CONSULTING ENGAGEMENT REPORT

GJXDM/IEEE 1512 Compatibility
Analysis Report

Final Report Submitted
March 28, 2007

Consulting Engagement Team Members
Jim Cabral
MTG Management Consultants, LLC

IJIS Institute Staff
Scott Parker
Project Manager

This project was supported by Grant No. 2003-LD-BX-0007 awarded by the Bureau of Justice Assistance. The Bureau of Justice Assistance is a component of the Office of Justice Programs, which also includes the Bureau of Justice Statistics, the National Institute of Justice, the Office of Juvenile Justice and Delinquency Prevention, and the Office for Victims of Crime. Points of view or opinions in this document are those of the author and do not represent the official position or policies of the United States Department of Justice.

1. Acknowledgements
2. Guiding Project
2.1. Consulting Team
2.2. Project Steering Committee
2.3. Project Advisors
3. Executive Summary
4. Background
5. Introduction and Approach
5.1. Model Information Exchanges
5.2. Develop Data Models
5.3. Map Data Models to XML
5.4. Develop Schemas
5.5. Develop Instances and XSL Stylesheets
5.6. Develop Transformations
6. Scope and Constraints
7. Findings
7.1. Intellectual Property Rights, or "Ownership"
7.2. Structure
7.2.1 Description of Analysis Methodology
7.2.2 Similarities
7.2.3 Differences
7.2.4 Summary
7.3. Elements
7.3.1 Description of Analysis Methodology
7.3.2 Similarities
7.3.3 Differences
7.3.4 Summary
8. Commentary
8.1. Lessons Learned in the Creation of GJXDM/IEEE 1512 Exchanges
8.2. Recommendations for Future Exchanges Between the GJXDM and IEEE 1512 Environments
Appendix A: List of Exchanges Modeled and Used in the Analysis
Appendix B: List of Exchanges Identified but Not Modeled in the Analysis
Appendix C: Chart of Properties and Elements
Appendix D: List of Exchanges Identified in the Justice Information Exchange Model
(JIEM) Appendix E: References/Bibliography
Appendix F: Glossary of Acronyms
Endnotes

1. Acknowledgements

The IJIS Institute acknowledges the work of MTG Management Consultants, LLC, and in particular, Jim Cabral in preparing this report.

This report, and the many ongoing activities of IJIS Institute's Intelligent Transportation Systems (ITS)/Public Safety (PS) Exchange Standards Project, would not exist without the full support of the ITS Joint Program Office, Federal Highway Administration (FHWA), Department of Transportation (DOT), and the Bureau of Justice Assistance (BJA) of the Office of Justice Programs (OJP) in the U.S. Department of Justice (DOJ). The continuing leadership and guidance of DOT and BJA are key elements to the success of this project, from which Traffic Management Centers and Public Safety Dispatch Centers across the United States will derive benefits.

The IJIS Institute is grateful for the support of the member companies and their professional representatives, as well as justice and transportation practitioners who devote time and share their invaluable expertise for projects such as these.

Scott Parker
Project Manager
IJIS Institute

2. Guiding Project

In 2005, the U.S. Department of Transportation, in partnership with the U.S. Department of Justice, Bureau of Justice Assistance, established the Intelligent Transportation Systems and Public Safety (ITS/PS) Information Exchange Project, managed by the IJIS Institute. The project's goal was to establish a standards-based approach to critical information exchange between transportation and public safety agencies, validated through laboratory and field testing. By facilitating faster and better communications and coordination, this project is enhancing daily operations and helping to ensure more immediate, safe, and effective response to routine incidents, natural disasters, terrorist acts, and other major incidents. Both public safety and transportation agencies will benefit from having more accurate and timely information to perform their role and the public will be better served.

To this point, each community has developed information exchange specifications unique to their own needs and systems. Transportation incident management utilizes standards developed in conjunction with the Institute of Electrical and Electronics Engineers (IEEE, 1512). In contrast, public safety relies on DOJ's Global Justice XML Data Model (GJXDM), supported by the Global Justice Information Sharing Initiative (Global Justiceⁱ), to define information exchange standards for the justice community.

Led by a steering committee comprised of both practitioner and industry representatives, and supported by technical working teams and subject-matter experts, the ITS/PS project is in the process of developing standard exchanges that incorporate both GJXDM and IEEE specifications. This work will allow transportation and public safety agencies to share information using the same standards, bridging the two communities in a real-time manner to improve communication and increase collaboration, while saving time and valuable resources. This project does not seek to supplant those existing intra-community standards, but instead focused on identifying the common information of interest to the two communities and focusing on the needs where those interests intersect. These GJXDM/IEEE exchanges provide a flexible methodology now and in the future for the transfer of this information, and will work in harmony with other information exchange initiatives such as the National Information Exchange Model (NIEM).

     2.1. Consulting Team

In order to further the efforts of the project and create this report, the IJIS Institute solicited the assistance and participation of senior and qualified consultants from its member firms. The following firms were selected by the IJIS Institute as the project consultants:

Jim Cabral IJIS Institute Consultant MTG Management Consultants, LLC www.mtgmc.com
Laci Porter IJIS Institute Consultant MTG Management Consultants, LLC www.mtgmc.com
Tomas Guerra IJIS Institute Consultant OZ Engineering www.ozengineering.com

     2.2. Project Steering Committee

In order to further the efforts of the project, the IJIS Institute solicited the assistance and participation of senior and qualified consultants from its member firms and practitioners from justice and transportation. The following individuals were selected as participants in the Project Steering Committee:

Eric Roecks (Chairman)
MTG Management Consultants, LLC
www.mtgmc.com

Ann Lorscheider
North Carolina Department of Transportation
www.ncdot.org

Bill Legg
Washington Department of Transportation
www.wsdot.wa.gov

Chandra Jonelagadda
Tetris Consulting
www.tetrisconsulting.com

Christopher Traver
Bureau of Justice Assistance, Department of Justice
www.ojp.usdoj.gov/BJA

Lieutenant Joe Balles
Madison, Wisconsin, Police Department
www.madisonpolice.com

Linda Dodge
ITS Joint Program Office, FHWA, DOT
www.its.dot.gov

Matthew Malec
City of Cleveland, Ohio
www.city.cleveland.oh.us

Lieutenant Melvina Apodaca
Los Angeles County, California, Sheriff's Department
www.lasd.org

Mike Sadler
Utah Department of Public Safety
www.publicsafety.utah.gov

Rob Spilker
Northrop Grumman Corporation
www.northropgrumman.com

Steve Barger
Intergraph Corporation
www.intergraph.com

Tom Dewey
Advanced Justice Systems

Tom Merkle
CapWIN
www.capwin.org

Wayne Gisler
Harris County, Texas, Public Infrastructure Department
www.co.harris.tx.us

     2.3. Project Advisors

The Project Steering Committee also had the assistance and participation of additional senior and qualified practitioners from justice and transportation. The following individuals were selected as the project advisors:

Ann Diephaus
Noblis
www.noblis.org

David Hellman
ITS Joint Program Office, FHWA, DOT
www.its.dot.gov

David Kelley
Sub-Carrier Systems

Lee Simmons
ITS Joint Program Office, FHWA, DOT
www.its.dot.gov

Patricia Gerdon
IEEE Standards Association
www.standards.ieee.org

Richard Glassco
Noblis
www.noblis.org

Robert (Bob) Greeves
Bureau of Justice Assistance, Department of Justice
www.ojp.usdoj.gov/BJA

Ron Ice
R.C. Ice and Associates

Ted Smith
Noblis
www.noblis.org

3. Executive Summary

One objective of the IJIS Institute's Intelligent Transportation System (ITS)/Public Safety (PS) Exchange Standards Project (ITS/PS Project) was to understand the issues and complexities in defining eXtensible Markup Language (XML) information exchanges using two sets of standards - the Global Justice XML Data Model (GJXDM) used by public safety and the IEEE 1512 specification used by transportation. Another objective was to create several standardized high-value exchanges associated with traffic-related incident management - 12 information exchanges resulted. During the course of the project, the project team arrived at the following findings:

• While both standards define data structures and elements using XML schema, the IEEE 1512 provides a more complete set of messages for traffic-related incident management exchanges, while the GJXDM provides a more flexible set of content, leaving it up to the implementer to define the messages appropriate for each exchange.
• There is significant overlap in the content of the two standards due to the reuse of several large GJXDM data structures in the IEEE 1512 specification.
• Due to the focus of the specification on traffic-related incident management, the IEEE 1512 specification mapped to a much higher percentage of propertiesⁱⁱ in the data model for the 12 information exchanges than the GJXDM.
• The eXtensible Stylesheet Language Transformation (XSLT)ⁱⁱⁱ language is a feasible option for implementing transformations to convert between GJXDM and IEEE 1512 representations of the same exchange.

4. Background

The Global Justice XML Data Model (GJXDM) defines XML elements and data structures for describing information commonly exchanged between public safety systems. Similarly, the DRAFT P1512 specification IEEE Standard for Common Incident Management Message Sets for Use by Emergency Management Centers (IEEE 1512) defines XML elements and data structures for describing information commonly exchanged between Traffic Management Center (TMC) systems. The ITS/PS Project included the modeling of 12 of the most useful public safety/transportation information exchanges for traffic-related incident management using both the GJXDM and IEEE 1512 specifications and the development of XSLT stylesheets between the two data models. This report is a summary of the lessons learned in that project, including:

• A comparative analysis of the relative strengths and weaknesses of the GJXDM Version 3.0.3 and the Draft P1512 specification IEEE Standard for Common Incident Management Message Sets for Use by Emergency Management Centers, Rev35 specification for describing traffic-related incident management information exchanges between public safety computer-aided dispatch (CAD) systems and TMC systems.
• A compatibility analysis between the GJXDM and IEEE 1512 specifications within the context of the defined traffic-related incident management information exchanges.

5. Introduction and Approach

Global Justice publishes guidelines for the development of Information Exchange Package Documentations (IEPDs)^iv using GJXDM content. An IEPD defines messages used in the implementation of one or more exchanges. In order to support both the GJXDM and the IEEE 1512 specifications, the ITS/PS Project adapted the standard IEPD development process as follows:

     5.1. Model Information Exchanges

In the initial step, a Justice Information Exchange Model (JIEM) was developed that identified and described the most common exchanges between public safety CAD systems and TMC systems based on the experience of participating subject matter experts from the public safety and transportation industries. Each exchange included the sending and receiving agencies and the processes, events, and conditions related to the exchange, as well as the name of the documents or messages that were transferred. The project committee identified 22 potential incident management information exchanges and selected 12, deemed as the most important, for XML modeling in the ITS/PS Project. (These exchanges are listed in Appendices A and B.)

The project committee was comprised of five representatives of transportation (including local, state, and federal), five representatives of public safety (including local, state, and federal), five technology industry representatives, and ten advisors (a mix of practitioners and industry). These members represented a mix of subject matter experts and technologists.

     5.2. Develop Data Models

Next, the subject matter experts collaboratively developed Unified Modeling Language (UML) models for each of the 12 exchanges selected for XML modeling. These models defined the business objects (i.e., vehicles, places, and things) in the exchange, the properties for each object (e.g., make, model, license number), and the relationships between objects. These data models provide the data requirements for each exchange independent of any particular technology. Three hundred and thirteen (313) properties were identified in this process.

     5.3. Map Data Models to XML

In the third step, the consulting team-familiar with the GJXDM and IEEE 1512 specifications-identified XML structures and elements from each standard that corresponded to the objects and properties in each of the 12 data models. When the GJXDM and IEEE 1512 specifications did not include an appropriate XML structure and element for an object or property, the analysts defined local extensions^v appropriate to that standard. The lessons learned from mapping the data models to the GJXDM and IEEE 1512 specifications are the focus of this report, and the process of mapping the structures and elements is detailed in Section 6.

     5.4. Develop Schemas

Based on the XML mappings, the consulting team generated both GJXDM and IEEE 1512 XML Schema Definition (XSD) files that covered the scope of exchanges. The GJXDM files included a set of GJXDM subset schemas, a local extension schema, and a document schema for each exchange. The IEEE 1512 files included schemas defined within the specification, as well as a set of local extensions.

     5.5. Develop Instances and XSL Stylesheets

Based on the schemas, the consulting team generated example GJXDM and IEEE 1512 instances and eXtensible Stylesheet Language (XSL) stylesheets for each exchange. The instances included example data and simulated actual messages. The stylesheets provided a mechanism to view an XML instance as an HTML Web page.

     5.6. Develop Transformations

Finally, in the case of one exchange (the Incident Notification exchange), the consulting team developed XSLT stylesheets for converting a GJXDM instance to an IEEE 1512 instance and vice versa.

6. Scope and Constraints

The scope of the ITS/PS Project was limited to the following exchanges:

• Exchanges between traffic management center (TMC) systems and public safety CAD systems. These exchanges include initial request and alerts, as well as subsequent exchanges for updated status and clearance sharing.
• Exchanges of information between TMC systems and public safety CAD systems to assist in understanding the location and availability of critical resources (e.g., dynamic text signage, cameras) and the existence of planned or current events or activities.

Early in the project, a Justice Information Exchange Model (JIEM) was developed that identified and described the most common exchanges within this scope. From the JIEM exchanges, 12 representative exchanges were selected based on anticipated benefit for data modeling and mapping to the GJXDM and IEEE 1512 specifications. The complete list of information exchanges analyzed in this project is provided in Appendix A.

To date, XSLT stylesheets have been developed between the GJXDM and IEEE 1512 for the Incident Notification exchange.

7. Findings

This section is a comparative analysis of the issues of mapping the data models in the 12 traffic-related incident management information exchanges to the structures and elements in the GJXDM and the IEEE 1512 specifications.

     7.1. Intellectual Property Rights, or "Ownership"

Although not a technical finding, it is important to make a note of the difference between the two standards regarding intellectual property rights, or "ownership".

GJXDM is a non-proprietary standard provided by the Global Justice Information Sharing Initiative (Global Justice) operating under the auspices of the Office of Justice Programs (OJP), U.S. Department of Justice.

The IEEE 1512 family of standards is provided by the Institute of Electrical and Electronics Engineers (IEEE), working in cooperation with the United States Department of Transportation (USDOT). IEEE retains intellectual property rights for the IEEE 1512 family of standards.

     7.2. Structure

          7.2.1 Description of Analysis Methodology

Objects in the data model were mapped to GJXDM types and IEEE 1512 message sets and data frames. When mapping objects in the data models to these structures in each standard, the consulting team used the following process to determine the best possible mappings:

• Selected a structure with the same definition as the data model object.
• If no structures matched, selected a structure and elements with similar definitions to the properties contained in the data model object.
• When choosing between multiple structures, selected the structure that matches the highest number of properties in the data model object.
• When no structures matched the data model object, identified the object as mapping to a local extension in that standard.
• When an object mapped to a structure in one standard (e.g., GJXDM) and a local extension in the other standard (e.g., IEEE 1512), defined the local extension based on the structure in the other standard.
• When an object did not map to a structure in either standard, defined a local extension structure that was compatible with both standards.

          7.2.2 Similarities

The structures in the GJXDM and IEEE 1512 specifications share the following similarities:

• Both standards use XML schemas to define data structures and elements.
• Both standards use a limited set of XML schema options. In other words, not all XML schemas are acceptable GJXDM or IEEE 1512 schemas.
• Both standards use compatible schemas for a number of complex structures, including those for person, property, and vehicle.

          7.2.3 Differences

The structures in the GJXDM and IEEE 1512 specifications have the following differences:

• The GJXDM makes great use of object inheritance, the definition of a specific type (e.g., j:Event/ActivityID) based on a more abstract type (j:IDType). GJXDM structures generally inherit elements from a multilevel hierarchy of complex objects. The IEEE 1512 specification makes very limited use of object inheritance. Most IEEE 1512 elements (e.g. ReferenceID) are based on the simple types defined by the XML specification (xs:string).
• Due to the size and complexity of the GJXDM, implementation of GJXDM exchanges generally requires the definition of a subset of the complete GJXDM schemas appropriate to the specific exchanges. The IEEE 1512 does not support the creation of subset schemas.
• As a general data model, messages that include GJXDM content are defined in Information Exchange Package Documentations (IEPDs) that are defined outside the GJXDM according to a set of standard guidelines. Since the IEEE 1512 specification is specific to traffic-related incident management, the standard defines the messages that must be supported in order to be compliant with the specification.
• In addition to messages, the IEEE 1512 specification also defines certain structures known as "data frames," which are logical groupings of data elements that describe parts of messages. The GJXDM does not distinguish between different types of data structures.
• Extensions to the GJXDM may be inserted at any point in the data model as long as the extensions conform to the GJXDM IEPD Guidelines. The IEEE 1512 specification provides defined extension points and extensions at other points in the data model are not allowed.

          7.2.4 Summary

While both standards define data structures using XML schema, the GJXDM and IEEE 1512 specifications differ in their requirements for compliance with the standard. While the IEEE 1512 specification defines the complete set of messages required for an implementation, the GJXDM defines the content and allows implementers to define the messages themselves.

7.3. Elements

          7.3.1 Description of Analysis Methodology

Once the objects in the data models were mapped to GJXDM and IEEE 1512 structures, the 313 properties in the data models were mapped to GJXDM and IEEE 1512 elements, message sets, and data frames. When mapping properties in the data models to these elements in each standard, the consulting team used the following process to determine the best possible mappings:

• Selected the element in the structure with the same definition as the data model property.
• For data model properties that matched coded elements in both standards, selected either the GJXDM or the IEEE 1512 code list that best matched the definition of the property. If neces-sary, defined a local extension in one standard based on the code list in the other standard.
• If no elements in the structure matched, selected an element from the complete GJXDM or IEEE 1512 standard with a similar definition of the property in the data model.
• When choosing between multiple elements, selected the element that best matched the definition of the property in the data model.
• When no elements matched the data model property, identified the property as mapping to a local extension in that standard.
• When a property mapped to an element in one standard (e.g., GJXDM) and a local extension in the other standard (e.g., IEEE 1512), defined the local extension based on the element in the other standard.
• When a property did not map to an element in either standard, defined a common local extension element that is compatible with either standard.

          7.3.2 Similarities

Mapping the data models to GJXDM and IEEE 1512 elements illustrated the following similarities between the two standards:

• 121 of the 313 properties (or, 39%) in the data model mapped to elements in both standards (Reference Code "A" in Appendix C table). This suggests that there is a significant overlap between the two standards related to modeling traffic-related incident management informa-tion exchanges. Many of these similarities are due to the fact that both standards use com-patible schemas for a number of complex structures, including those for person, property, and vehicle. However, some elements that were mapped to both standards are defined in slightly or significantly different structures (e.g. time ranges such as EventInformation/StartTime and EventInformation/StopTime). Examples of groups of elements in com-mon between the two standards include:
  • Address.
  • Person contact information.
  • Dispatcher information.
• 51 of the 313 properties (or, 16%) in the data model did not map to elements in either standard (Reference Code "B" in Appendix C table). This indicates that, even used in combination, there are still gaps in the scope of these standards related to traffic-related incident management. Examples of groups of properties missing in both standards include:
  • Requests for services.
  • Service decisions.

          7.3.3 Differences

Mapping the data models to GJXDM and IEEE 1512 elements illustrated the following differences between the two standards:

• 136 of the 313 properties (or, 43%) in the data model mapped to elements in the IEEE 1512 specification but not to the GJXDM (Reference Code "C" in Appendix C table). This indi-cates that the IEEE 1512 specification is more complete with regard to traffic-related incident management than the GJXDM. Examples of groups of elements in the IEEE 1512 specifica-tion that did not map to the GJXDM specification include:
  • Assets (resources).
  • Deployments and planned deployments (resource assignments).
  • Incident command structures.
  • Lanes and links designations.
  • Lane/road closures, detours, and restrictions.
  • Staging areas.
• Five of the 313 properties (or, 2%) in the data model mapped to elements in the GJXDM but not to the IEEE 1512 specification (Reference Code "D" in Appendix C table). This suggests that the GJXDM defines few traffic-related incident management elements that cannot be mapped to the IEEE 1512 specification. This is logical since the IEEE 1512 specification imports a number of complex structures from the GJXDM, including those for Person, Property, and Vehicle. Example elements in the GJXDM that did not map to the IEEE 1512 specification include:
  • Property involved in an incident.
  • Vehicle identifiers (e.g., car #1, car #2).

          7.3.4 Summary

A significant majority (82%) of the properties in the data model mapped to elements in the IEEE 1512 specification. By comparison, only 40% of the properties in the data model mapped to elements in the GJXDM. This difference can be attributed to the following facts:

• The IEEE 1512 specification is focused on the requirements for management of transporta-tion-related incidents. The GJXDM models for incident management are designed for all incidents and are therefore more generalized.
• The IEEE 1512 specification defines specific messages for most of the information exchanges modeled in this project. The GJXDM is more flexible and does not define messages in the standard itself.

8. Commentary

This section describes some of the lessons learned in this project and recommendations for mapping information exchanges to the GJXDM and the IEEE 1512 specifications.

     8.1. Lessons Learned in the Creation of GJXDM/IEEE 1512 Exchanges

To our knowledge, this project was the first attempt to map information exchanges between two data models with the complexity of the GJXDM and the IEEE 1512 specifications. As expected, the project produced a number of lessons learned regarding what works and what does not work related to using these data models. These lessons include the following:

• Although the GJXDM and the IEEE 1512 specifications share some elements, including the GJXDM Person, Property, and Vehicle structures, there are significant differences in the focus, content, and structure of each data model. The similarities and differences between the two models are described in detail in the previous section.
• There was a tendency by some subject matter experts to want to reuse the structures in one standard or the other in the generation of the data models. The decision was made to avoid that approach. While that approach would have made it much simpler to map the data model to one standard, it would not simplify mapping to the other standard and, most importantly, it would not necessarily describe the real-world business requirements.
• When properties mapped to only one or to neither standard, it was useful to map these properties to common structures and elements that could be used with both standards to simplify the transformations between the standards.
• The development of XSLT stylesheets to transform between the GJXDM and the IEEE 1512 versions of the Incident Notification exchange was complicated by the large number of mappings in this complex exchange, as well as the need to convert date and time formats between the two standards. The development of the stylesheets was simplified through the use of Altova Mapforce, a software tool for generating XSLT stylesheets. The date and time conversion issues were overcome through the use of XSLT stylesheets provided by a member of the project team.

     8.2. Recommendations for Future Exchanges Between the GJXDM and IEEE 1512 Environments

In addition to the lessons learned in this project, the following considerations are recommended for those defining future exchanges between the GJXDM and IEEE 1512 environments:

• The JIEM model developed in this project includes 64 priority information exchanges between public safety and transportation systems associated with traffic-related incident management, and only a subset of those were modeled in this project (see Appendix D for a list of the JIEM exchanges).^vi The exchanges not included in the ITS/PS Project should be considered high priority in any future effort to model traffic-related incident management exchanges using the GJXDM and IEEE 1512 specifications.
• The data models developed in this project were intended to be reusable in future projects. For instance, with the co-release of the GJXDM 4.0 and the National Information Exchange Model (NIEM) 2.0, the current data models could be mapped to the new standard with some changes to the existing GJXDM mappings but no changes to the underlying data model. In addition, the data models for any additional traffic-related incident management information exchanges should be able to leverage the existing data models, particularly the Incident Notification data model.

Endnotes

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