Hi Farrukh,
Thanks for the summary!
Chuck
On 2012-07-13, at 5:06 AM, Farrukh Ijaz wrote:
> Sorry for late response, just landed last night.
>
> The idea is very simple to understand and implement. E.g. I've a third party
> library which has a method named with following signature:
>
> String encode(String someString) {
> // some crappy encoding performed on someString and saved as encoded...
> return encoded;
> }
>
> Now this method can be private, public, protected, static, final, blah blah
> etc. I find that encoding is buggy, how to fix it? There are two ways:
>
> 1. Get the source code, fix the method and submit patch. (This is sometimes
> not possible and for sure not possible in case of WebObjects)
> 2. Use AOP
>
> Forget about option 1. In Option 2 we have to use some AOP mechanism and the
> one that I've tested with my Wonder apps is AspectJ. I'm not going into
> details as it's a vast subject but providing links which are sufficient to
> experiment :)
>
> http://www.eclipse.org/aspectj/
> http://www.eclipse.org/aspectj/doc/released/progguide/starting-aspectj.html#the-dynamic-join-point-model
>
> As far as weaving is concerned, I would suggest to use dynamic join point as
> they can be used to intercept calls and invoke different code rather than
> modifying the original classes.
>
> The idea is we need to define join point for the method which is buggy or
> where we want to provide our own implementation. When the code is executed,
> the class loader reroutes the request for incoming method calls to our code.
> AOP is different that OOP. In contrast with OOP where methods are associated
> with Objects, AOP is used to classify those methods under common aspects and
> normally we use regular expressions for that. Two very common aspects I can
> explain here:
>
> 1. You may have lots of methods and you want to collect execution type for
> each method call. (A logging aspect)
> 2. A developer like me who put all the code in try block and catch one super
> Exception, someone would like to perform different operations on each
> sub-exception can write an aspect to catch my exceptions and do whatever he
> wants and then continue the original processing.
>
> I'm not familiar with internals of the WebObjects but the code that's
> responsible for single thread can be studied and multithreaded solution can
> be provided using AOP. If someone is interested to work with me to on this,
> I'm more than happy to help where I can :)
>
> Farrukh
>
> On 2012-07-11, at 10:25 PM, Chuck Hill <[email protected]> wrote:
>
>> Hi Farrukh,
>>
>> I like the idea of using AOP to address bugs in WO. Can you give us any
>> details on how you did that?
>>
>> As for making EOF multi-threaded.... that is a very fundamental part of the
>> design. Fixing that with AOP would be challenging. :-)
>>
>>
>> Chuck
>>
>>
>>
>> On 2012-07-11, at 11:12 AM, Farrukh Ijaz wrote:
>>
>>> Hi,
>>>
>>> In past I've used AOP to address issues of closed source. This I believe if
>>> carefully used can help convert the EOF from single to multi threaded
>>> and/or solve other bottleneck problems. Having said this doesn't mean I'm
>>> against Cayane. However if the current EOF issues get fixed with AOP
>>> patched code would be better for those who don't want to or for some
>>> reasons can't switch to Cayane.
>>>
>>> Farrukh
>>>
>>> Chuck Hill <[email protected]> wrote:
>>>
>>>> I agree that we need to more closely examine Cayenne before jumping in
>>>> with both feet. How mature are the tools? What is the functionality gap?
>>>> How important is the missing functionality? How costly is adding any
>>>> needed functionality? Will the missing functionality fit in with the
>>>> Cayenne architecture? How stable is it? How well does it scale (scaling
>>>> is more than multi-threaded EOF)? And Cayenne is only EOAccess/EOControl.
>>>> What do we do about the presentation layer? Getting rid of 2/3 of WO
>>>> still leaves you with WO.
>>>>
>>>>
>>>> Chuck
>>>>
>>>> On 2012-07-11, at 11:29 AM, Theodore Petrosky wrote:
>>>>
>>>>>
>>>>> Hurray someone actually started talking about this.
>>>>>
>>>>>
>>>>> I want to add my two cents without starting a "this is better than that"
>>>>> conversation.
>>>>>
>>>>> If Cayenne is to be utilized, someone in the know must look not only at
>>>>> the current state of Cayenne, but at the developers. What is/was their
>>>>> philosophy behind what they write/wrote? If we don't, it will be a very
>>>>> short and costly marriage. Costly, because we either buck up and foot the
>>>>> bill to rewrite Webobjects or continue in a bad relationship.
>>>>>
>>>>> I am writing this not as a diatribe but because I am concerned that in
>>>>> the excitement of looking at Cayenne, the obvious impact of differing
>>>>> philosophies of the original authors may be ignored. BTW, I say original
>>>>> authors because the person that wrote the first line of code left his/her
>>>>> imprint on the direction of all code that follows.
>>>>>
>>>>> JMHO (i mean that sincerely).
>>>>>
>>>>> Ted
>>>>>
>>>>>> Message: 4
>>>>>> Date: Wed, 11 Jul 2012 10:09:08 -0500
>>>>>> From: John Huss <[email protected]>
>>>>>> To: WebObjects-Dev Mailing List List <[email protected]>
>>>>>> Subject: Migrating from EOF to Cayenne
>>>>>> Message-ID:
>>>>>>
>>>>>> <CAOUwSGtOwEayxK4im97HucAUANo=cfnrkq9ej5z+679bcd7...@mail.gmail.com>
>>>>>> Content-Type: text/plain; charset="windows-1252"
>>>>>>
>>>>>> At WOWODC there was a lot of interest in migrating from EOF
>>>>>> to Cayenne, and
>>>>>> even entirely rebasing Wonder to run on top of Cayenne
>>>>>> instead of EOF.
>>>>>>
>>>>>> *Why would anyone want to do this? *
>>>>>>
>>>>>> 1. Cayenne is open-source and is actively
>>>>>> being developed
>>>>>> 2. Cayenne has great concurrency support
>>>>>> which is in stark contrast to
>>>>>> EOF single-threaded architecture
>>>>>> 3. Cayenne is conceptually very similar to
>>>>>> EOF so the transition is
>>>>>> fairly straightforward
>>>>>>
>>>>>> For those reasons it is a much better long term solution
>>>>>> than EOF, which is
>>>>>> now frozen in time. Cayenne can be used inside a WO
>>>>>> application as an EOF
>>>>>> replacement while continuing to use the rest of WebObjects.
>>>>>>
>>>>>> *I'm interested. Now what?*
>>>>>>
>>>>>> - Learn about Cayenne. The best source of
>>>>>> information for comparing EOF
>>>>>> and Cayenne is on the
>>>>>> wiki<http://wiki.wocommunity.org/display/WO/Alternative+Technologies-Cayenne>.
>>>>>> In addition, you can look at the
>>>>>> documentation<http://cayenne.apache.org/>for
>>>>>> Cayenne.
>>>>>> - Use Cayenne in your new projects.
>>>>>> Cayenne runs just fine inside a
>>>>>> WebObjects application. Wonder has
>>>>>> the ERCayenne framework and
>>>>>> ERCayenneExample to help you get started.
>>>>>> I suggest working with the trunk
>>>>>> of the Cayenne source (and Wonder too)
>>>>>> since some things are just being
>>>>>> added to make this easier.
>>>>>> - Help work on easing and automating the
>>>>>> migration from EOF to Cayenne.
>>>>>> It is possible to automate a large part of
>>>>>> the work involved in moving from
>>>>>> EOF to Cayenne. But it requires effort.
>>>>>> ERCayenne in Wonder has a class
>>>>>> that will convert an EOModel to a Cayenne
>>>>>> model (the class is
>>>>>> CayenneConverter). This works well, but
>>>>>> could be improved. I've started
>>>>>> working on an Eclipse refactoring script
>>>>>> that will convert from one API to
>>>>>> the other. Yes, you may not have known (I
>>>>>> didn't) that Eclipse can record a
>>>>>> series of refactorings and save it as a
>>>>>> script. The bulk of the migration
>>>>>> work is creating refactoring scripts in
>>>>>> Eclipse by performing refactorings
>>>>>> on a stubbed out version of the EOF API to
>>>>>> convert the API into the
>>>>>> equivalent Cayenne API. After performing
>>>>>> the refactorings, a script can be
>>>>>> exported using Refactor->"Create
>>>>>> Script". For EOF methods that do not have
>>>>>> a direct Cayenne equivalent, helper
>>>>>> methods (or classes) will need to be
>>>>>> written that can serve as a direct
>>>>>> replacement.
>>>>>>
>>>>>> *How can I help specifically with the migration effort?*
>>>>>>
>>>>>> - CayenneConverter in ERCayenne (for
>>>>>> converting the model) does not
>>>>>> convert the connection dictionaries in the
>>>>>> EOModel yet.
>>>>>> - CayenneConverter does a poor job
>>>>>> converting fetch specs defined in the
>>>>>> model currently.
>>>>>> - We need to create new subclasses of
>>>>>> Cayenne's DbAdapter that use the
>>>>>> Wonder naming convention for primary key
>>>>>> generators/sequences. This is done
>>>>>> by subclassing classes like
>>>>>> PostgresPkGenerator and overriding
>>>>>> sequenceName. This is necessary to
>>>>>> support existing databases created with
>>>>>> EOF.
>>>>>> - An Wonder-like entity template is
>>>>>> already in ERCayenneExample. This
>>>>>> needs to be examined and any missing
>>>>>> functions from WonderEntity need to be
>>>>>> added. For example, I know some the
>>>>>> .deleteAllXXXXRelationships and
>>>>>> .createXXXX(…) methods are missing.
>>>>>> - More refactorings need to created. For
>>>>>> example, a refactoring script
>>>>>> should be made that changes NSArray and
>>>>>> NSDictionary methods to the
>>>>>> equivalent List or Map APIs (since Cayenne
>>>>>> doesn't use these classes for
>>>>>> relationships or fetch results you
>>>>>> probably want to minimize the places you
>>>>>> need them).
>>>>>> - Submit code to Cayenne or create
>>>>>> Jira<https://issues.apache.org/jira/browse/CAY>issues
>>>>>>
>>>>>> Any questions? :-)
>>>>>>
>>>>>> John
>>>>>
>>>>>
>>>>> _______________________________________________
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>>>>>
>>>>> This email sent to [email protected]
>>>>
>>>> --
>>>> Chuck Hill Senior Consultant / VP Development
>>>>
>>>> Practical WebObjects - for developers who want to increase their overall
>>>> knowledge of WebObjects or who are trying to solve specific problems.
>>>> http://www.global-village.net/gvc/practical_webobjects
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
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>>>>
>>>> This email sent to [email protected]
>>
>> --
>> Chuck Hill Senior Consultant / VP Development
>>
>> Practical WebObjects - for developers who want to increase their overall
>> knowledge of WebObjects or who are trying to solve specific problems.
>> http://www.global-village.net/gvc/practical_webobjects
>>
>>
>>
>>
>>
>>
>>
>>
>
--
Chuck Hill Senior Consultant / VP Development
Practical WebObjects - for developers who want to increase their overall
knowledge of WebObjects or who are trying to solve specific problems.
http://www.global-village.net/gvc/practical_webobjects
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