Rights and Intentions in Value Modeling - Intentional Perspectives on Information Systems Engineering - page 205

Fig. 8 Bookshop example
with custody
given in Fig. 7, which shows that a customer can file an insurance claim (plead a
claim) and receive a reimbursement (ownership of money).
Guideline 3 : For each value exchange of goods, introduce optionally an arrow
representing custody provision.
A simple example of applying this guideline is shown in Fig. 8, which extends
Fig. 6, showing that a book is physically transported to the customer, thereby giving
her custody of it.
Guideline 4 : For each value exchange, introduce optionally an arrow representing
evidence provision.
An evidence document should typically be introduced in a value exchange if the
rights that it certifies cannot be proven without showing the document. In some cases
it is enough to be the bearer of an evidence document to be eligible to access the
rights the document refers to, but in some cases these rights are personal and only
hold for the person specified in the document. Only in the former case should the
evidence document be included in the value model. In the next section an example
where evidence documents are used in the model is introduced.
4.2 The Pawnshop Example
The following example illustrates how to analyze and model a business case using
the notation and guidelines proposed above. The business case chosen is that of a
pawnshop, which lends money to borrowers on a short-term basis accepting goods
as collateral. A pawnshop and a borrower can make business according to a number
of value exchanges, in Fig. 9 shown in two different pairs of value interfaces. The
first one is when the borrower gets a time limited right to use the money and pays an
interest; this is the case where the borrower returns the money and gets the collateral
back. The second pair of value interfaces models when the borrower gets ownership
of the money and the pawnshop gets ownership of goods, i.e. the collateral; this is
the case where the borrower does not return the money and the pawnshop takes the
collateral. The diagram also shows that the pawnshop may sell goods to buyers.
The value model of Fig. 9 represents the business case of a pawnshop only par-
tially as it focuses on transfers of ownership, e.g. the role of collaterals is not made
explicit. In order to arrive at a richer value model showing a more complete picture