Im sorry I added clouds to the conversation for you. I really didn't intended to; and I was kind of hoping you would ignore the other comments that dealt with the "graph" stuff.
Ok. I'll try to explain it, and then, I figure someone who knows more will jump in and clean up the mess I cause :O)
To me a transfer object is a light version of a bean. A bean has a bunch of properties with getter and setter methods - once passed around it is both readable and writable by using the getter and setter methods. A bean might also have some validation routine(s) within it.
A transfer object on the other hand should be treated as readonly once it has been initialized. It doesn't carry around any setters or any validation logic at all - it just carries around data. Basically, it is a readonly STRUCT with a specific definition (you can't add new keys to it once it's instantiated).
Serializable in the simplest terms is kind of like converting an object into a string in such a way that the process can be reveresed so that the string can be deserialized back into its originating object form.
A mutable object has components/properties that can be modified (via set accessors) once the object has been created (mutation) Therefore a bean is mutable, a TO is not.
Hope that helps
Bill
On Apr 1, 2005 3:45 AM, Mike Kear <[EMAIL PROTECTED]> wrote:
On Apr 1, 2005 2:32 AM, Bill Rawlinson <[EMAIL PROTECTED]> wrote:
> Paul,
>
> Maybe this link will help explain. It is written by someone much more
> comfortable with all patterns, it seems, than I
>
> http://www.patternscentral.com/modules.php?name=Forums&file=viewtopic&t=78#334
>
> In fact the site in general seems pretty darn useful.
>
> Bill
>
Thank you Bill, I was most interested in what a transfer object (TO)
is supposed to do as well. Your link points to a post written by
someone comfortable with patterns perhaps, but it's still gobbledegook
to me. I was feeling very encouraged that after looking at Model-Glue
I was starting to 'get' this OO stuff. Now I'm more in the dark and
depressed than I ever was.
For example, in that link, Clayton J Kovar says "I don't agree with
the generalization that VOs represent a business entity AND it's graph
of related business entities." Now either there's an 'a' missing
before the word 'graph'. In which case he's saying a VO is a graph
of some kind. Or he is misusing the apostrophe and he's saying the VO
has a graph as a property. But what does a VO (which he's renamed TOs)
have to do with graphs? Where does that come into it?
Elsewhere he talks about "accessor/mutators" and serialization (so
therefore I assume he's American which explains the desire to
bamboozle with complicated terms when simple ones would have
communicated better) What's serialization? what the hell are
accessor/mutators?
Every time I start to see a glimmer of light in this object oriented
world, I have a huge bunch of murk and glub dropped on it until it's
incomprehensible again. I beginning to think OO and CF is like
herding cats - in other words an exercise in futility.
I'm still none the wiser what the hell a transfer object is supposed
to do. Kovar says it's supposed to hold data. But that's what I
thought a bean was supposed to do.
Can anyone explain in simple terms that a mere 50+ year old Aussie who
hasn't done a degree in IT what a transfer object is supposed to do?
Cheers
Mike Kear
Windsor, NSW, Australia
Certified Advanced ColdFusion Developer
AFP Webworks
http://afpwebworks.com
ColdFusion, PHP, ASP, ASP.NET hosting from AUD$15/month
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