Hi joel,

>Some have suggested using XML as the local data engine for meta data in .NET. Definitely not as good as VFP's local engine, but it can be used to eliminate calls to the server when you want to keep the data local.

I've got serious doubts if this is a good strategy. XML is a standardized way to store data, not about DML (Data Manipulation Language). Though there seem to be products which are meant to do more or less the same DML tasks to some limited level there does not seem to be anything standard in there. OTOH, you don't have much choice if you're faced with these kind of integration problems.

If you compare handling XML data with handling relational data, you'll see that in the case of XML the data is standardized and with releational data the DML is standardized (SQL). Here lies a big difference if you'd ask me. To me with data intensive apps I don't care much how the data is stored but I do care how to query and access this data in a standard and uniform way (SQL).

If you'd ask me, the performance and transparancy of handling relational data is way better than handling XML data. Take for example simple task of reordering data on a specific field: this is way faster and more straightforward with relational data than with XML. XML has serious limits when you want to use this data in the same way as you would do with relational data. For example: Handling data from large XML documents take ages to process, because it is difficult of not impossible to quickly filter a XML on a specific field value. This is because a "record" does not have the possibility of indexing or even a fixed length. This make optimization virtually imposible.

I Don't believe XML was designed for these kind of tasks. Again it is a uniform way of exchanging data, not a uniform way to efficiently query or process data. I would be nuts to build a XML DML in VFP for handling straightforward database data. Just convert the data from XML to a cursor (XMLTOCURSOR and CURSORTOXML) and process it from there (with SQL and xBase commands). You can't do this in .NET, you'll have to use more exotic and unstandardized methods to do this.

IOW: IMO using XML extensively in .NET applications, just because of the lack of a local dataengine might be the biggest trap for .NET developers to fall in. It can become one of the major design mistakes of your ambitious projects in the long run: You're trying to workarround a problem that shouldn't have to be a problem (with a local database engine in .NET) in the first place.

Walter,