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  1 karl  1.1.2.1         Using the CIM/XML Pull Operations
  2               
  3               STATUS
  4               
  5 karl  1.1.2.4 <<< The TODO section is being maintained during the review and checkin process
  6 karl  1.1.2.1 to keep track of problems, errors, notes, etc.  Must be deleted before
  7               checkin to head of tree. Please feel free to add notes, etc in this
  8               section as you review/test.>>>>>>
  9               
 10 karl  1.1.2.5 NOTES On working with task branch.
 11               
 12 karl  1.1.2.6 Merge out Process
 13 karl  1.1.2.5 
 14 karl  1.1.2.6    To keep our TASK branch in sync with the current head of tree we need
 15                  to do a regular merge out.  the TaskMakefile contains the makefile
 16                  procedures to do this efficiently.  NOTE: Following these procedures is
 17                  important in that you are merging out new material each time you do
 18                  the merge out.  If you were just to repeatedly merge out, you would be
 19                  merging previously merged changes a second time causing a real mess.
 20               
 21                   Start with new directory and put TaskMakefile above pegasus (needed so you
 22                   have this file for the initial operations.  
 23               
 24                     make -f TaskMakefile branch_merge_out BNAME=PEP317-pullop  ## takes a long time
 25               
 26                  This checks out current head, merges it into task branch and sets tags
 27                  for the mergeout.  Note that at the end of this step this work is
 28                  part of the TASK... branch.
 29               
 30                  NOW check for conflicts, errors, etc. that resulted from the merge.
 31                  Look for conflict flags, compare the results (I use linux merge as a
 32                  good graphic compare tool) and build and test. When you are satisfied
 33                  that the merge out is clean, you can commit the results to the TASK...
 34                  branch
 35 karl  1.1.2.5    
 36 karl  1.1.2.6    To commit the work to  this into Task branch
 37 karl  1.1.2.5 
 38 karl  1.1.2.6       make -f mak/TaskMakefile branch_merge_out_commit BNAME=PEP317-pullop
 39 karl  1.1.2.5 
 40                 or manually commit and finish as follows
 41               
 42 karl  1.1.2.6     cvs commit
 43                   make -f mak/TaskMakefile  branch_merge_out_finish BNAME=PEP317-pullop
 44 karl  1.1.2.5 
 45 karl  1.1.2.6 ## This last step is important since it cleans up temporary tags to prepare
 46                  you for the next checkout
 47 karl  1.1.2.5    
 48               COMPARE TASKBRANCH WITH HEAD
 49               
 50 karl  1.1.2.7     In a new pegasus work space do same as above for merge out.
 51 karl  1.1.2.5 
 52 karl  1.1.2.7     make -f TaskMakefile BNAME=PEP317-pullop
 53 karl  1.1.2.5 
 54 karl  1.1.2.7     This produces a result which is all of the head merged into the branch.
 55                   A diff of this is all the new changes to the head of tree that you will
 56                   include into the merge.
 57 karl  1.1.2.5 
 58 karl  1.1.2.3 
 59 karl  1.1.2.4 TODO list:
 60 karl  1.1.2.3    1. Binary operation from OOP.  Need to add counter to binary
 61                     protocol to be able to count objects in response. Generates
 62                     warnings in things like messageserializer and does not work with
 63                     OOP right now.
 64 karl  1.1.2.4    2. OpenExecQuery - Code is incorrect in that it used InstancesWithPath
 65                     where the spec is instances with no path.  Need new function to wrap
 66                     getInstanceElement(withoutPathElement) in XmlReader.  Note that
 67                     Alternate is to put flag on InstancesWith Path to say no path
 68                  3. Code for Pull part of OpenQueryInstancesRequest a) should be part of
 69                     the common CIMOperationRequestDispatcher execCommon code.
 70                  4. The changes to WQLCIMOperationRequestDispatcher and CQL... for handling
 71                     pull not completed so we feed the responses back to the EnmerationContext
 72                     queues
 73 karl  1.1.2.7    3. Lots of minor TODOs, diagnostics, etc.
 74 karl  1.1.2.4    4. External runtime variables. Decide this as part of PEP. The variables
 75                     exist in CIMOperationRequestDispatcher but not in CIMConfig.  The primary
 76                     ones to consider are:
 77                     a. System maxObjectCount.  Setting some maximum size on what a pull
 78                         client can request (i.e. the maximum size of the maxObjectCount on
 79                         Open... and pull operations.
 80                     b. Pull interoperationTimeout (max times between operations). This is
 81                         the maximum number of seconds on the operationTimeout parameter of the
 82                         Open operations
 83                     c. Maximum size of the responseCache before it starts backing up
 84                         responses to the providers.
 85 karl  1.1.2.3    5. Decision on EnumerationContext timeout (separate thread or just
 86 karl  1.1.2.4       checks during other operations). Can we, in fact really keep the 
 87                     enumeration context table and queue under control without monitoring
 88                     with a separate thread. We must monitor for:
 89                     a. Client operation that stop requesting (i.e. inter operation time
 90                         exceeds operationTimeout). Note that if it simply exceeds the time
 91                         the next operation does the cleanup.  The issue is those clients that
 92                         simply stop and do not either close or go to completion.
 93                     b. We should protect against providers that no not every finish delivering
 94                         or take to long between deliveries.  This does not exist in Pegasus
 95                         today
 96 karl  1.1.2.8    6. Clean up code in Dispatcher. Want to at least reduce the code for the
 97                     Open Operations to a set of templates so we know that the code is the
 98                     same for all operations.  Right now the existing operations enum, assoc,
 99                     etc. are all in templates but not the open operations.  Note that the
100                     pull is a single template for both pullInstances and pullInstancePaths.
101                     However, we might be able to reduce this to a single function by adding
102                     a new level to CIMMessage.h (CommonPullResponse)
103 karl  1.1.2.3    7. Extension to avoid double move of objects in CIMResponseData (one
104                     into enumerationContext queue and second to new cimResponseData for
105                     response.  Want to avoid second move by extending Open/Pull response
106                     messages to include count and CIMResponse data to count objects out
107                     of queue when converting (avoids the second move).  Big issue here
108                     with binary data since need to extend format to count it.
109 karl  1.1.2.8    8. NEXT TASKS: 
110                     a. get the pull operations rather than a template into a single
111                     function by creating a new CIMPullResponse message in CIMMessage.h that
112                     contains the pull data.  Then we can use a single function to process all
113                     pull operations.
114 karl  1.1.2.9       b. test the enumeration timeout thread
115 karl  1.1.2.8       c. New Mergout to bring up to to date again.
116 karl  1.1.2.10 
117                29 September 2013. CVS update.
118                1. Modified calls to statisticalData.cpp to a) directly call with request
119                   type, b) incorporate the open, pull, etc. messages.  However, since these
120                   are not part of the CIM class, we must do something special with them.
121                2. Corrected OOP interface to enable new flag to indicate internal operations
122                   and set host, etc.
123                3. Add code to CQLOperationsDispatcher and WQLOperationDispatcher to clean
124                   up CIMResponseDataCounter after filtering.
125                4. Modified ProviderAgent to set Host info for some pull operations.
126                5. Added new flag to CIMBinMsgSerializer and Deserializer.
127 karl  1.1.2.8  
128 karl  1.1.2.9  17 September 2013 CVS update (Actually two different updates over 3 days)
129                1. Clean up some issues in CIMMessage.h and CIMMessage.cpp
130                2. Extend OpenExecQuery to WQL and CQL processors but return not complete
131                3. Remove memory leak in EnumerationContext and EnumerationContextTable
132                   handling.
133                4. Created template functions for much of the pull operations.
134                5. Reversed order of queryLanguage and query (and changed names to match
135                   execQuery) in client and server.  Note that these are the execQuery
136                   WQL and CQL filters and NOT FQL filters.
137                6. Some code cleanup in dispatcher
138                7. Today, passes all tests in pullop but issue in alltests. For some reason
139                   not finding CIMObjectManager instance. Also, leaves enumeration contexts
140                   if client terminates since cleanup thread not operating.
141                
142 karl  1.1.2.8  14 September 2013 CVS update
143                Merged out up to 25 August.  Cleaned up all operations and standardized code.
144                At this point the non pull operations code is in a set of templates but the
145                pull is not yet.
146                Fixed a significant number of problems so that it appears that the operations
147                except for OpenExecQuery run stably, at least with the pullop test program.
148                Note that there is a problem in that the Interop control provider is not
149                returning its singleton wbemserver object for some reason.  Causes a test
150                failure
151 karl  1.1.2.7  
152                Fixed for 16 June CVS Update
153                   1. Cleaned up the enumerationContext and Table release functions and tested
154                      to confirm that we do not lose memory in either normal sequences or
155                      sequences that close early. Cleaned up pullop and added more tests
156 karl  1.1.2.8  Taged Before: PREAUG25UPDATE and after POSTAUG25UPDATE
157 karl  1.1.2.4  
158                Fixed for 9 June CVS update
159                   1. Cleaned up code for OpenQueryInstances.  Note that this is incomplete.
160                      No support in WQL or CQL Operations
161                   2. 
162                
163                What was fixed for 5 June checkin.
164 karl  1.1.2.3     1. Extended ResponseTest MOF for for both CMPI and C++ subclasses
165                   2. Fixed issues with pullop.
166                   3. Fixed temp issue with CIMResponseData size by putting in mutex. That
167                      is not a permanent fix but it gets around issue probably in the control
168                      of the move logic that meant counts were off.
169                   4. Fixed issues in Dispatcher so that associator code works. Still messy
170                      code in the dispatcher.
171                   5. Changed name of Enumerationtable.h & cpp to EnumerationContextTable.*
172                   6  Changed name of ResponseStressTest module, classes, etc.
173                
174                TAG: TASK_PEP317_5JUNE_2013_2
175                
176 karl  1.1.2.2  2 June 2013
177 karl  1.1.2.1  
178                Issues  - KS
179                1. have not installed the binary move in CIMResponseData. Please run
180                with OPP off.
181                2. Some problem in the processing so we are getting server crashes.
182                Right no I am guessing that this is in the binaryCodec and am going to
183                expand the test tools to allow testing through the localhost.
184                
185                3. Still way to many TODO and KS comments and KS_TEMPS.  Removing bit by bit.
186                
187                4. Env variable connection for the config parameters not installed.
188                
189                5. Issue with the threaded timer.  For some reason during tests it
190                eventually calls the timer thread with trash for the parm (which is
191                pointer to the EnumerationTable object). Caught because we do a valid
192                test at beginning of the function.
193                
194 karl  1.1.2.2  6. Still using the templates in CIMOperationRequestDispatcher to simplify
195                the handle... processing.  
196                
197                7. I think I have a way around the double move of objects in the
198                EnumerationContext so that the outputter will just take a defined number
199                of objects directly from the gathering cache and save the second move.
200                
201                8. Not yet passing all tests but getting closer now.
202                
203                9. Created a tag before this commit TASK_PEP317_1JUNE_2013.
204                
205                10. Next Tag will be TASK_PEP317_2_JUNE_2013 in the task branch
206                
207                
208 karl  1.1.2.1  ===========================================
209                
210                OVERVIEW:
211                
212                The operation extensions for pull operations defined in the DMTF specification
213                DSP0200 V 1.4 were implemented in Pegasus effective Pegasus version 2.11
214                including Client and Server.
215                
216                These operations extend the CIM/XML  individual operations to operation
217                sequences where the server must maintain state between operations in a
218                sequence and the client must execute multiple operations to get the full
219                set of instances or instance paths.
220                
221                The following new CIM/XML operations as defined in DSP0200 are included;
222                
223                    -OpenEnumerateInstances
224                    -openEnumerateInstancePaths
225                    -OpenReferenceInstances
226                    -OpenReferenceInstancePaths
227                    -OpenAssociatiorInstances
228                    -OpenAssociatorInstancePaths
229 karl  1.1.2.1      -PullInstancesWithPath
230                    -PullInstancePaths
231                    -CloseEnumeration
232                    -EnumerationCount
233 karl  1.1.2.2       OpenExecQuery
234 karl  1.1.2.1  
235                The following  operations have not been implemented in this version of Pegasus:
236                
237                    -OpenQueryInstances
238                
239                The following limitations on the implementation exist;
240                
241                1. The filterQueryLanguage and filterQuery parameters are processed by
242                   the Pegasus client but the server returns error if there is any data in
243 karl  1.1.2.2     either parameter. This work does not include the development of the
244                   query language.  Note that a separate effort to extend Pegasus to use
245                   the DMTF FQL query language is in process.
246 karl  1.1.2.1  
247                2. The input parameter continueOnError is processed correctly by the client
248                   but the Pegasus server only provides for false since the server does not
249                   include logic to continue processing responses after an error is
250                   encountered. 
251                   This is consistent with the statement in the specification that use of 
252                   this functionality is optional and the fact that the DMTF agrees that all 
253                   of the issues of continuing after errors have not been clarified.  
254                
255                3. The operation enumerationCount is not processed by the server today since
256                   a) really getting the count would be the same cost as the corresponding
257                   enumeration, b) the server does not include a history or estimating
258                   mechanism for this to date.
259 karl  1.1.2.2     NOTE: After a through review as part of the development of the next version
260                   of CMPI we have concluded that this operation is probably not worth the
261                   effort.  Since it is optional, Pegasus will only return the unknown status
262                   at this point
263 karl  1.1.2.1  
264                Since the concept of sequences of operations linked together (open, pull, close)
265                is a major extension to the original CIM/XML operation concept of completely
266                independent operations several new pieces of functionality are implemented
267                to control interOperationTimeouts, counts of objects to be returned, etc.
268                
269                TBD - Review this
270                
271                CLIENT
272                
273                The new operations follow the same pattern as the APIs for existing operations
274                in that:
275                
276                1. All errors are handled as CIMException and Exception
277                
278                2. The means of inputting parameters are the same except that there are
279                   significantly more input parameters with the open operations and for the 
280                   first time operations return parameters as well as objects in the 
281                   response.  Specifically the open and pull operations return values for 
282                   enumerationContext which is the identity for a pull sequence and 
283                   endOfSequence which is the marker the server sends in open and pull 
284 karl  1.1.2.1     responses when it has no more objects to send.
285                
286                The significant differences include:
287                
288                1. Processing of parameters on responses (i.e. the endOfSequence and
289                   enumerationContext parameters are returned for open and pull operations).
290                
291                2. Numeric arguments (Uint32 and Uint64 include the option of NULL in some
292                   cases so they are packaged inside classes Uint32Arg and Uint64Arg in the
293                   client api.
294                
295                3. The association and reference operations ONLY process instances.  They do
296                   not include the capability to return classes like reference and associator
297                   do and therefore return CIMInstance rather than CIMObject.
298                
299                4. Paths are returned in all cases (i.e OpenEnumerateInstances and
300                   PullInstancesWithPath where they were not with EnumeratInstances.
301                
302                5. The client must maintain state between operations in a sequence (using
303                   the enumerationContext parameter).
304                
305 karl  1.1.2.1  TBD- Are there more differences.
306                
307                
308                SERVER
309                
310                The Pegasus server attempts to always deliver the requested number of objects
311                for any open or pull request (the specification allows for the server to
312                deliver less than the requested number of objects and specifically to return
313                zero objects on open).  We felt that it was worth any extra cost in processing
314                to provide the client with exactly what it had requested.
315                
316                The pegasus server always closes an enumeration sequence upon receipt of any
317                error from the providers, repository, etc. Therefore the server will reject
318 karl  1.1.2.2  any request that has continueOnError = true;
319                
320                Expansion to allow the continue on error may be added in a future version.
321                In any case, the whole purpose of the continue on error is really to allow
322                input from good providers to be mixed with providers that return errors so
323                that generally this would mean simply changing the logic in the return mechanism 
324                to not shutdown when an error is received from any given provider.
325                
326                Generally we do not believe that the providers need to do much more in the
327                future to support the continueOnError other than possibly allowing the provider
328                to continue processing after it has received an error.
329 karl  1.1.2.1  
330                PROVIDERS
331                
332                This implementation requires NO changes to the existing providers.  The
333                provider APIs operate just as they do with the original operations.
334                
335                Because the server processing is different however, there may be some
336                behavior differences primarily because the client now controls the speed of
337                delivery of objects.
338                
339                In previous versions of Pegasus, the server attempts to deliver objects as
340                rapidly as then can be put on the network.  In the case of HTTP chunked requests
341                they are delivered in chunks of about 100 objects. The primary delay for the
342                providers was the processing of each segment through the server.  The server
343                is blocked so that no other segment can proceed through the server until that
344                segment is processed and sent on the network.
345                In the case of non-chunkedresponses, they are completely gathered in the serve
346                and then delivered as one non-chunked response. There were no delays for the
347                providers, just lots of possible memory use in the server.
348                
349                The responses from providers (delivered through the deliver(...) interface are
350 karl  1.1.2.1  gathered into segments of about 100 objects and this group of objects is moved
351                through the server to be delivered to the client.
352                
353                However with the inclusion of the pull operations,   The segments of objects
354                from the providers are cached in the server response path until the 
355                maxObjectCount for that request (open or pull) and that number returned in a
356                non-chunked response. Thus, if the client is slow to issue pull requests,
357                the providers might be delayed at some point to reduce memory usage in the
358                server (the delay appears as slow response tothe deliver operation).
359                
360                In other words, the time to process large sets of responses from the provider
361                now depends on the speed of handling the client.
362                
363                It is important to remember in developing providers that the Pegasus server
364                can most efficiently process responses if they are passed from the provider
365                to the server individually or in small arrays of objects rather than the
366                provider gathering very large arrays of objects and sending them to the
367                server.
368                
369 karl  1.1.2.2  NEXT GENERATION PROVIDERS
370                KS_TODO
371                
372 karl  1.1.2.1  CONFIGURATION PARAMETERS
373                
374                The server includes several configuration parameters to set limits on the
375                processing of pull operations.  All of these configuration parameters are
376                compile time parameters rather than runtime.
377                
378                1. Maximum value of minimum interoperation time.  This parameter defines the
379                maximum time allowed between the return of an open or pull response and 
380                the receipt of the next pull or a close operation before the server may 
381                close the enumeration.  The specification allows the server to set a 
382                maximum interoperation time and refuse open requests that with requested 
383                operationTimeout greater than that time.  
384                CIM_ERR_INVALID_OPERATION_TIMEOUT
385                
386                This value is set with the Pegasus environment variable
387                PEGASUS_PULL....
388                
389                2. Maximum objects returned in a single open or pull operation.  The server
390                can set a maximum limit on the number of objects that can be returned in
391                a single open or pull oepration with the maxObjectCount parameter.
392                
393 karl  1.1.2.1  3. Whether the server allows 0 as an interoperation timeout value. The value
394                zero is s special value for the interoperationTimeout in that it tells the
395                server to not timeout any enumeration sequence.
396                
397                With this value for interoperationTimeout, the only way to close an 
398                enumeration sequence is to complete all of the pulls or issue the close.  
399                If for some reason the sequence is not completed, that enumeration context 
400                would remain open indefinitly.  Since in Pegasus any open enumeration 
401                context uses resources (the context object and any provider resposnes that 
402                have not yet been issued in a response) it would appear that most 
403                platforms would not want to allow the existence of enumeration contexts 
404                that cannot be closed by the server.  
405                
406                4, maximum consecutive pull requests with 0 maxObjectCount.  The use of the
407                pull operation with maxObjectCount set to zero could be used to keep an
408                enumeration context open indefinitly (this tells the server to restart the
409                interoperationTimeout but not send any objects in the response). Therefore the
410                specification allows for the server setting maximum limits on this behavior
411                and returning the error CIM_ERR_SERVER_LIMITS_EXCEEDED if this limit is
412                exceeded.
413                Note that this is maximum CONSECUTIVE pulls so that issuing a pull with
414 karl  1.1.2.1  a non-zero count resets this counter.
415                
416                KS-TBD - Is this really logical since we can still block by just issuing
417                lots of zero request and an occansional request for one object.
418                
419                Pegaus sets the value of this limit to 1000 and allows the implementer to
420                modify it with the PEGASUS_MAXIMUM_ZERO_OBJECTCOUNT environment variable.
421                
422                5. Default operationTimeout - 
423                
424                The default of this parameter is to refuse operat
425                
426                In the current release of Pegasus these are all compile time parameters.

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