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Posted to users@wicket.apache.org by Kent Tong <ke...@cpttm.org.mo> on 2010/06/19 13:23:32 UTC
Getting started with Scala, Spring, Hibernate & Wicket
Hi,
I've written a tutorial on this topic. You may check it out at
http://www.dzone.com/links/getting_started_with_scala_spring_hibernate_wicket.html
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by Brian Topping <to...@codehaus.org>.
On Jun 19, 2010, at 12:05 PM, James Carman wrote:
> On Sat, Jun 19, 2010 at 11:54 AM, Brian Topping <br...@gmail.com> wrote:
>> The best reason for me to keep a service/business layer talking to the DAO is to provide a clean transactional boundary. Then, all I have to do is add a Spring @Transactional annotation to the method and I'm fully atomic.
>>
>> If my view logic is calling a half dozen DAO methods to effect an update, there's no way to have a single method demarcate the transaction. Without a single method, no use of @Transactional, and I have to maintain complex transactional code by hand. This is way more error prone and complex than taking (what are admittedly attractive) shortcuts to remove the service layer.
>>
>
> You can also annotate your Wicket pages/components methods with the
> @Transactional annotation if you use the AspectJ compiler. They have
> to be public or protected in order for the compiler to pick them up
> and weave them I believe. No big deal, in practice, really.
Sure, but AspectJ can be a machine gun in the hands of babes. I try to avoid requiring team members be that qualified just to work on basic code. Because once something like AspectJ is in the source base, it starts getting used, and before you know it, you have to start making solid experience with this new esoterica a hiring requirement. Too expensive.
>
>> As a bonus, with well-defined service layer interfaces, I can easily generate SOAP or REST interfaces and expose them to other fat clients like mobile devices in the future.
>>
>
> Agreed, but having one method that merely delegates to another is just
> plain silly, IMHO. You'd probably generate custom services that are
> tailored to the different view implementations so that you can
> aggregate things correctly for optimization purposes.
It's a pattern, and sticking with one pattern is very smart. Especially because very few screens in a reasonably valuable application are only going to call a single DAO method. It happens, but I'd question the value of the app at that point, and whether it needs transactions at all. In that case, you are right, kill the service layer.
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by James Carman <ja...@carmanconsulting.com>.
On Sat, Jun 19, 2010 at 11:54 AM, Brian Topping <br...@gmail.com> wrote:
> The best reason for me to keep a service/business layer talking to the DAO is to provide a clean transactional boundary. Then, all I have to do is add a Spring @Transactional annotation to the method and I'm fully atomic.
>
> If my view logic is calling a half dozen DAO methods to effect an update, there's no way to have a single method demarcate the transaction. Without a single method, no use of @Transactional, and I have to maintain complex transactional code by hand. This is way more error prone and complex than taking (what are admittedly attractive) shortcuts to remove the service layer.
>
You can also annotate your Wicket pages/components methods with the
@Transactional annotation if you use the AspectJ compiler. They have
to be public or protected in order for the compiler to pick them up
and weave them I believe. No big deal, in practice, really.
> As a bonus, with well-defined service layer interfaces, I can easily generate SOAP or REST interfaces and expose them to other fat clients like mobile devices in the future.
>
Agreed, but having one method that merely delegates to another is just
plain silly, IMHO. You'd probably generate custom services that are
tailored to the different view implementations so that you can
aggregate things correctly for optimization purposes.
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by Brian Topping <br...@gmail.com>.
The best reason for me to keep a service/business layer talking to the DAO is to provide a clean transactional boundary. Then, all I have to do is add a Spring @Transactional annotation to the method and I'm fully atomic.
If my view logic is calling a half dozen DAO methods to effect an update, there's no way to have a single method demarcate the transaction. Without a single method, no use of @Transactional, and I have to maintain complex transactional code by hand. This is way more error prone and complex than taking (what are admittedly attractive) shortcuts to remove the service layer.
As a bonus, with well-defined service layer interfaces, I can easily generate SOAP or REST interfaces and expose them to other fat clients like mobile devices in the future.
On Jun 19, 2010, at 8:07 AM, James Carman wrote:
> Why do you have page -> service -> dao? Why not just talk directly to
> the DAO for the getAll() method. This level of indirection just
> causes more code (and confusion) in your simple example. Is this just
> a "best practice" that you've devised? I've never really understood
> folks' aversion to talking to the DAOs from the view layer, especially
> when it means you have to have duplicate methods in your service layer
> to do so. It just doesn't make sense to me.
>
>
> On Sat, Jun 19, 2010 at 8:01 AM, James Carman
> <ja...@carmanconsulting.com> wrote:
>> Why is spring-orm version 3.0.1.RELEASE and not 3.0.3.RELEASE? Why
>> not just uset a {spring.version} property in your POM so that it all
>> stays in synch?
>>
>> On Sat, Jun 19, 2010 at 7:23 AM, Kent Tong <ke...@cpttm.org.mo> wrote:
>>> Hi,
>>>
>>> I've written a tutorial on this topic. You may check it out at
>>> http://www.dzone.com/links/getting_started_with_scala_spring_hibernate_wicket.html
>>>
>>>
>>>
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
>>> For additional commands, e-mail: users-help@wicket.apache.org
>>>
>>>
>>
>
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>
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RE: Getting started with Scala, Spring, Hibernate & Wicket
Posted by Tim L Casey <tc...@cataphora.com>.
The reaction comes from years of watching UI centric people, who have a
different design goal, use dao code poorly; and then watching dao type
people use UI code poorly.
I guess I view the layering as inevitable. Even if it is as simple as
moving a tag, I am not sure I want anyone to have that choice.
-----Original Message-----
From: jcarman@carmanconsulting.com [mailto:jcarman@carmanconsulting.com] On
Behalf Of James Carman
Sent: Saturday, June 19, 2010 9:12 AM
To: users@wicket.apache.org; tim.casey@cataphora.com
Subject: Re: Getting started with Scala, Spring, Hibernate & Wicket
On Sat, Jun 19, 2010 at 12:06 PM, Tim L Casey <tc...@cataphora.com> wrote:
>
>
> Thats ok. I never understood folks who dont use layers.
>
I do use layers, when it makes sense. It's just a matter of taste, I
guess. Some folks like to stick with their paradigm no matter what.
I guess I've just become a bit more flexible when it turns out to save
me some code (like having pass-through methods just to have them). If
I need to introduce some logic in between my view/data layers later, I
can easily do so. Using services too much is a symptom of an "anemic"
domain model.
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by James Carman <ja...@carmanconsulting.com>.
On Sat, Jun 19, 2010 at 12:06 PM, Tim L Casey <tc...@cataphora.com> wrote:
>
>
> That’s ok. I never understood folks who don’t use layers.
>
I do use layers, when it makes sense. It's just a matter of taste, I
guess. Some folks like to stick with their paradigm no matter what.
I guess I've just become a bit more flexible when it turns out to save
me some code (like having pass-through methods just to have them). If
I need to introduce some logic in between my view/data layers later, I
can easily do so. Using services too much is a symptom of an "anemic"
domain model.
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RE: Getting started with Scala, Spring, Hibernate & Wicket
Posted by Tim L Casey <tc...@cataphora.com>.
Thats ok. I never understood folks who dont use layers.
-----Original Message-----
From: jcarman@carmanconsulting.com [mailto:jcarman@carmanconsulting.com] On
Behalf Of James Carman
Sent: Saturday, June 19, 2010 5:07 AM
To: users@wicket.apache.org
Subject: Re: Getting started with Scala, Spring, Hibernate & Wicket
Why do you have page -> service -> dao? Why not just talk directly to
the DAO for the getAll() method. This level of indirection just
causes more code (and confusion) in your simple example. Is this just
a "best practice" that you've devised? I've never really understood
folks' aversion to talking to the DAOs from the view layer, especially
when it means you have to have duplicate methods in your service layer
to do so. It just doesn't make sense to me.
On Sat, Jun 19, 2010 at 8:01 AM, James Carman
<ja...@carmanconsulting.com> wrote:
> Why is spring-orm version 3.0.1.RELEASE and not 3.0.3.RELEASE? Why
> not just uset a {spring.version} property in your POM so that it all
> stays in synch?
>
> On Sat, Jun 19, 2010 at 7:23 AM, Kent Tong <ke...@cpttm.org.mo> wrote:
>> Hi,
>>
>> I've written a tutorial on this topic. You may check it out at
>>
http://www.dzone.com/links/getting_started_with_scala_spring_hibernate_wicke
t.html
>>
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
>> For additional commands, e-mail: users-help@wicket.apache.org
>>
>>
>
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by James Carman <ja...@carmanconsulting.com>.
Why do you have page -> service -> dao? Why not just talk directly to
the DAO for the getAll() method. This level of indirection just
causes more code (and confusion) in your simple example. Is this just
a "best practice" that you've devised? I've never really understood
folks' aversion to talking to the DAOs from the view layer, especially
when it means you have to have duplicate methods in your service layer
to do so. It just doesn't make sense to me.
On Sat, Jun 19, 2010 at 8:01 AM, James Carman
<ja...@carmanconsulting.com> wrote:
> Why is spring-orm version 3.0.1.RELEASE and not 3.0.3.RELEASE? Why
> not just uset a {spring.version} property in your POM so that it all
> stays in synch?
>
> On Sat, Jun 19, 2010 at 7:23 AM, Kent Tong <ke...@cpttm.org.mo> wrote:
>> Hi,
>>
>> I've written a tutorial on this topic. You may check it out at
>> http://www.dzone.com/links/getting_started_with_scala_spring_hibernate_wicket.html
>>
>>
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
>> For additional commands, e-mail: users-help@wicket.apache.org
>>
>>
>
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Re: Getting started with Scala, Spring, Hibernate & Wicket
Posted by James Carman <ja...@carmanconsulting.com>.
Why is spring-orm version 3.0.1.RELEASE and not 3.0.3.RELEASE? Why
not just uset a {spring.version} property in your POM so that it all
stays in synch?
On Sat, Jun 19, 2010 at 7:23 AM, Kent Tong <ke...@cpttm.org.mo> wrote:
> Hi,
>
> I've written a tutorial on this topic. You may check it out at
> http://www.dzone.com/links/getting_started_with_scala_spring_hibernate_wicket.html
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>
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