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					Bentley ArcGIS Connector
      ®      ®             ™




                           ®
Introduction

       ESRI, as a GIS software products company, and Bentley Systems, Incorporated,
       as a developer of solutions for architecture/engineering/construction (AEC)
       professionals, both provide graphically oriented applications premised on a
       spatial context.

       These applications are often used in organizations served by both Bentley
       and ESRI. Such organizations include municipalities, transportation agencies,
       national government agencies, utilities, and others.

       While Bentley and ESRI applications create and maintain data in a common
       coordinate space, they are designed for unique purposes and therefore used
       by individuals with distinct organizational functions.

       ESRI users typically perform planning and analysis functions. Bentley users
       design, engineer, build, and operate roadways, buildings, plants, communication
       networks, and other large constructed assets.

       The planning professional requires a broad view of spatial information and the
       ability to work with large areas. Engineers create and work from sets of detailed
       drawings and models, with spatial information, and require a rich set of 2D and
       3D geometry-based engineering and design tools.

       The needs of the planner are best met by a continuous database: the geodata-
       base. The engineer’s requirements continue to be best met by a model and
       drawing paradigm.

       Yet, despite distinct roles, planners and engineers depend upon each other to
       conduct their work. Planners need accurate information on as-built conditions,
       and engineers and architects need the context of plans to create their designs.
       Operational staff need access to all of this information. The work is not static but
       synergistic, dynamically integrated, and recursive.

       Despite the practical need to share information, it is very difficult to share
       digital content between planners and AEC professionals. Very little true
       functional integration exists between AEC and GIS solutions.




       Bentley ArcGIS Connector                                                          1
Together, Bentley and ESRI provide true interoperability solutions for
both clients and servers. For a broad view of the entire initiative, read
the Bentley-ESRI AEC/GIS Interoperability White Paper available at:
http://www.bentley.com/aecgis.

This white paper focuses specifically on server-to-server interoperability
between the ESRI ArcGIS continuous database server (ArcSDE® Geodatabase)
and the Bentley AEC content management server (Bentley® ProjectWise®).




Bentley ArcGIS Connector                                                     2
Server-to-Server Interoperability

       Interoperability is most beneficial when it is implemented to support real-world
       workflows. Workflows must be flexible and must consider the dynamic interaction
       between groups and among individuals.

       Such interoperability between the ESRI ArcGIS environment and Bentley’s
       managed environment (based on ProjectWise) is enabled through a Bentley
       product called the Bentley ArcGIS Connector.




       This connector enables MicroStation® users that manage AEC content within a
       managed environment to implement any number of workflows that require the
       exchange of information with the ESRI geodatabase. To better appreciate the role
       of the connector in real production environments, three typical workflows are
       detailed in this paper: “extract from the geodatabase”; “capture and post to the
       geodatabase”; and “extract, design, post.”

       Extract from the Geodatabase
       Engineering projects often require the use of landbases or existing network infor-
       mation as context when creating or editing AEC content. When the geodatabase
       is implemented as the continuous representation of the landbase and/or network,
       users need to extract the relevant information from the geodatabase into managed
       MicroStation design files (DGNs).

       To accomplish this extraction, the Bentley AEC content management platform
       (ProjectWise) provides a simple but powerful wizard for specifying what
       information to extract and how.

       Bentley ArcGIS Connector                                                        3
Definition of the Target Geodatabase Content
Once the geodatabase is selected and the connection is established, the user can
select the desired feature datasets and classes for extraction from a specific version.
The connector recognizes the following feature classes with their attributes:

• Point features with a simple point or multipoints
• Line features, which can be made of multiple paths of lines, circular arcs,
  elliptical arcs, and Bezier curves
• Polygon features of one or many rings
• Annotation features, which could be simple or feature-linked

To complement feature classes, annotation relationship classes can also be
extracted. Part of the richness of the geodatabase is its ability to model and
maintain the relations between features or between features and tables. These
relations are also extracted for future use when browsing or editing features.

In the first release, the ArcGIS Connector will support what most organizations
typically require, particularly those that primarily maintain shapefiles and cover-
ages in the geodatabase. Future support is also planned for geometric networks,
raster, dimension classes, and TIN datasets.

The Area(s) of Interest
While the geodatabase is mostly used to store a continuous representation of the
earth, engineering projects are often limited to a much smaller area or bound to
a cartographical grid system made of tiles.

For this reason, users may
opt for an area covering
the feature class(es) extent.
Alternatively, the user may
specify a polygonal area
or multiple tiles of a grid
system, as shown in the
image below.

The spatial reference sys-
tem of the geodatabase
content is also recognized,
and can be reprojected to
the coordinate system
enforced in the engineering project.




Bentley ArcGIS Connector                                                             4
Managed Self-contained Design Files
Before the extraction can take place, one must decide how the features will
be organized and symbolized in the DGN file, since the geodatabase does not
store symbology metadata (except for annotation features). While there will be
reasonable defaults proposed, one might prefer to control the rules that dictate
how a specific feature must be presented, such as symbology (color, line type,
line width, etc.), level, and so forth. In version 8.5 of MicroStation GeoGraphics®,
these rules are expressed in the XFM Schema (XFM stands for XML Feature
Modeling). Provisions are made so that the user can define the XFM Schema
once and reuse it for multiple different extractions.

The generated DGNs are considered self-contained; all the feature class content
(geometry and attributes) is stored within the DGN elements as XML without
requiring database links back to the geodatabase. This architecture will facilitate
disconnected use, since all the information is available offline. This approach
also permits the association of a version to a DGN so that the project leader can
track the exact content and relate it to a specific milestone of an AEC project.

Keeping geometry and attributes together will also leverage many MicroStation
functions like Undo/Redo, Design History, and Digital Rights. The following
image of MicroStation GeoGraphics shows extracted layers and a tool for
browsing the attributes of multiple features within a self-contained DGN file.

                                                     The DGN files are managed
                                                     in the sense that numerous
                                                     metadata (selection of
                                                     geodatabase content, area
                                                     of interest, translation rules
                                                     to DGN elements, last
                                                     extraction date, and so on)
                                                     are kept along with the
                                                     DGN document in the AEC
                                                     content management server.
                                                     This capability permits
                                                     engineers to easily
                                                      determine such questions as:

• What is the landbase intersecting my current project?
• Can I see the electrical network before and after a construction project?
• When was this landbase extracted from the geodatabase? Is it up to date?




Bentley ArcGIS Connector                                                           5
Capture and Post to the Geodatabase
Since MicroStation and MicroStation GeoGraphics are tremendously productive
tools for capturing mapping and network data, another frequent workflow
involves posting such data to the geodatabase.

A MicroStation GeoGraphics v8.5 administrator will define an XFM Schema that
describes which feature and attributes can be created, the rules for placing them,
the dialogs for entering and validating attribute values, the rules for presenting
them with proper symbology, and so forth. An easy-to-use administrator utility
supports the creation of a new schema, or schemas may be imported from another
source such as the geodatabase or a MicroStation GeoGraphics project.

Once the XFM Schema is
created, a MicroStation
GeoGraphics session can
create new features using
the provided tools. As an
example, the following
drawing illustrates that
only valid cable types
can be selected from a
domain list.

Once the DGN file is
checked into the AEC
content management
platform, it can be posted
into the geodatabase
through the connector.

When posting to a geodatabase, a new version is created in the geodatabase
that receives the new feature instances. At this precise moment, the new features
are part of the geodatabase and are fully viewable or editable with ArcMap Editor.
However, it will often be part of the workflow to commit these new features
 into a target version (often the default version) for use in production. Again, to
support a particular workflow that is enforced in an organization, several options
are offered:

• The planner might prefer to control the reconciliation of the new version
  with a target version using ArcMap® Editor tools. This alternative will often be
  selected if custom applications are used for updating other tables or systems.



Bentley ArcGIS Connector                                                         6
• Alternatively, the Bentley ArcGIS Connector can be instructed to attempt the
  commit operation to a target version. If no conflicts are detected, then the
  operation is successful and is registered in the Audit Trail within ProjectWise.
  However, if conflicts are detected, the operation is aborted, registered in
  the Audit Trail, and a notification is sent to the administrator. To correct
  the conflicts, ArcMap Editor must be used for viewing the collisions and
  finalizing the reconciliation. In a future release, support is planned to permit
  MicroStation GeoGraphics to manage such reconciliation.

Again, this capturing and posting scenario will suit organizations that have elected
to keep their original data in DGN files that are managed within the AEC content
management platform. If modifications are required in the future, edits are made
in the original DGN file, which can subsequently be posted automatically to
the geodatabase. However, if modifications are permitted from any application
accessing the geodatabase, then the scenario in the following section should
be preferred.

Extract, Design, Post
Most AEC projects affect the status of infrastructure on the earth’s surface, and
ultimately need to be reflected in the geodatabase content. Once the project is
completed, the as-built
is documented and
maintained within the
Bentley user’s managed
environment. To permit
the geodatabase to
benefit from this content,
an update is required.
The update extracts
information from the
Bentley content manage-
ment system for posting
to the ArcGIS environment.

In this situation, a typical workflow would include the following steps:

• The first step is to extract the features to be updated. As explained previously,
  the connector extracts a selection of features in
  the area covered by the project. However, if the ultimate goal is to update the
  geodatabase with altered content, the update must absolutely be done with
  respect to the validation rules implemented within the geodatabase. For this



Bentley ArcGIS Connector                                                            7
  reason, the extraction will also include subtypes, attribute domains, and valida-
  tion rules as defined in the geodatabase. In the next figure, on the left is the
  ArcCatalog® Properties dialog for defining attribute domains, and on the right
  is a MicroStation GeoGraphics dialog used for editing the feature’s attributes.
• The second step is to modify the extracted features with the new information.
  In general, the level of detail of the information kept in the geodatabase will
  be less than the level of detail required for construction. For this reason, the
  user, as the subject-matter expert, will reference as-built designs and use the
  appropriate XFM tools to create new features (or extend existing features
  with the appropriate valid attributes).
• After the modified design is checked back into the Bentley content management
  system, the design can then be posted, as described in the preceding section.
  This post operation will create a new version that can be committed immediately
  if no conflicts occur, or reconciled with ArcMap Editor if required.

Automated Workflows
In typical organizations, planning and engineering professionals establish standards
and rules for creating and exchanging valid data, as well as workflows to make
work as productive and controlled as possible. The AEC content management
environment offers numerous functions for supporting the work of those profes-
sionals. In the case of the Bentley ArcGIS Connector, multiple extraction or post
operations can be automated in a schedule or can be triggered by an administrator.

For example, the landbase information required for an engineering project can
be extracted daily into hundreds of files to reflect the latest state of the geodata-
base. In the same sense, modifications from a MicroStation GeoGraphics user’s
department can be posted to the geodatabase every weekend. Also, the end of an
AEC project can trigger the update of the geodatabase with many new designs.

To support automated workflows, the AEC content management platform supports
the definition of connector jobs scheduled by day and time. The connector jobs
can include the designation of folders and files with directives for controlling
which files should be processed (for example, only those that have changed).

Reliability and performance have been key objectives in designing these connector
processes, to ensure that network or hardware failure does not result in invalid
data, as well as to permit processes to be restarted at the point they stopped.




Bentley ArcGIS Connector                                                            8
Development Tools
Bentley has used the latest technology in the ArcGIS Connector to ensure
productive and easy customization by both users and third parties.

The ArcGIS Connector consists of a series of three Web services, using the
SOAP protocol:

• Data extraction service
• Data posting service
• Schema maintenance service

Each of these services is written using the C# language in the .NET environment.
Where appropriate, events have been designed to allow for customization through
event handlers written in any .NET-compliant language. Integrated development
environments like Visual Studio .NET may then be used for development.

Each service is typically composed of multiple tasks. For example, the Data
Extraction service has the following tasks:

• Locking the appropriate document in ProjectWise,
• Extraction of the geodatabase content and translation into the DGN file, and
• File export of the resulting DGN file back into ProjectWise.

Since such a service
might be required for
hundreds of extractions
with exemplary reliability,
Bentley has developed an
Orchestration Framework
for supporting simultaneous
processing of multiple
tasks on multiple servers.
For example, if the Data
Extraction service, an
extraction task is extremely
demanding multiple
extraction tasks can be instantiated in parallel on different servers. To ensure
full reliability between those tasks, messages are gathered in persistent queues
so that the work state is not lost if a server fails. Also, to assist the administrator
in tuning the Orchestration Framework, an easy-to-use utility (shown below) is
offered for dispatching and monitoring the work on multiple servers.




Bentley ArcGIS Connector                                                              9
XML is also used wherever practical to ease customization and integration. For
example, all XFM Schema definition is based on XML, allowing the definition
of the features and attributes, validation rules, domain lists, placement rules, dialog
layout for editing attributes, and so forth. When features are created based upon
this schema and persisted in a DGN file, the attributes are kept, along with the
element in an XMLinDGN fragment. This approach allows any third-party
application to easily find and browse the attributes.

Conclusion
Providing true semantic interoperability, the ArcGIS Connector enables enter-
prise-oriented server-to-server workflows between the ESRI geodatabase and
the Bentley user’s managed environment. Workflow-driven data exchange
may be scheduled or event-driven.

The ArcGIS Connector is provided as a series of three Web services, using
the SOAP protocol and implemented in C# in the .NET environment, to
support extraction, posting, and schema maintenance. Integrated development
environments like Visual Studio .NET can then be used for customization and
further development.

Questions and requests for further information may be directed to:
www.bentley.com/aecgis.




Bentley ArcGIS Connector                                                                                                                          10

Bentley, the “B” Bentley logo, MicroStation, MicroStation GeoGraphics and ProjectWise are registered trademarks of Bentley Systems, Incorporated or
Bentley Software, Inc. ArcCatalog, ArcGIS, ArcMap, ArcSDE, are registered trademarks of ESRI. All other brands and product names are trademarks of
their respective owners. © 2003 Bentley Systems, Incorporated. Bentley Systems, Incorporated believes the information in this publication is accurate as
of its publication date. The information is subject to change without notice. BAA013260-1/0001 12/03

				
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