Databases Reference
In-Depth Information
ible to the final user, while non accessible elements containing accessible ones
are renamed as
AccessDenied
elements [13].
As a support for the proposal, experimental results are presented demon-
strating the eciency gain due to static analysis with respect to run-time
analysis proposed by other approaches.
Example 4.
Consider the DTD and the XML document in Fig. 1 and suppose
that there are three user-groups:
BankEmployee
, which are employees of the
considered bank institute,
StatisticalAnalyst
, which are bank employees
who make statistics about clients and their operations, and
Client
, which are
people having a bank account at the institute.
Consider a set of authorizations stating that the members of the
BankEmployee
group can access the whole content of the
account operation
element, members of the
StatisticalAnalyst
group can access the content of
the
account operation
element but the
notes
elements, and each client can
access the
account operation
elements about their bank account. Formally,
these authorizations can be expressed as follows.
•
group:
BankEmployee
,
/account operation
,+
read
, recursive
•
group:
StatisticalAnalyst
,
/account operation
,+
read
, recursive
•
group:
StatisticalAnalyst
,
//notes
,-
read
, recursive
•
group:
Client
,
/account operation[./@bankAccN=$userAcc]
,+
read
,
recursive
We first define the schema automaton corresponding to the considered
DTD. It is first necessary to define two sets of symbols, representing elements
and attributes, respectively.
Σ
E
=
{
account operation
,
request
,
operation
,
date
,
means
,
notes
,
type
,
amount
,
recipient
,
value
}
Σ
A
=
}
Given
Σ
E
and
Σ
A
, it is now possible to define the schema automaton
M
G
as
follows.
{
@bankAccN
,
@Id
,
@number
Ω
=
Σ
E
Σ
A
•
∪
•
Q
=
Account Operation, Request, Operation, Date, Means, Notes, Type,
Amount, Recipient, Value
{
q
init
q
fin
}∪{
}∪{
}
Q
init
=
q
init
•
{
}
Q
fin
=
q
fin
•
{
Date, Means, Notes, Type, Amount, Recipient, Value
}∪{
}
δ
(
q
init
,
account operation
)=Account Operation
δ
(Account Operation,
request
)=Request
δ
(Account Operation,
operation
)=Operation
δ
(Request,
date
)=Date
δ
(Request,
means
)=Means
δ
(Request,
notes
)=Notes
δ
(Operation,
type
)=Type
δ
(Operation,
amount
)=Amount;
•
