunked for all responses where we send error responses to
         avoid the trailers. NOTE: There should be now a bug on this in general
         where we would want to send an initial error without the trailer. Should
         have always done that.
      6. It would be more efficient in dispatcher to always use exception for
          rejects and change the _reject functions so that they never return
          when they reject. This is VERY LOW PRIORITY and primarily saves
          a few lines of code in the reject functions and their calls.  Means we
          would code.
          _rejectIfEnumerationToBroad(...);
          _rejectIfThisParameterIncorrect(...);
   
          instead of
          if (_rejectIfEnum...)
          {
              return true
          }
          It would mean that the method trace for the handlers would not return
          an exit if we rejected. VERY LOW PRIORITY. Possibly FUTURE. No behavior
          change, just more compact source code but it messes with the method
          trace logic.
       7. There are still a couple of template functions around the task of
          distributing requests to the multiple providers.
          In fact there are two similar but different templates for
          the associators(i.e. assoc, ref, etc.) functions and the parallel
          openAssoc functions.  It would be nice to consolidate that logic and
          further to try to create a non-template form for those functions. LOW
          PRIORITY
       8. Trace functions in CIMResponseData,h & cpp should be PEGASUS_DEBUG.
          Same for trace function in EnumerationContext and
          EnumerationContextTable
       9. Question. We added trace in CIMRequestOperationDispatcher.cpp if
          query enum is recevied with no object path.  However, since this is
          a provider problem should we be doing something other than a trace
          (ex. log) since traces are often not really used and they do generate
          lots of data whereby something like this could get lost. Also, need
          to review what level of trace if we keep trace.
      10. Better statistics keeping for open, etc. through cimperf.
      11. Incorporate a simple test of pull operations into the TestClient
      12. Define a simpler iteration interface for the client so that
          the client does not have to directly control the open, pull, etc.
          operations.
  
 In the current release of Pegasus these are all compile time parameters.  


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Removed from v.1.1.2.10  
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  Added in v.1.3

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