Hi,

For example when you form is not always the same and depend on two
variable a webservice send you an Xml file with the field that you want
and you can bind it to infopath.
For your scenario your description is a little bit general .

++

Here are some reasons for not directly connecting to a database:

1) Your form users do not have rights to the database directly.
2) Your database is behind a firewall which only allows port 80 traffic.
3) There are design differences between your form schema and your database
tables. For instance, your form allows entry on ONE master row and multiple
detail rows in a typical master-detail table setup.
4) You have business rules which cannot be conveniently expressed in JScript
or TSQL.

I have found all four reasons to be applicable for every Infopath project I
have done so far.

Also, since you talk about design in general, here is how I design my
Infopath solutions. I start with one or more XML schemas (schema? schemae) ,
which I use both as the basis of my Infopath forms, as well as to create
typed datasets, which I then use in web services to receive data from those
forms. I often have multiple forms based on the same schema, with diffrent
read-write rules and submission points. This has helped me create
workflow-type solutions without too many client-side rules or script.