Re: Migrating from EOF to Cayenne
Re: Migrating from EOF to Cayenne
- Subject: Re: Migrating from EOF to Cayenne
- From: Chuck Hill <email@hidden>
- Date: Wed, 11 Jul 2012 11:35:48 -0700
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@hidden>
>> To: WebObjects-Dev Mailing List List <email@hidden>
>> Subject: Migrating from EOF to Cayenne
>> Message-ID:
>>
>> <CAOUwSGtOwEayxK4im97HucAUANo=email@hidden>
>> 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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--
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.
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