1. WEBIST 2005 – International Conference on Web Information Systems and Technologies
Efficient Management Of Multi-Version XML Documents For E-Government Applications
Federica Mandreoli
Riccardo Martoglia
Università degli Studi di Modena e Reggio Emilia
Fabio Grandi
Maria Rita Scalas
Università degli Studi di Bologna

2. Overview
Our research activities concern the implementation of Web information systems for e-Government applications
Importance of E-government:
European commission e-government
U.S. president’s e-government initiatives
More and more resources and services are being made available by Public Administrations (PAs)
We make use of temporal database and semantic Web techniques to provide improved access to such resources and services
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

3. Importance of versioning
Temporal concerns are ubiquitous in the law domain
Each normative text changes in time due to different modifications, but keeps its identity
The ability to model temporal dimensions is essential for the management of evolving norms
it is crucial to reconstruct the consolidated version of a norm
also past versions are still important
Original normative text 1 2
new version 3
new version
time
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

4. Importance of versioning
Applicability (semantic) versioning also plays an important role
some norms or some of their parts have or acquire a limited applicability
personalized version of the norm
A version only containing articles which are applicable to a citizen personal case
Self-employed
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

5. Objectives Development of an effective and efficient system where:
norms are represented as XML documents and are available on the Web
dynamics of norms in time is captured
limited applicability of norms (and their parts) is captured
Enable citizens to access personalized versions of multiversion resources
Improve and optimize the involvement of citizens in the e-Governance process
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

6. Approach Definition of a temporal XML model including
a temporal XML schema
temporal manipulation operations
applicability (semantic) extensions
Design, implementation and evaluation of system prototypes supporting the model
First system, based on “stratum” approach on top of a commercial DBMS
Ongoing research: second system, “native” approach
includes semantic annotations in multiversioning
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

7. The temporal XML data model
XML Schema based
Based on the hierarchical organization of normative texts
contents-section-article-paragraph
At each level of the hierarchy, the history of changes is represented by the versions produced
The temporal pertinence is represented by timestamps, i.e. temporal elements encoded as multiple 3-dim intervals (TA)
A reference to the modifying (active) norm is added (an_ref)
Supports ancestor-descendant inheritance
Timestamps of a node are inherited by its descendants
Along the hierarchy, redefinitions can only involve a restriction of the temporal pertinence
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

8. The temporal XML schema
Law
Num – R
Type – R
4 Temporal Dimensions:
Publication time
time of publication on the Official Journal
Validity time
time the norm is in force
Efficacy time
time the norm can be applied
Transaction time
time the norm is stored in the system
Publication – R
Vt_Start – R
Vt_End – O
Tt_Start – R
Tt_End – O
Et_Start – R
Et_End – O
Title
Contents
Vt_Start – R
Vt_End – O
Tt_Start – R
Tt_End – O
Et_Start – R
Et_End – O TA
An_ref – O
Ver
Num – R
Section
Num – R
Vt_Start – R
Vt_End – O
Tt_Start – R
Tt_End – O
Et_Start – R
Et_End – O TA
An_ref – O
Ver
Num – R
Num – R
Heading
Article
Vt_Start – R
Vt_End – O
Tt_Start – R
Tt_End – O
Et_Start – R
Et_End – O TA
An_ref – O
Ver
Num – R
Heading
Paragraph
Num – R
Vt_Start – R
Vt_End – O
Tt_Start – R
Tt_End – O
Et_Start – R
Et_End – O TA
An_ref – O
Ver
Num – R
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

9. An example document <norm num="2624/1999" type="Law">
<title>Cereals Importation</title>
<contents publication=" " vt_start=" " tt_start=" " et_start=" " > …
<article num="1">
<ver num="1"> <ta/ vt_start=" " tt_start=" " tt_end=" "
et_start=" " >
<ta/ vt_start=" " et_start=" " et_end=" " … > <ta/ vt_start=" " vt_end=" " et_start=" " … >
<paragraph num="1"><ver num="1" > …Art. 1 before modification… </ver>
</paragraph> …
</ver>
<ver num="2" an_ref="LD135/2000" > <ta/ vt_start=" " tt_start=" " et_start=" " >
<paragraph num="1"><ver num="1"> …Art. 1 after modification… </ver> </paragraph>
<paragraph num ="2"><ver num="1"> …Art. 1 after modification… </ver>
</paragraph>
</article>
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

10. “Stratum” approach Based on two components: XML document management
facilities offered by Oracle 9i
document-size granularity
structural and textual
constraints
software stratum built on top
temporal aspects
reconstruction
Extensive experimental results on the system behaviour show:
good performance
ability to manage large collections of
XML multi-version documents
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

11. Querying and modification aspects
Full search and reconstruction functionalities
FOR $a IN path WHERE constraints on $a RETURN const-tree(document($a), temporal specs)
constraints can contain keyword-based text selections
const-tree
operator for the reconstruction of a temporally consistent normative act (involves temporal selections)
temporal specs may require a temporal predicate for each of the supported dimensions
Two basic operators for the management of norm modifications:
change the textual content of a norm portion
deletion, introduction, replacement of (a part of) the norm
modifications to the temporal pertinence of a given version
time extension or suspension of (part of) the norm
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

12. Example of reconstruction (curr. ver.)
<norm num="2624/1999" type="Law">
<title>Cereals Importation</title>
<contents publication=" " vt_start=" " tt_start=" " et_start=" " > …
<article num="1">
<ver num="1"> <ta/ vt_start=" " tt_start=" " tt_end=" "
et_start=" " > <ta/ … > <ta/ … >
<paragraph num="1"><ver num="1" > …Art. 1 before modification… </ver>
</paragraph> …
</ver>
<ver num="2" an_ref="LD135/2000" > <ta/ vt_start=" " tt_start=" " et_start=" " >
<paragraph num="1"><ver num="1"> …Art. 1 after modification… <ver> </paragraph>
<paragraph num ="2"><ver num="1"> …Art. 1 after modification… </ver>
</paragraph>
</article>
( NOT INCLUDED )
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

13. “Native” approach Based on a Temporal XML Query Processor:
provides all the temporal, structural,
textual and applicability query
facilities in a single component
exploits ad-hoc data structures and
algorithms
finer “tuple” granularity
embedded “light” DBMS libraries
structural joins algorithms
allows users to store and
reconstruct on-the-fly XML norm
texts satisfying the four types of
constraints
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

14. Semantic versioning
Extension of the multi-version model based on temporal dimensions to include a semantic versioning dimension
Aim: provide personalized access to norm texts
Civic ontology a classification of citizens based on the distinctions introduced by successive norms (founding acts) that imply some limitations in their applicability
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

15. Semantic versioning
At this stage of the project, we manage “tree-like” ontologies
class taxonomies induced by the IS-A relationship
we exploit the pre-order and post-order properties of trees
New versioning dimension
Applicability of different parts of a norm text to the relevant classes of the civic ontology
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

16. Semantic versioning
Applicability is inherited by descendant nodes unless locally redefined
By means of redefinitions we can also introduce, for each part of a document, complex applicability properties
Extensions with respect to ancestors
Restrictions with respect to ancestors
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

17. Example of full search John Smith is a self-employed citizen.
He is interested in the text of all the norms ...
... which contain paragraphs dealing with health care, ...
... which were valid and in effect between 2002 and 2004, ...
... and which are applicable to his class.
Structural constraint
Textual constraint
Temporal constraint
Applicability constraint
4 orthogonal constraints
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

18. Example of full search Structural constraint Textual constraint
FOR $a IN norm
WHERE textConstr ($a//paragraph//text(), ’health AND care’)
AND tempConstr (’vTime OVERLAPS PERIOD(’ ’,’ ’)’)
AND tempConstr (’eTime OVERLAPS PERIOD(’ ’,’ ’)’)
AND applConstr (’class 7’)
RETURN $a
Structural constraint
Textual constraint
Temporal constraint
Applicability constraint
4 orthogonal constraints
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

19. Finer storing granularity
Each document is split into ad-hoc structures (tuples), providing a finer granularity and optimized time and space requirements
Tuple ( id, )
< structural attributes >
< temporal attributes >
< text >
< appicability attributes >
Each constraint is verified at query time on the respective attributes
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

20. structural attributes applicability attributes
Finer storing granularity ID
structural attributes
temporal attributes
text
applicability attributes … 4
level
startPos
Health care …
text 3 AA
15/12/1979 UC
20/12/1979 F
01/01/1980 pt
ttEnd
ttStart
etEnd
etStart
vtEnd
vtStart
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

21. norm//paragraph//text()
Example of full search
Civic ontology
Normative DB
Norm
Article 1
Article 2 TA
Ver 1
AA=3
Par 1
Par 2 …
norm//paragraph//text() TA TA
Ver 1 TA
Ver 2
Ver 1
AA=4
‘class 7’ …
AA=3,8 AA
Health care…
…text X
Health care…
…text Y
Health care…
…text Z
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

22. “Native” approach benefits
The native approach is able to access and retrieve only the strictly necessary data
ad-hoc and temporally-enhanced structures are queried
finer granularity than the entire documents managed by standard XML engines
Only the parts which are required and which satisfy the temporal constraints are used for the reconstruction of the retrieved documents
There is no need to retrieve whole XML documents and build space-consuming structures such as DOM trees, as required in the stratum approach
Enhanced query processing efficiency
Reduced memory requirements
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

23. Evaluation benchmark Three XML document sets Variable document size
5000 documents (120MB)
10000 documents (240MB)
20000 documents (480MB)
Variable document size
min = 2KB
avg = 24KB
max = 125KB
Five different query types
Queries on keywords (structural + textual constraints)
Q1 – keywords in contents
Q2 – keywords in type and contents
Temporal queries (structural + temporal constraints)
Q3 – conditions on publication, validity and transaction time
Mixed queries (structural + textual + temporal constraints)
Q4, Q5 – with keywords and temporal conditions
Five variants with personalized access
Qx-A – with additional applicability constraints
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

24. Performance evaluation
The selectivity of the query predicates strongly influences the performance of the stratum approach
Q2, Q3: large amounts of documents containing some (typically small) relevant portions have to be retrieved
The native approach shows to be faster and more reliable performance in all cases
Retrieval of useless document parts is avoided
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

25. Performance evaluation
Very high personalization query efficiency
The system is able to solve personalization problems by means of simple comparisons involving pre-post encodings
0.5-1% more time than for the original versions
3-4% storage space overhead
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

26. Performance evaluation
time
1741 msec
1366 msec
1046 msec
5000 docs
10000 docs
20000 docs
Scalability tests
The computing time grows sublinearly with the number of documents
Good scalability of the system in every type of query context
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

27. Conclusions
We presented our research work concerning the design and implementation of efficient Web-based information systems for e-Government applications
We developed a platform (“stratum” approach) for temporal management of multi-version norm texts on top of a commercial DBMS
We migrated such a system towards a more efficient platform (“native” approach) for which a specialized Temporal XML Query Processor has been designed
We implemented advanced functionalities
personalized access to resources on the basis of the digital identity of citizens
We proved our approach to be very efficient in a large set of experimental situations and showed excellent scale-up figures with varying load configurations
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications

28. Future Work Extensions of the current framework
more advanced application requirements may include a more sophisticated ontology definition
Development of a complete technological infrastructure usable in a large Web-based e-Government scenario
identification, classification and reconstruction services
Assessment of our developed systems in a concrete working environment
real users
large repository of real legal documents
WEBIST Mandreoli Martoglia Grandi Scalas - Efficient Management Of Multi-Version XML Documents For E-Government Applications