extensible language for data description in diagnostic of traffic

extensible language for data description in diagnostic of traffic

PRACE NAUKOWE POLITECHNIKI WARSZAWSKIEJ
z. 113
Transport
2016
6/
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1
Uniwersytet Technologiczno-:]! w Radomiu,
(,?
EXTENSIBLE LANGUAGE FOR DATA
DESCRIPTION IN DIAGNOSTIC OF TRAFFIC
CONTROL SYSTEMS
The manuscript delivered: March 2016
Abstract: Modern railway traffic control systems commonly use Information Technology (IT) in
order to perform processing and logging diagnostics data in diagnostic centres. The lack of standards
for diagnostic data structures and the lack of common mechanisms of acquiring data causes, that the
producers of systems use their own solutions in this domain. Thus, in spite of using modern
technologies, there is a great difficulty in obtaining consistent diagnostic data and makes its further
analysis difficult. In the article the using of the specialised XML-based markup language was
proposed. This language can be used to unify structures of diagnostic data obtained from the different
railway traffic control systems. The unification of diagnostic data structures would allow not only for
building interfaces between railway traffic control systems and diagnostic centres, but also for
developing the unified diagnostic system.
Keywords: railway traffic control systems, diagnostics, XML
1. INTRODUCTION
The railway traffic control systems are responsible for the safety and efficiency of trains
movement on the rail network. Therefore, it is essential to ensure high reliability of these
systems [7, 8]. Extremely helpful in achieving this objective may be centralized diagnostic
systems, which, through acquisition of diagnostic data and usage of inference methods can
help detect failures and minimize service and maintenance costs. Modern railway traffic
control systems commonly use Information Technology (IT) in order to perform
processing and logging diagnostics data in diagnostic centres [5, 6]. However, there is
a lack of acquiring and structuring data standards what causes that the producers of the
railway traffic control systems use their own solutions in this domain [9]. Therefore,
despite the lack of technological barriers, there is a great difficulty in obtaining consistent
diagnostic data and analysing them. The issue of unifying form of railway traffic control
system diagnostic data and its structures is very important. Unified data structure, which is
application-independent and vendor-independent, should simplify data exchange between
railway systems and should allow to use various railway IT applications for data
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acquisition, processing, visualisation and archiving. In this paper XML-based, specialized
for railway traffic control system diagnostic data markup language was proposed.
2. XML
XML, or extensible markup language was originally used to store and exchange data
between heterogeneous systems. Currently, as a set of simple rules, XML is often used to
design other custom markup languages. Based on the XML specification many new
markup languages were developed and acknowledged as standards, for example xHTML,
RSS, MathML, CML, FpML, ebXML, GML, SVG, MusicML, SMIL, RDF, OWL [12].
XML was also used to develop standards for use in road transport - TransXML and rail
transport – RailML [13, 14]. XML application comprehensiveness it is a result of its
numerous advantages:
openness – XML is open W3C standard supported by software industry market
leaders, and based on international standards,
strict syntax and parsing requirements – make the necessary parsing algorithms
extremely simple, efficient, and consistent, allows validation using schema languages
such as XSD,
comprehensiveness – the hierarchical structure is suitable for most types of data,
even in the case of the complex data structure; XML is commonly used as
a format for online and offline document storage and processing,
flexibility and extensibility – data structure is easy to extend and modify,
separates content from presentation – the look and feel of an XML document can be
controlled by stylesheets, allowing change the look of a document without editing its
content,
simplicity – simple and regular syntax that makes information coded in XML easy
to read and understand,
readability – it is a simultaneously human- and machine-readable format,
internationalization – XML support multilingual documents and Unicode standard,
wide availability of tools – XML is supported by many software vendors, so there are
numerous and readily available parsers and editing tools,
usability across the Internet.
Each custom markup language created using XML specification should satisfy a list of
syntax rules provided in the specification. Well-formed document conforms to the rules:
XML documents should begin with an XML declaration (XML prolog) which
specifies the version of XML being used,
a single "root" element contains all the other elements (tags),
content must be properly nested (parents within roots, children within parents),
elements can contain attributes, attribute values must always be quoted; either single
or double quotes can be used,
all XML elements must have a closing tag,
Extensible language for data description in diagnostic of traffic control systems
313
element names must start with a letter or underscore; can contain letters, digits,
hyphens, underscores, and periods; cannot contain spaces,
the element tags are case-sensitive.
A "well formed" XML document is not the same as a "valid" XML document. A "valid"
XML document must be well-formed, but in addition, it must comply with the restraints
stated in document type definitions. This requirement only makes sense for the documents
with defined schema. W3C XML Schema is currently the most popular standard to formal
describing constraints on the structure of an XML document [10]. The purpose of an XML
Schema is to define the elements and attributes that can appear in a document, the number
of child element and data types and default values for elements and attributes. XML
Schema standard allow to define new markup languages. Therefore, the authors used it for
this purpose. In the following sections of the article the new defined markup language
intended to describe data acquired from railway traffic control system was presented.
3. DESCRIPTION OF DIAGNOSTIC DATA FOR THE
RAILWAY TRAFFIC CONTROL SYSTEMS
Based on XML syntax an exemplary specification of document structure in the form of
XML Schema file was developed. This specification can be a simple version of the markup
language specialized for acquisition diagnostic data which are gathered from railway
traffic control systems. In the specification the "faults" type was defined, which is
a complex type and contains the declaration of the element "fault".
<xs:element name="faults">
<xs:complexType>
<xs:sequence>
<xs:element ref="fault"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:simpleType name="ID">
<xs:restriction base="xs:integer">
<xs:minInclusive value="1"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="fault">
<xs:complexType>
<xs:sequence>
<xs:element ref="location"/>
<xs:element ref="system"/>
<xs:element ref="faultType"/>
<xs:element ref="startTime"/>
<xs:element ref="endTime"/>
</xs:sequence>
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<xs:attribute name="id" use="required" type="ID"/>
</xs:complexType>
</xs:element>
This element is composed of sub-elements:
"location" with details about the railway object, in which the railway traffic control
system was located,
"system" with details about the railway traffic control system,
"faultType" with details about the failure
"startTime" and "endTime" with time stamps of the appearance of the failure.
Attribute of the element "fault" is the "ID" number which is defined on the basis of
a simple integer. The element "location" is a complex type having sub-elements:
"stationName", "lineNumber" and "position" which are also simple types, respectively:
string, integer, integer and sub-element "geoCoord", which indicates the geographic
location of the railway traffic control system.
<xs:element name="location">
<xs:complexType>
<xs:sequence>
<xs:element ref="stationName"/>
<xs:element ref="lineNumber"/>
<xs:element ref="position"/>
<xs:element ref="geoCoord"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="stationName" type="xs:string"/>
<xs:element name="lineNumber" type="xs:integer"/>
<xs:element name="position" type="xs:integer"/>
<xs:element name="geoCoord" type="posGPS"/>
In order to specify the latitude/longitude the element "geoCoord" type "posGPS" was
defined. This element includes two sub-elements "latGPS" and "lonGPS" respectively
"latitudeType" and "longitudeType".
<xs:simpleType name="latitudeType">
<xs:restriction base="xs:decimal">
<xs:minInclusive value="-90.0"/>
<xs:maxInclusive value="90.0"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="longitudeType">
<xs:restriction base="xs:decimal">
<xs:minInclusive value="-180.0"/>
<xs:maxExclusive value="180.0"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="posGPS">
<xs:sequence>
Extensible language for data description in diagnostic of traffic control systems
315
<xs:element ref="latGPS"/>
<xs:element ref="lonGPS"/>
</xs:sequence>
</xs:complexType>
<xs:element name="latGPS" type="latitudeType"/>
<xs:element name="lonGPS" type="longitudeType"/>
Next element, which is the "system" has a string type attribute. The elements
"startTime" and "endTime" are declared as dateTime. "FaultType" (complex type) with the
attribute “alarmType” (string) and sub-elements: "code", "confirmState", "description" is
the last element. The "Code" element is the simple type hexBinary. The "confirmState" is
the type of confirmation defined on the basis of string, while "description" is a simply
string.
<xs:element name="system">
<xs:complexType>
<xs:attribute name="type" use="required" type="xs:string"/>
</xs:complexType>
</xs:element>
<xs:simpleType name="alarmType">
<xs:restriction base="xs:string">
<xs:enumeration value="errorMessage"/>
<xs:enumeration value="diagnosticMessage"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="confirmation">
<xs:restriction base="xs:string">
<xs:enumeration value="true"/>
<xs:enumeration value="false"/>
</xs:restriction>
</xs:simpleType>
<xs:element name="faultType">
<xs:complexType>
<xs:sequence>
<xs:element ref="code"/>
<xs:element ref="confirmState"/>
<xs:element ref="description"/>
</xs:sequence>
<xs:attribute name="type" use="required" type="alarmType"/>
</xs:complexType>
</xs:element>
<xs:element name="code" type="xs:hexBinary"/>
<xs:element name="confirmState" type="confirmation"/>
<xs:element name="description" type="xs:string"/>
<xs:element name="startTime" type="xs:dateTime"/>
<xs:element name="endTime" type="xs:dateTime"/>
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When an abstract structure design documents (XML Schema) the graphic notation is
often used [15]. The article visualise the created schema (Fig. 1).
Fig. 1. Visualization of the scheme in the XSD Diagram
Validation of the sample XML document containing information about a single failure
was performed with the use of the XML parser. For this purpose previously defined XML
Schema was used.
<?xml version="1.0" encoding="UTF-8"?>
<faults xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="diagsrk.xsd">
<fault id="1">
<location>
<stationName>Radom</stationName>
<lineNumber>8</lineNumber>
<position>103</position>
<geoCoord>
<latGPS>51.391773</latGPS>
<lonGPS>21.156334</lonGPS>
Extensible language for data description in diagnostic of traffic control systems
317
</geoCoord>
</location>
<system type="LO_Frausher"></system>
<faultType type="diagnosticMessage">
<code>05</code>
<confirmState>false</confirmState>
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</faultType>
<startTime>2016-01-22T09:30:47</startTime>
<endTime>2016-01-22T09:40:21</endTime>
</fault>
</faults>
4. CONCLUSIONS
XML language is constantly evolving and finding new applications. In accordance with
XML specification the new standards are formed, while the others are still being developed
and expanded. The authors of the article inspired with this technology suggested using of
XML in the diagnostics of the railway traffic control systems. Nowadays each of the
producers offer their own solutions, which are not coherent both in scope of acquired
diagnostic data as well as the method of its representation. Developing the common
standard based on XML would allow to standardise the diagnostic data structures gathered
from the railway traffic control systems. Such an approach would ensure not only to design
interfaces between railway traffic controls systems and diagnostic centres, but also allow to
develop a unified diagnostic system [1, 2, 7]. It would be undoubtedly very helpful in
building centralized diagnostic systems [3, 4]. As a result, this may lead to minimizing the
costs of maintenance and servicing of the railway traffic control systems.
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'!uczowe: systemy sterowania ruchem kolejowym, diagnostyka, XML
ACKNOWLEDGEMENT
The paper was carried out as a part of the research project of the National Centre for
Research and Development NCBiR NR PBS3/A6/29/2015, titled „The system for
maintenance data acquisition and analysis of reliability and safety of traffic control
systems".