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Geographic XML database management system
1. Technical field
The present invention relates to an XML database management system and a da-
tabase for providing geographic information.
2. The prior art
Geographical data have an increasing importance for a number of technical appli-
cations. For example, the planning of infrastructure networks such as streets, rail-
ways, water pipes and power grids always involve questions of geography.
More and more, information technology is used to make geographical data avail-
able in a form, which by far exceeds the capabilities of a simple map. Geographic
information systems (GIS) allow linking information attributes to location data,
for example people to addresses, buildings to parcels, or streets within a network.
The available geographic information is provided in several layers allowing a
separate processing of the data but also a complete view showing relations be-
tween the various layers.
A common data format to store geographic information is a so-called shape file
which has been developed by the company ESRI in Redlands, California. A shape
file stores nontopological geometry and attribute information in a common data
set. The geometry defining spatial features for a feature is stored as a shape com-
prising a set of vector coordinates. The attribute information is typically stored as
text information.
Shape files can support point, line, and area features. Area features are represented
as closed loop, double-digitized polygons. Attributes are held in a dBASE® for-

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mat file. Each attribute record has a one-to-one relationship with the associated
shape record.
An ESRI shape file consists of a main file, an index file, and a dBASE table. The
main file is a direct access, variable-record-length file in which each record de-
scribes a shape with a list of its vertices. In the index file, each record contains the
offset of the corresponding main file record from the beginning of the main file.
The dBASE table contains feature attributes with one record per feature. The one-
to-one relationship between geometry and attributes is based on record number.
Attribute records in the dBASE file must be in the same order as records in the
main file. As an example, a shape file may be used to geographically reflect a cer-
tain country, wherein the shape of the country or state is reflected in the main file
and the index file, whereas additional information attributes about the country are
stored in one or more attributes in the dBASE table.
In order to make the information contained in a shape file accessible to a user or
further processing steps it must be converted into different data formats. Some
conversion tools are available to transform geographical data in XML formats like
GML which describes the geometries themselves and KML which describes how
to display them. However, conversion into a certain file format alone is not suffi-
cient to facilitate the use of shape files. An efficient retrieval of a certain shape
file among a plurality of other shape files is also needed.
The present invention is therefore in one aspect based on the technical problem to
facilitate the retrieval and management of geometric data, in particular shape files,
so that the geometric information stored in such a file is easily accessible to a user
or for further processing steps.
3. Summary of the invention

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In one aspect of the present invention, this problem is solved by an XML database
management system for providing geographic information according to claim 1.
In one embodiment, the XML database management system comprises a loader
capable to convert a geospatial data document, in particular a shape file, into an
XML document in accordance with a predefined XML schema, wherein the pre-
defined XML schema defines nontopological geometry and attributes to be stored
in a single XML node of the XML document, and an XQuery capability enabling
a user to retrieve the XML document based on one or more of its attributes.
The invention is based on the recognition that an XML database system can be
used to efficiently store and retrieve geographic information, if the XML docu-
ments, into which the geospatial data documents are converted, adhere to an XML
schema, which defines that the geospatial information and the related attributes
are stored together in a single node. As a result, an XQuery search can be per-
formed based on values of the attributes, wherein the search provides not only the
attribute but also the full geospatial document. Preferably, the XML database
management system further comprises an export capability for exporting the XML
documents in a scalable vector graphics (SVG) format and / or a KML format
and/or as a shape file, so that any retrieved geospatial document can immediately
be displayed or further processed.
In one embodiment, the XML schema for the loader is defined based on user in-
put. Accordingly, the user can define how the geospatial documents are trans-
formed into generic XML documents, which will in turn affect how the stored
documents can be searched with an XQuery.
According to a further aspect, the present invention relates to a method of provid-
ing geographic information comprising the steps of converting a geospatial data
document, in particular a shape file, into an XML document in accordance with a
predefined XML schema, wherein the predefined XML schema defines geospatial
data and attributes to be stored in a single XML node, and performing an XQuery

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based on one or more of the attributes to retrieve the XML document. The method
may further comprise the step of exporting the XML document in a scalable vec-
tor graphics (SVG) format and / or a KML format, and/or as a shape file.
Finally, the present invention relates to an XML database comprising any of the
above described XML database management systems and to a computer program
comprising instructions adapted to perform the above described method.
4. Short description of the drawings
In the following, embodiments of the present invention are further described with
reference to the following figures:
Fig. 1: A flow chart schematically illustrating an embodiment of a method ac-
cording to the invention;
Fig. 2: A schematic representation of an XML document with geographic infor-
mation and attribute information being stored in a single XML node; and
Fig. 3: An example of an XQuery for retrieving the XML document of Fig. 2
based on conditions imposed on the attribute.
5. Detailed description of preferred embodiments
In the following, exemplary embodiments of the method of the present invention
are described. It will be understood that the functionality described below can be
implemented in a number of alternative ways, for example in a management sys-
tem for a single XML database, in a distributed arrangement of a plurality of
XML databases, with an integral storage or an external storage, etc.. The database
management system could be tightly integrated with the database itself or be pro-

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vided separately. None of such implementation details is essential for the present
invention.
Fig. 1 presents a schematic flowchart describing exemplary steps of the process
for storing geospatial data in a XML database and for retrieving the stored data
using XQuery. As shown in step 1, the data may be provided as input in a variety
of file formats such as shape files having the extensions .shp, .shx and .dbf. Other
suitable file formats are also conceivable as input.
In step 2, the geographical data are converted by a mass loader (not shown) into
XML documents in accordance with a given XML schema. Depending on the
structure of a certain set of geospatial data, in particular the various attributes con-
tained in the .dbf-file of a shape file, an adapted XML schema may be used. Fur-
ther, the predefined XML schema will also influence, how a specific set geospa-
tial data can be later retrieved from the XML database.
After conversion, the resulting XML documents are stored in step 3 in an XML
database in a manner as any other XML document. The database available from
applicant under the name "Tamino" is one example of an XML database suitable
to perform step 3.
The predefined XML schema is in a presently preferred embodiment a Tamino-
specific XML schema. Thereby, it will inherit the following advantages of XML
schemas in Tamino:
Tamino defines document types ("doctypes") belonging to a given collec-
tion with their respective names and specifies whether they allow the storing
of XML or non-XML documents.

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While storing this document within Tamino, a schema ensures that every
instance stored in a doctype defined in that schema is valid with respect to
that schema.
Tamino associates e.g. indexing or collation options with elements and at-
tributes defined in the schema. These options are important for performance
and sorting issues.
Tamino associates mapping information with elements and attributes. This
feature allows to specify whether they are stored natively in Tamino or (via
X-Tension) in an external data store, e.g. Adabas or an SQL database. At
query time, these elements and attributes are retrieved from the external da-
tabase.
Tamino allows to specify trigger functions that are invoked when a docu-
ment is inserted into or deleted from the Tamino data store.
Fig. 2 presents a simplified example of an XML document containing geospatial
information, as provided by the conversion step 2 of Fig. 1. As can be seen, the
nontopological information 10 defining the shape of a polygon is stored in a sin-
gle node together with attribute information 20 on the geospatial object defined in
the XML document. In the example of Fig. 2, the node defines a state of India and
the attribute information indicates the number of population of the state. Whereas
the example of Fig. 2 presents only a single attribute 20, there could be many
more and also a hierarchy of tree-like structured attributes contained in a single
node.
An important advantage of the transformation into generic XML documents and
the subsequent storage in an XML database is the easy retrieval of the stored geo-
spatial data. As will be explained below with reference to the example of Fig. 3,

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the geospatial data can be easily retrieved by defining a query using XQuery on
the attributes.
In the XQuery example of Fig. 3, several conditions are defined on the node
, namely that it comprises an attribute "population" and that the value of
this attribute is within the indicated limits of 1000000 and 2000000. It is apparent
that this is only a simple example and that by far more complex queries on one or
more attributes of a node could be defined using XQuery in a manner, as it is
well-known to the person skilled in the art.
In step 4 of the flow chart of Fig. 1, the defined query is executed. As a result, the
XML database will provide one or more XML documents meeting the conditions
defined in the query. The results can either be simply output to a user, for example
by listing the names of the retrieved nodes. Alternatively or additionally, they
could be immediately further processed, for example by transforming the re-
trieved XML document into one or more specific output formats, which are suit-
able for further processing, such as rendering the geospatial object defined in the
XML document for subsequent display or printout.
One example of a format suitable for display is the KML format. KML is a file
format used to display geographic data in an earth browser, such as Google Earth,
Google Maps, and Google Maps for mobile. KML has a tag-based structure with
names and attributes used for specific display purposes. Thus, Google Earth and
Maps act as browsers for KML files. An output of the query results in the KLM
format allows for example to specify image overlays on a screen. Taking the ex-
emplary XQuery of Fig. 3, a possible response of the XML database would be to
present based on the geospatial information stored in the retrieved XML docu-
ment the shape of the Indian state of Gujarat on a screen or any other presentation
device.

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Another format suitable for export and further processing of the XQuery result is
the scalable vector graphics (SVG) format developed by Adobe. SVG enables
Web developers and designers to create dynamically generated, high-quality
graphics from real-time data with precise structural and visual control. The result-
ing SVG file could be used to display maps for countries or certain geographical
areas (e.g. oil-drilling claims) that are "related" to the content of the XQueries.
Finally, the XML database is preferably also capable to export the result of the
query as a shape file, i.e. in the same format, which was used for input of the geo-
spatial information in step 1 of the flowchart of Fig. 1.

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We Claims
1. An XML database management system for providing geographic informa-
tion comprising:
a. a loader capable to convert (1) a geospatial data document, in particular
a shape file, into an XML document in accordance with a predefined
XML schema, wherein the predefined XML schema defines geospatial
data (10) and attributes (20) to be stored in a single XML node of the
XML document; and
b. an XQuery capability enabling a user to retrieve (4) the XML document
based on one or more of its attributes.
2. The XML database management system according to claim 1 further com-
prising an export capability for exporting the XML document in a scalable
vector graphics (SVG) format and / or a KML format.
3. The XML database management system according to claim 1 or 2 further
comprising an export capability for exporting the XML document as a shape
file.
4. The XML database management system according to any of the preceding
claims, wherein the shape file comprises a .shp, .shx and .dbf file.
5. The XML database management system of any of the preceding claims,
wherein the XML schema for the loader is defined based on user input.
6. An XML database system comprising an XML database and a XML data-
base management system according to any of the claims 1-5.

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7. A method of providing geographic information comprising the steps of:
a. converting (1) a geospatial data document, in particular a shape file,
into an XML document in accordance with a predefined XML
schema, wherein the predefined XML schema defines geospatial data
(10) and attributes (20) to be stored in a single XML node of the XML
document; and
b. performing (4) an XQuery based on one or more of the attributes (20)
to retrieve the XML document.
8. The method of claim 7, further comprising the step of exporting the XML
document in a scalable vector graphics (SVG) format and / or a KML for-
mat, and / or as a shape file.
9. The method of claim 8, wherein the shape file comprises a .shp, .shx and
.dbf file.
10. A computer program comprising instructions adapted to perform a method
of any of the claims 7-9
Dated 23rd Day of October 2007

The present invention relates to an XML database management system for providing geographic information. In one embodiment, the XML database management system comprises a loader capable to convert (1) a geospatial data document, in
particular a shape file, into an XML document in accordance with a predefined XML schema, wherein the predefined XML schema defines geospatial data (10) and attributes (20) to be stored in a single XML node, and an XQuery capability
enabling a user to retrieve (4) the XML document based on one or more of its attributes (20).