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version 1.1.2.11, 2013/09/29 20:51:12

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Using the CIM/XML Pull Operations

STATUS

<<< The TODO section is being maintained during the review and checkin process

to keep track of problems, errors, notes, etc. Must be deleted before

checkin to head of tree. Please feel free to add notes, etc in this

section as you review/test.>>>>>>

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.

d. Sort out issues with statisticalData since it really does not work

with Open and Pull operations

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.

8. XML from OOP not correctly processed.

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

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:

The operation extensions for pull operations defined in the DMTF specification

DSP0200 V 1.4 were implemented in Pegasus effective Pegasus version 2.11

including Client and Server.

These operations extend the CIM/XML individual operations to operation

sequences where the server must maintain state between operations in a

sequence and the client must execute multiple operations to get the full

set of instances or instance paths.

The following new CIM/XML operations as defined in DSP0200 are included;

-OpenEnumerateInstances

-openEnumerateInstancePaths

-OpenReferenceInstances

-OpenReferenceInstancePaths

-OpenAssociatiorInstances

-OpenAssociatorInstancePaths

-PullInstancesWithPath

-PullInstancePaths

-CloseEnumeration

-EnumerationCount

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)

is a major extension to the original CIM/XML operation concept of completely

independent operations several new pieces of functionality are implemented

to control interOperationTimeouts, counts of objects to be returned, etc.

TBD - Review this

CLIENT

The new operations follow the same pattern as the APIs for existing operations

in that:

1. All errors are handled as CIMException and Exception

2. The means of inputting parameters are the same except that there are

significantly more input parameters with the open operations and for the

first time operations return parameters as well as objects in the

response. Specifically the open and pull operations return values for

enumerationContext which is the identity for a pull sequence and

endOfSequence which is the marker the server sends in open and pull

responses when it has no more objects to send.

The significant differences include:

1. Processing of parameters on responses (i.e. the endOfSequence and

enumerationContext parameters are returned for open and pull operations).

2. Numeric arguments (Uint32 and Uint64 include the option of NULL in some

cases so they are packaged inside classes Uint32Arg and Uint64Arg in the

client api.

3. The association and reference operations ONLY process instances. They do

not include the capability to return classes like reference and associator

do and therefore return CIMInstance rather than CIMObject.

4. Paths are returned in all cases (i.e OpenEnumerateInstances and

PullInstancesWithPath where they were not with EnumeratInstances.

5. The client must maintain state between operations in a sequence (using

the enumerationContext parameter).

TBD- Are there more differences.

SERVER

The Pegasus server attempts to always deliver the requested number of objects

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

error from the providers, repository, etc. Therefore the server will reject

any request that has continueOnError = true;

Expansion to allow the continue on error may be added in a future version.

In any case, the whole purpose of the continue on error is really to allow

input from good providers to be mixed with providers that return errors so

that generally this would mean simply changing the logic in the return mechanism

to not shutdown when an error is received from any given provider.

Generally we do not believe that the providers need to do much more in the

future to support the continueOnError other than possibly allowing the provider

to continue processing after it has received an error.

PROVIDERS

This implementation requires NO changes to the 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

behavior differences primarily because the client now controls the speed of

delivery of objects.

In previous versions of Pegasus, the server attempts to deliver objects as

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

providers was the processing of each segment through the server. The server

is blocked so that no other segment can proceed through the server until that

segment is processed and sent on the network.

In the case of non-chunkedresponses, they are completely gathered in the serve

and then delivered as one non-chunked response. There were no delays for the

providers, just lots of possible memory use in the server.

The responses from providers (delivered through the deliver(...) interface are

gathered into segments of about 100 objects and this group of objects is moved

through the server to be delivered to the client.

However with the inclusion of the pull operations, The segments of objects

from the providers are cached in the server response path until the

maxObjectCount for that request (open or pull) and that number returned in a

non-chunked response. Thus, if the client is slow to issue pull requests,

the providers might be delayed at some point to reduce memory usage in the

server (the delay appears as slow response tothe deliver operation).

In other words, the time to process large sets of responses from the provider

now depends on the speed of handling the client.

It is important to remember in developing providers that the Pegasus server

can most efficiently process responses if they are passed from the provider

to the server individually or in small arrays of objects rather than the

provider gathering very large arrays of objects and sending them to the

server.

NEXT GENERATION PROVIDERS

KS_TODO

CONFIGURATION PARAMETERS

The server includes several configuration parameters to set limits on the

processing of pull operations. All of these configuration parameters are

compile time parameters rather than runtime.

1. Maximum value of minimum interoperation time. This parameter defines the

maximum time allowed between the return of an open or pull response and

the receipt of the next pull or a close operation before the server may

close the enumeration. The specification allows the server to set a

maximum interoperation time and refuse open requests that with requested

operationTimeout greater than that time.

CIM_ERR_INVALID_OPERATION_TIMEOUT

This value is set with the Pegasus environment variable

PEGASUS_PULL....

2. Maximum objects returned in a single open or pull operation. The server

can set a maximum limit on the number of objects that can be returned in

a single open or pull oepration with the maxObjectCount parameter.

3. Whether the server allows 0 as an interoperation timeout value. The value

zero is s special value for the interoperationTimeout in that it tells the

server to not timeout any enumeration sequence.

With this value for interoperationTimeout, the only way to close an

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

would remain open indefinitly. Since in Pegasus any open enumeration

context uses resources (the context object and any provider resposnes that

have not yet been issued in a response) it would appear that most

platforms would not want to allow the existence of enumeration contexts

that cannot be closed by the server.

4, maximum consecutive pull requests with 0 maxObjectCount. The use of the

pull operation with maxObjectCount set to zero could be used to keep an

enumeration context open indefinitly (this tells the server to restart the

interoperationTimeout but not send any objects in the response). Therefore the

specification allows for the server setting maximum limits on this behavior

and returning the error CIM_ERR_SERVER_LIMITS_EXCEEDED if this limit is

exceeded.

Note that this is maximum CONSECUTIVE pulls so that issuing a pull with

a non-zero count resets this counter.

KS-TBD - Is this really logical since we can still block by just issuing

lots of zero request and an occansional request for one object.

Pegaus sets the value of this limit to 1000 and allows the implementer to

modify it with the PEGASUS_MAXIMUM_ZERO_OBJECTCOUNT environment variable.

5. Default operationTimeout -

The default of this parameter is to refuse operat

In the current release of Pegasus these are all compile time parameters.

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.

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