Hi,
I am trying to utilize a decorator pattern to decorate a ADO Connection and Parameter object. However, in VB6 I cannot implement the connection object. It gives me a message that it is derived from a pure interface.
Does anybody know how you can implement a decorator on any ADO object? Or, does anybody know where to find information that will help me in getting this done?
The decorator pattern is part of a Resource Pool pattern. I'm trying to create a layer that will give my clients a (cached) connection and command objects.
Thanks in advance for the time spend on this.
Grtz.©
D.
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Leon,
I have increased points to 500, as this is indeed a "hard" question. I haven't seen much use in VB of patterns in general. In fact, I've never seen any implementation of even a simple abstract factory (at least not in somebody elses code). I am just wondering how far I can take VB towards patterns.
Grtz.©
D.
> VB6 I cannot implement the connection object.
Are you attempting to pass a connection object across a process boundry? Can't do that.
Have you looked at ADO's built in ability to cache connections?. I write stateless apps that open a new connection every time the client talks to the database and find the cacheing works great.
For those unfamiliar with Decorator Patterns (including myself), here is one definition from MSDN Magazine:
Design Patterns: Solidify Your C# Application Architecture with Design Patterns
http://msdn.microsoft.com/
But Leon is right the chances you are going to get a good response in this forum used to questions like "How do I get the record count in a recordset" are quite remote. But I am prepared to be surprised.
Hi,
I am sorry for not responding to this question. It was the weekend and quite honestly, the pub is a far better place to spend it. Anyway, thanks for the responses on this question.
Dancebert, what I am trying to acomplish is different behaveiour on a certain set of operations, and attach some other operations. And yes, in time I want to marshall connection and command objects over the proces boundaries (possibly on different machines). That is, the decorated objects. I haven't actually looked real close at the caching and pooling. I will do that now.
And yes, I am aware that the average level of questions and responses are um, how to put it politically correct, not the most bright. But perhaps we will be surprised... Who knows.
Then, on a sidenote... You can sort of make it work by making a facade class, and change behaveiour on the operation you want. But this approach disrupts old code should you want to implement a resource pool. If there is interests in this, I could post sample code.
Grtz.©
D.
It is possible to pass a command object across a process boundry, but it's relatively slow. It is not possible to pass a connection object that has an active connection across a process boundry. It is possible to build apps in VB using sophisticated techniques, despite all the seemingly boneheaded parts of the langugage (have you looked at VB's error handling yet?). I wish you good luck.
Lol,
Well, as far as VB's error handling is considered... It's On Error Goto Hell. It's ackward and unpredictable, but given enough time you can make use of it.
As far as the sophisticated stuff goes, I've already got a few app's running that implement a Repository Pattern. I'm just moving up to more complex and generic solutions. And quite honestly, this is the first real "limit" I encouter in VB. That is, VB 6. As far as I'm concerned, can't wait till I move on to .Net.
Now, what about this question. Shall I leave it open for a set amount of time?
Grtz.©
D.
It's not clear to me that the decorator pattern was to work within a process, across a process boundry or both. daffyduck14mil stated something that I interpreted to mean he wished to use it both within and across a process boundry:
>And yes, in time I want to marshall connection and command
>objects over the proces boundaries
Well, I posted that one cannot marshall an active connection across a process boundry. So, daffyduck14mil found out that part of what he wants to do is not possible. According to EE guidelines, 'you can't do that' is a legitimate answer.
What do ya'll think?
Hi,
I still think that this question is not answered. A possible future problem (that has been correctly pointed to) does not deal with the original question. That is the implementation of a decorater pattern on a connection object in VB 6. If we were to accept the comment as an answer, subsequent searches on the subject results in incorrect information.
I am very happy to give points because I did get usefull information, but I don't feel that it is a solution to the problem given. I am sure we can work out something here.
Grtz.©
D.
Closed, 500 points refunded. I PAQed this as an interesting discussion. I don't think the entire question was addressed by "you can't do that."
daffyduck14mil, you might consider creating a "Points for" question if you received useful information. Thanks all.
Lunchy
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by: leonstrykerPosted on 2004-02-06 at 04:22:57ID: 10289234
I never seen this used and only skimmed it as a topic in some books. You should consider adding points to this question as it will falll into the "the question is hard" category.
Leon