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 geodatabase. 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. 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 ). 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. 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 information 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. 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 coverages 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 system of the geodatabase content is also recognized, and can be reprojected to the coordinate system enforced in the engineering project. 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? 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. 6
Alternatively, the 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 management 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 7
reason, the extraction will also include subtypes, attribute domains, and validation 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 professionals. In the case of the, 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 geodatabase. 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. 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. 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 enterprise-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. 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