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A Part is the basic building block of a sembleWare™
business system. A Part usually represents some form of business entity, such
as a Customer, an Invoice, a Transaction or a Product Item. Parts can also be
made up of other parts, for example an Invoice may contain within it a
collection of Line-Item Parts. In this case the Invoice is called a composite
Part.
Each Part contains definitions of how it should appear on the screen to a
user, what business rules apply, and how it is structured within a database. In
essence, a Part spans the presentation layer, application layer and
database layer in a multi-tiered system.
Most importantly, a Part specifies how it interacts with other Parts, by
defining Relationships. For example, in business an invoice is
incomplete without a customer. So in a system of invoices, the
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Invoice Part would typically state that it has a relationship with a Customer Part. It does
not actually specify the Customer Part, but instead has a holder for the
customer. This holder has "shape", in other words, fields and actions
that must be present on a Customer Part if it is to be "snapped" into the
holder.
In this way, an Invoice Part can be created with screens, rules and structure,
all of which in some way references a customer, but without the Invoice having
to know what customer Part will ultimately be used in the application. Also,
the customer Part has no knowledge of the Invoice, and could be equally used in
a system such as CRM (Customer Relationship Management) where no invoices
exist. This one-sided relationship concept is fundamental to sembleWare™
and is result in maximum re-use potential for Parts.
In sembleWare Visual Welder™, Parts are implemented as standard Microsoft
Visual Studio files. The screen definitions are regular .aspx and .aspx.vb
files, and the business rules are coded in regular .vb class files.
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