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From "Sorin S." <ssu...@gmail.com>
Subject Re: [jira] Updated: (QPID-2835) Implement connections (CON) operational logging on 0-10
Date Fri, 10 Sep 2010 11:23:18 GMT
Hi Martin,
Thank you for commenting on this, appreciate your input as always. You
might have seen the email Andrew sent earlier, which outlined a
possible scenario to improve the logging framework - these are just
different options we are looking at in order to provide operational
logging on version 0-10 with an eye on forthcoming 1.0.
As a first step I have placed all the log formats in a single class
and static import them in the subsequent implementation classes and
also  streamlined the patches a bit (eg removed hard coded formatting,
I am sure we will ultimately come to an agreeable solution that would
be suitable in the long term.



On Mon, Sep 6, 2010 at 2:35 AM, Martin Ritchie <ritchiem@apache.org> wrote:
> On 2 September 2010 10:53, Sorin S. <ssuciu@gmail.com> wrote:
>> Hi Martin,
>> Thanks very much for your feedback.
>> The main problem I had with the current framework is the fact that the
>> LogSubject objects seem to have knowledge about broker hierarchy (eg
>> the SubscriptionLogSubject instantiates a QueueLogSubject, also the
>> ConnectionLogSubject takes a AMQProtocolSession which is pre 0-10,
>> etc) -
>> this makes those LogSubject(s) hard to re-use and things can get even
>> harder if 1-0 comes with a different Model Object hierarchy.
> Hi Sorin,
> Thanks for taking the time to add some explanation, but I still can't
> see the need for the changes you are proposing.
> A subscription is a 'subscription to a queue' therefore it delegates
> to the QueueLogSubject to perform that logging. It would be wrong for
> the SubscriptionLogSubject to know how to log queues. There is no
> knowledge of a broker hierarchy only that a subscription involves a
> queue, but I don't think this is much of a mental leap.
> I totally agree with you about the AMQProtocolSession, as you
> highlight this is a concrete implementation class for a particular
> protocol. As I mentioned off list I would have expected the
> LogSubjects to use the Model classes AMQConnectionModel and
> AMQSessionModel. At this level of abstraction the logging would not
> know about the protocol in use only the details that it was desirable
> to log about. These model classes were added after the Logging
> framework so it is only natural that they are not being used.
>> Given the LogSubject role is to provide a subject (ultimately a label)
>> to the business message pertaining to a broker specific Object state I
>> thought that the object itself is in the best position to have all the
>> information needed to generate the log subject and therefore the
>> logging framework can consist of a GenericLogActor which would take
>> something like:
>> (LogSubject) Object
>> and format it using the selected method from a class generated from
>> o.a.q.server.logging.messages.*_logmessages.properties (where the
>> formatting takes place). So our Model Object encapsulates all the info
>> needed to log itself up.
> The business objects should only perform their primary function so
> should not have anything to do with logging. If you make it perform
> more than one primary operation then it becomes difficult to replace
> or extend only one of those functions. Keeping the functionality
> isolated is part of a good design. The role of the LogSubject is to
> provide an coupling between the broker code and the logging code. The
> LogSubjects allow the creation of an identifier for each of the broker
> Model objects. This information is not required by the Model objects
> to do their job and it is not required by the logging framework, the
> LogSubjects are there to encapsulate the extraction of Model
> properties and ultimately the formatting of a log string.
> I really don't see why the Broker model should know anything about
> logging its primary purpose is message delivery not logging.
>> This allows decoupling of the logging framework from the need to know
>> anything about the objects it logs, it only needs to call the
>> toLogString method defined in the LogSubject interface. It could also
>> log anything implementing a LogSubject interface via the same
>> GenericActor. Otherwise we might need to create new Actors and
>> LogSubject's to fit any new Model Object which doesn't seem right to
>> me.
> By doing this you are coupling the the format of the log message with
> the business of maintaining a connection or a session. Sure the
> logging logging framework doesn't need to know about the the objects
> it is logging but that was the case before you started this work. The
> Loggers would work in any application, the binding between Qpid and
> the LogActor framework are the LogSubjects. By having the three
> components each with a single responsibility we can maintain a series
> of clean interfaces which are easier to test and maintain and
> therefore understand.
>> As of now, with the proposed patches, the 0-10 operational logging
>> works independent of the pre 0-10 one and I think it is simpler and
>> more flexible.
> However, your current patches are suggesting that the 0-8/9, 0-10 and
> future 1-0 objects will all have to have their own log formatting.
> This will lead to inconsistency at best, at worse we will have three
> copies of the same log format to maintain. By abstracting and using a
> model the LogSubjects become independent of implementation details and
> provide a single place to maintain and understand how logging of a
> broker model is performed.
>> This is why Qpid-2835 seems inconsistent with the 0-8/0-9, as it is
>> designed to sit alongside the current framework.
>> If agreed and within the planned October release scope, we can
>> refactor the current implementation also, effectively reducing the
>> logging framework to a LogSubject interface, a GenericActor and
>> o.a.q.server.logging.messages.* classes, still obeying the schema you
>> highlighted:
>> LogActors <-> Logging Framework
>> LogActors <-> Model Objects
>> but we might as well leave it as it is.
> What you are suggesting does not follow the clean abstraction
> highlighted above. If you remove the the Logging framework you will be
> left with dead code in your model objects in the form of the
> toLogString() methods. How is this a good design?
> I really think the removal of the concrete LogSubjects and LogActors
> is a backward step for logging. Introducing logging to the 0-10
> protocol should be a very quick process, it is just a case of adding
> the right logging calls in the 0-10 code base, exposing the required
> state from the 0-10 model objects and changing the LogSubjects to use
> model interfaces. Logging should know nothing about the protocol
> version. I see your patches have the new 0-10 code calls, we just need
> finish the integration of the 0-10 protocol to the broker.
>> The move to slf4j is something very good to have, but it requires
>> major changes as you know. Once we have it, we can hook it at the
>> o.a.q.server.logging.rawloggers level. But to achieve that, we need to
>> give up the log4j.xml file watching, the org.apache.log4j packages (eg
>> the QpidCompositeRollingAppender), we have jmx console issues to take
>> care of, couple of hardcoded places to look at and about 94 straight
>> changes, not to mention the testing framework as well. All in all, not
>> a trivial move but doable nevertheless.
> I'm not sure what you mean by moving to slf4j as requiring major
> changes. It has never been mentioned that we should migrate the broker
> code base away from log4j. I can see how once we have fully split the
> broker in to modules and are able to load them into an OSGi container
> that being able to select a logger other than log4j may have benefits.
> The current framework does not and should not reference log4j anywhere
> outside of the Log4jMessageLogger. If you wanted to use slf4j then it
> is a simple matter of making a new MessageLogger.
>> I would be very interested to hear thoughts on the above from anyone
>> on the list.
> As I mentioned above I have had a quick look through your patches and
> I'm not in favour of moving the logging into the business logic. Think
> of it this way, if you can't test a piece of functionality in
> isolation then there is a problem with the design. To test your
> logging formatters you are going to have to instantiate or mock out
> the entire connection. Logging has nothing to do with the connection
> logic only attributes of the connection. So you should only need a
> mock connection, but by embedding the logging formatters in the
> connection you cannot use a mock connection.
> Martin
>> Thank you,
>> Sorin
>> On Wed, Sep 1, 2010 at 7:12 PM, Martin Ritchie <ritchiem@apache.org> wrote:
>>> Hi Sorin,
>>> I've been watching your changes wrt the Operational Logging apologies
>>> for not replying to your thread over the weekend but I wasn't at a
>>> computer.
>>> I think the addition of the toLogString() is the wrong approach here.
>>> The responsibility for the logging format should not lie with the
>>> individual model objects.
>>> From our discussion on QPID-2780 this doesn't seem like the same
>>> approach you are now taking, what changed?
>>> The change suggested by the patch on QPID-2835 will introduce
>>> inconsistency in the operation logging. Something that its
>>> introduction was designed to reduce.
>>> The LogActors are that point where the consistency is gained.
>>> By locating the LogFormat and the string builder in one location the
>>> LogActor has full responsibility of formatting log messages.
>>> The approach that I would have taken here is to expose the required
>>> common methods for logging on our Session and Connection models. This
>>> would then mean that we would have two clean interfaces boundaries:
>>> LogActors <-> Logging Framework
>>> LogActors <-> Model Objects
>>> This would mean that the desire to move to slf4j would be a matter of
>>> adjusting the Logging Framework and the adding consistent 1-0 logging
>>> would be simply a matter of implementing the model interfaces.
>>> The only code that I would expect to see added to the 0-10 Connection
>>> code paths is the introduction of Logging commands. The 0-10 Model
>>> Objects should have nothing to do with formatting logging statements.
>>> Cheers
>>> Martin
>>> On 31 August 2010 12:18, Sorin Suciu (JIRA)
>>> <qpid-dev@incubator.apache.org> wrote:
>>>>     [ https://issues.apache.org/jira/browse/QPID-2835?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
>>>> Sorin Suciu updated QPID-2835:
>>>> ------------------------------
>>>>    Attachment: qpid-2835.patch
>>>>> Implement connections (CON) operational logging on 0-10
>>>>> -------------------------------------------------------
>>>>>                 Key: QPID-2835
>>>>>                 URL: https://issues.apache.org/jira/browse/QPID-2835
>>>>>             Project: Qpid
>>>>>          Issue Type: Improvement
>>>>>          Components: Java Broker
>>>>>    Affects Versions: 0.7
>>>>>            Reporter: Sorin Suciu
>>>>>            Priority: Minor
>>>>>             Fix For: 0.7
>>>>>         Attachments: qpid-2835.patch
>>>>> This is part of the Qpid-2801, dealing with connection operational logging
on 0-10 code path.
>>>> --
>>>> This message is automatically generated by JIRA.
>>>> -
>>>> You can reply to this email to add a comment to the issue online.
>>>> ---------------------------------------------------------------------
>>>> Apache Qpid - AMQP Messaging Implementation
>>>> Project:      http://qpid.apache.org
>>>> Use/Interact: mailto:dev-subscribe@qpid.apache.org
>>> --
>>> Martin Ritchie
>>> ---------------------------------------------------------------------
>>> Apache Qpid - AMQP Messaging Implementation
>>> Project:      http://qpid.apache.org
>>> Use/Interact: mailto:dev-subscribe@qpid.apache.org
>> --
>> Sorin S
>> ---------------------------------------------------------------------
>> Apache Qpid - AMQP Messaging Implementation
>> Project:      http://qpid.apache.org
>> Use/Interact: mailto:dev-subscribe@qpid.apache.org
> --
> Martin Ritchie
> ---------------------------------------------------------------------
> Apache Qpid - AMQP Messaging Implementation
> Project:      http://qpid.apache.org
> Use/Interact: mailto:dev-subscribe@qpid.apache.org

Sorin S

Apache Qpid - AMQP Messaging Implementation
Project:      http://qpid.apache.org
Use/Interact: mailto:dev-subscribe@qpid.apache.org

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