Dan Waters
dwaters at usinternet.com
Fri Apr 6 13:52:24 CDT 2007
Jim, This is an article about Microsoft slowly letting go of VFP. It may become open-source to some extent. http://adtmag.com/article.aspx?id=20382 -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Jim Dettman Sent: Friday, April 06, 2007 12:01 PM To: 'Access Developers discussion and problem solving' Subject: Re: [AccessD] New database design for MS SQL Charlotte, This is a lot like what I work with in VFP and a framework called VMP. The Framework lets you create fully 3-tier apps breaking out the Business Rules and Data Services classes into a Business Object. The BO can be compiled separately into a COM object, so I can write a presentation tier in just about anything (Access, VFP, VB, etc). The Data Services like you describe below hides the BE data store and provides cascaded updates/deletes, constraints, etc. I'm about to undertake a major development project and am going back and forth between doing this in VFP/VMP as a full 3-tier app or sticking with the tried and true Access approach (it would be my first full 3-tier app with VFP/VMP). I've got to talk to the client a few more times to get a sense of what direction they'll be heading in the future, but I'm leaning towards VFP at the moment. Jim -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Charlotte Foust Sent: Friday, April 06, 2007 12:05 PM To: Access Developers discussion and problem solving Subject: Re: [AccessD] New database design for MS SQL Our executable installs on the client at this point in its existence, and our clients are *frequently* thick! We haven't split the business logic off to the server because there isn't always a server. When I mentioned Access, I was talking about the data store, not the front end. Our XML files have nothing to do with Access. FE is VS.Net but the app is designed to work locally (say, on a rig) or with the data store in SQL Server on a server (usually an office installation). The application has to be flexible enough to run either way and to be capable of switching between the two, if need be (they tend to move their licenses around!). Rather than creating different versions of the app for the varying environments, we simply built one that would work across the board. That may change someday, but we're still in the process of migrating our apps and our clients into the new century. LOL A dataset is a disconnected datastore, so it doesn't care where the BE is or what engine it runs in. A _recordset_ is like a query, a flat list of rows, but a dataset represents the separate sets of rows from one or more tables. A TYPED Dataset (as opposed to untyped) is a kind of class and models the details of the data structure in code. You can create them from scratch or using the built in tools to "generate" one. They then become objects in the project that our entity classes wrap, exposing only the programming methods and events we want to make available. Drop an entity on a form, and you have automatically connected the form to the datastore the entity represents, so you can program to its columns, methods, and properties as if it were a recordsource in an Access form. Charlotte Foust -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Jim Lawrence Sent: Friday, April 06, 2007 3:34 AM To: 'Access Developers discussion and problem solving' Subject: Re: [AccessD] New database design for MS SQL Hi Charlotte: I will comment inline -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Charlotte Foust Sent: Thursday, April 05, 2007 2:46 PM To: Access Developers discussion and problem solving Subject: Re: [AccessD] New database design for MS SQL No white papers. We started rolling our own and called in a consulting firm to review the fledgling solution and point out deficiencies. They did admit when they came back for a later review that they'd never seen a Win-based .Net app this large and complex, but we aren't ready (maybe I should say our clients aren't ready) to convert totally to web-based yet. Comment: Sounds very impressive. We're using either SQL 2005 or Access 2000 format BE because some of our clients are on drilling rigs in the middle of the ocean and don't have SQL Server handy. The embedded SQL for the provider adapters is stored in XML files and we read it in using a streamreader and pass it back to the calling data provider routine. The only business logic on the server is in cascading updates and deletes, etc., nothing else except relationships at this point because we still have to handle both SQL Server and Access back ends. The business logic is in its own assembly that's part of the overall solution. Not sure what you mean by a desktop design. Comment: 'Desktop design' is my description of an application that has it core functionality supported at the client end; or win-based or thick client (this could also be describing the actual client?) ...As opposed to thin client application where most of my work seems to be migrating. We create and supply software to the drilling industry--oil, gas, geothermal--so a well is a hole in the ground plus everything associated with that. A wellbore, is the hole itself, which may be the original hole in the ground or a sidetrack drilled as an offshoot of another wellbore. Comment: A very good explanation of your business. I would be interested in how the data tier actually works or maybe just an overview ...without divulging any trade secrets of course... like how the data tier layer abstracts the actual data structures. Is your office using the XML option in .Net datasets, through classes to connect via an OLE (third party?) to the actual tables being either MDB or MS SQL? (Handling XML in MS SQL 2005 is built-in but I was unaware that Access had the same capabilities.) I am not interested in specifics just the concepts... Maybe a bird's-eye view? Charlotte Foust MTIA Jim -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com