Real app business logic, access serialization

Question

Hi,
in our real application we have some business logic.
The bc4j examples show for example how to limit the value
of a colum between two values.
But our business logic is not limited to a so
simple case.
For us is very common that business logic involves
more (aggregate) tables.
For example consider a invoice and
the line of the invoice. These are two tables but
a business rule say that the sum of the line should
be the total column of the invoice. Moreover the
total of the invoice can't be zero. The need the
existence of the total column in invoice is required
because speed up queries and for the constraints and
we can't make it only a display value of a
query.
To avoid data corruption we have noted that access
should serialized for a invoice. Otherwise two user
can change the lines and the total can be correct in the
session but may not be correct at the end of the
two commit.
How can we obtain this in bc4j? Where should we place
the code? How to make access of the invoice serialized?
There is some documentation or code example of this?
Very thanks in advance!

Answer 1

By marking the lines entity to be composed with the invoice entity, and marking the "lock top-level entity" you can automatically achieve the serialization you're looking for using BC4J.
If anything in the invoice, or any composed children are modified, it will lock the top-level parent (invoice) before allowing the edit to proceed.
To express a rule that asserts a rule about the sum of the detail lines, write a entity-level validation rule in the invoice (parent) entity which uses the association accessor to iterate the lines and calculate the sum.