Re: Advice on Architecture
From: Andrew (Andrew_at_discussions.microsoft.com)
Date: 07/23/04
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Date: Fri, 23 Jul 2004 03:16:02 -0700
Nick,
Many thanks, the basic data will be uploaded at start up with additional data be upload upon demand but still infrequently. The only exception will be a realtime price feed from Bloomberg which will cause the recalcution of some data presented in the GUI. The realtime feed I may limit to every five minutes and will be accessed via a COM component.
I do like the advantages of datasets, but feel the remove much of the OOP from a design. I also feel they limit reuse, but I guess it speed up development as well.
"Nick Malik" wrote:
> You mention that you will read the data... you don't say how often.
> However, in general, the dataset object was created as a disconnected
> abstraction from the database. The methods on the dataset are VERY useful
> for doing all sorts of tasks, from filling user interfaces, to querying on
> subsets. It can be serialized across physical tiers, (which has it's
> advantages on occasion but should be used carefully). It is a very good
> object, that is a bit expensive to fill. If you aren't filling your
> datasets every half-second, this is the way to go.
>
> My recommendation: for all your lookup data (used to populate drop downs):
> create a stored proc that returns every static lookup query under 1000
> records as a series of individual SELECT statements all in one call. You
> can load it up once, in a single dataset, and assign individual tables from
> that to your GUI.
>
> If you need to do a lookup against a dynamic table (list of customers) for
> the sake of a dropdown, a generalized collection of rows will work. You
> don't need to move the data from the DataRow that comes back from the Data
> Reader. You can simply store the array of DataRow objects and pass it
> around.
>
> If you are going to make a connection, get data, fill some GUI, and not
> update the database, and ever time you perform this operation, you will do
> the exact same process again, always connecting, the SERIOUSLY consider
> using the DataReader. It is a good bit faster than a DataSet without the
> memory overhead. If you aren't going to use the capabilities of the
> DataSet, it can be a waste of effort to fill it.
>
> An excellent article to shed more light is:
> http://msdn.microsoft.com/msdnmag/issues/04/06/DataPoints/default.aspx
>
> Of course, if you want your DAL to always work in one way, and not two ways
> (as I suggested), then you can create a Facade pattern object that embeds
> either a DataSet or an array of DataRow objects, depending on the
> constructor. You can then provide a single interface to your code, and only
> allow the object itself know how the data representation in your code
> actually manages the data. (That's the design tip).
>
> I hope this helps,
> --- Nick
>
> "Andrew" <Andrew@discussions.microsoft.com> wrote in message
> news:5C97FD34-C6BC-4090-9164-D20D7821617F@microsoft.com...
> > I am starting my first C# project and have a design issue which I would
> appreciate some advice about. I am wondering whether to use dataset to pass
> information between components or if I should implement components and
> collections. I wondered what the advantages and disadvantages of both
> approaches were in .NET. I am at the start of the project and would like to
> make the right decision. My last project was VB and MTS and we used
> recordsets as a means of passing data between tiers. It has disadvantages
> but the filtering and sorting facilities were very useful.
> >
> > The project will feature a rich GUI with drag and drop, a SQL server back
> end, plus real time access to Bloomberg, it will be mostly readonly database
> access and I am not expecting to update any database data.
> >
> > Any advice gratefully received.
>
>
>
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