Re: Looking for a decent data access architecture to implement
- From: "Ignacio Machin \( .NET/ C# MVP \)" <ignacio.machin AT dot.state.fl.us>
- Date: Thu, 18 Aug 2005 11:05:34 -0400
Hi,
http://msdn.microsoft.com/practices/
Will give you what you want.
cheers,
--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
"Johann Blake" <johannblake@xxxxxxxxx> wrote in message
news:1124268178.977941.260690@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>I am looking for a good solution on how to implement data access in an
> application so that there is a clean separation between the data access
> layer, the business layer and the GUI layer. I am looking for a robust
> solution for a major application. Almost every developer seems to come
> up with a completely different solution. While many of them are not
> bad, I really want a very good one.
>
> My database is SQL Server 2000 and I am using Visual Studio .NET for
> application development. In the past I use to have a "data access
> layer" that I wrote in code to insulate my business logic layer from
> the actual database. The idea behind this was to make the app
> independent of the actual database since it may have been necessary to
> support different databases.
>
> That was several years ago.
>
> The problem I found with having a data access layer was that you had to
> create classes and methods that abstract the data so that it isn't
> database specific. This resulted in a lot of code creating recordsets
> and migrating the data from the business layer to the data access
> layer. Another problem with this approach is that every time you need
> to make a change to the database model you need to change the code in
> the data access layer and even the business layer (in the case of
> adding a new field to a table or deleting one). This becomes tedious.
> Furthermore, it was not possible to have data bound controls in the
> GUI. Any changes to data in a textbox or grid had to be manually
> changed in code to the underlying recordset before updating the
> database.
>
> The optimal solution that I was looking for was what ADO.NET appears to
> offer. By using DataSets and XML, it is possible to abstract the actual
> data source. In other words, the DataSet is independent of the actual
> database or data source. But I am still left with a few issues that
> seem awkward to handle.
>
> First is using a DataSet with a control so that it is data bound. If I
> bind a control to a DataSet, how is it possible to have some sort of
> intermediate checking when data is added, modified or deleted? Is there
> some event that can be trapped prior to an update so that I can inspect
> the data, possibly modify it if necessary or even cancel the update?
> How does this event fit into a business logic layer? Are these events
> specific to DataSets or the control? From what I've seen, they seem to
> short-circuit the business layer, i.e., changes in the GUI go straight
> to the DataSet. Should these data change events be considered a data
> access layer? If they are considered a data access layer, I would
> assume that the proper programming technique would be to contain these
> notification events in a class of their own separate from the GUI or
> business layer. If you've done this before, how have you implemented
> this separation.
>
> Another issue has to do with maintaining the database model. I use to
> use Visio Enterprise Architect that supports database modelling but I
> came to the conclusion after lengthy use that this tool is ill-suited
> for doing database modelling and maintenance. It really is a band-aid.
> A better tool might be Rational Rose but currently I can't afford that.
> What I have noticed is that in Visual Studio .NET you can use Sever
> Explorer to open a database and create a diagram, which also can be
> done using SQL Server Enterprise Manager. What I like about using
> Visual Studio .NET for maintaining the database is the tight
> integration with the other tools used to create DataSets. But it isn't
> clear to me how to synchronize changes in the database to the various
> elements in my app that use the database. In other words, if I add a
> field, do I need to do a refresh somewhere to cause any currently
> existing DataSets to reflect these changes?
>
> Currently I haven't seen a decent solution on how to make a DataGrid
> bind to a DataSet that allows me to get notifications prior to record
> updates. Most of the samples I've seen posted all use code to add new
> records.
>
> I suppose what I am looking for is a solution that is cleanly separates
> the data access layer from both the GUI and business logic layer and
> where maintenance can be done as easily as possible using graphical
> tools like those and assistants. Can you give me a few hints on the
> architecture and/or method/processes you use for implementing data
> access.
>
> Any links to articles on this subject would be welcomed.
>
> Thanks
> Johann Blake
>
.
- References:
- Looking for a decent data access architecture to implement
- From: Johann Blake
- Looking for a decent data access architecture to implement
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