n-tier

[Mike P]

I've just started to try to create my own n-tier project, and I am using
an xsd schema to represent all my tables, and then datatables and
queries to get at my data. The question I have is, where does XML and
web services fit in to this? Do any web services go in the data layer,
and can I treat my XML exactly the same as my data coming from a
database by creating an xsd and then data tables and queries to get at
the data?

 

[Kevin Spencer]

I think I see some confusion about XML here. It is best to think of XML in
the same way that you think of HTML or any programming language. It is
simply a language, a set of semantics for creating a large variety of
entities, thousands of types in fact. It's extremely useful for creating
various kinds of data structures, but it is not useful to think of these
data structures as XML, but as what they represent. An XSD is an XML schema.
It represents the data structure of a database. A Web Service is a service
that uses the SOAP protocol, which employs XML, to make method calls to a
web server, and get back results. XML is involved in the process, but there
isn't any need to get into the actual XML to use the Web Service, only to
use the Web Service technology to make method calls and get back data as a
result. The fact that the data is returned in an XML SOAP packet is not
important, any more than the fact that a web page is returned as an HTML
text document, unless you want to write your SOAP packets by hand.

--
HTH,

Kevin Spencer
Microsoft MVP

Printing Components, Email Components,
FTP Client Classes, Enhanced Data Controls, much more.
DSI PrintManager, Miradyne Component Libraries:
http://www.miradyne.net

 

[sloan]

There is a layer that is what some call the "glue layer". This is the
objects (datasets is a good example) that all layers can see and use.

For example:

DataLayer creates a (strong) DataSet. Passes it up to the biz layer.
Biz Layer does a few mods on it, passes it up to the presentation layer.

You might say "Well then put it in the data layer"

Ahh. But the presentation layers should not know about nor reference the
data layer. Thus the conumdrum.


You read more at: ( and download sample code which I strongly recommend
going thru)


6/5/2006
Custom Objects and Tiered Development II // 2.0
or
5/24/2006
Custom Objects/Collections and Tiered Development
http://sholliday.spaces.live.com/blog/


I also reference a MS article at the bottom of the june blog entry.
BOAGag.asp
Read that article about 4 times thru. Then bookmark it. And when in doubt,
refer to that article again.

 

[Swap]

Hi,
you can introduce your web service in following way.

UI <- Business Layer <- Service Agent(who fetch data from database) <- Web Service <- Data Access <- Data Base

from Web service to Business layer your custom types (or say custom database entity object) will travel(which is in form of XML) (through XML Serialization).