The ismart Suite Developing and Deploying Embedded Spatial Applications and Web Services in a Standard Enterprise IT Environment

Transcription

1 The ismart Suite Developing and Deploying Embedded Spatial Applications and Web Services in a Standard Enterprise IT Environment White Paper January 2004 espatial Incorporated

2 The ismart Suite Developing and Deploying Embedded Spatial Applications and Web Services in a Standard Enterprise IT Environment Abstract...3 Overview...4 Architecture Components...5 ismart Server Architecture...6 ismart Web Architecture...8 Interoperability...10 ismart Mobile...11 Enterprise Qualities of Service...11 Security and Firewalls...11 Database Layer Scalability...12 Application Server Layer Scalability...12 Client Side Scalability...12 Reliability...12 ismart Control Panel...12 Image Loading...12 The Feature Builder...13 Printing Support...13 Data Cleaning...13 Load Balancing and Management...14 Land Information Management System (LIMS)...14 Conclusion...15 espatial White Paper - ismart Suite Page 2

3 ABSTRACT This paper describes the architectural and functional characteristics of espatial technology, comprising a suite of software tools that represents a superior alternative for developing and deploying embedded-spatial applications to integration with traditional specialist GIS application packages. The two main components of the suite are the ismart Server and the accompanying ismart Web Designer development technology. ismart uses the Oracle Spatial database environment as its native data store, including spatial data. The espatial approach allows users to build and deploy embedded-spatial applications and web services in a standard enterprise IT environment at the database, application server, and web / web services tiers. Solutions can be deployed on any Oracle supported hardware platform and on any device that either provides a web browser or supports the Java Virtual Machine, thus providing full support for hand-held and mobile devices. espatial White Paper - ismart Suite Page 3

4 OVERVIEW In the past, spatial information was utilized within specialized applications and exclusively by expert high-end users. Recently, its integration within the widest range of business applications is becoming a common requirement. The prohibitive hurdles in achieving this integration are the difficulty, expense, and risk associated withdoing this using existing specialized geospatial information systems. To a large extent this is due to the specialized infrastructure used for these systems, the ensuing incompatible architectures with business systems, the difficulty in integration and the need for specialist skills. To solve this problem we need development and deployment tools specifically designed to embed spatial capabilities in business applications within standard COTS architectures and that provide ease of use for non-gis specialists and for rapid development. A core area for architectural compatibility is the data store. Traditional GIS applications store spatial and non-spatial data attributes separately. Typically, spatial properties of objects are stored in files that are managed by a file management system, while attribute data is stored in a commercial database (e.g., a relational database). This split design presents a significant difficulty in maintaining data integrity between spatial and attribute data, as the two types of data are not managed by the same engine. Oracle Spatial provides an information infrastructure that includes a single database system for managing both types of data, and a data structure that is independent of any particular application. This reduces the complexity of system development and management by eliminating the hybrid architecture of typical GIS data models, provides access to spatial information using industry standard SQL, and gives the ability to store spatial data in enterprise-wide database management systems which may be shared with additional enterprise applications. espatial s technology has been developed on this unified database environment. ismart dramatically enhances the functionality of an Oracle Spatial database by allowing real-time display, collection, editing, manipulation and query of spatial data using a standard Web browser without a specialized plug-in or download. Therefore, by utilizing espatial technology, Oracle Spatial users can enjoy a full range of advanced spatial data handling and management functions that are typically provided by specialized proprietary application packages. These functions, together with all data stored in the enterprise database, can be accessed from any PC or mobile device. This has been achieved by implementing all management information and spatial analysis functions in a standard enterprise (J2EE) application server, with support for standard web browsers and XML web services, in addition to distributed databases espatial White Paper - ismart Suite Page 4

5 and transactions, and high levels of security, scalability, and reliability. A pressing need relates to providing non-expert users with easy-to-use environments where they can visualize, query and manipulate spatial data without requiring any specific programming or database management background. To this purpose, additional tools and user-friendly environments to build and customize graphic user interfaces that facilitate interaction with the ismart platform have also been developed. Finally, an important concern for the design and development of contemporary and next-generation (web-based) information systems relates to interoperability issues. Interoperability refers to the capability of autonomous systems to exchange data and to handle processing requests by means of a common understanding of data and requests. espatial addresses this need through a variety of mechanisms for integration and interoperability with business and GIS applications, including common database environment, OpenGIS Consortium interoperability services and standards, web services capability, and Java components and APIs. The remainder of this paper is organized as follows. Section 2 describes the components of the ismart architecture. Main advantages of the architecture, including scalability and reliability are discussed in Section 3. Section 4 gives an overview of the additional tools that allow users to build and customize their applications using the ismart suite. Section 5 describes a case study, the Land Information Management System that has been developed for the Irish Department of Agriculture. Finally, Section 6 presents concluding remarks. ARCHITECTURE COMPONENTS In this section we describe the two major components of espatial technology, namely the ismart Server and the ismart Web Designer Development Environment, together with their architectural characteristics. ismart Web Designer allows software engineers to rapidly design, build, and deploy spatially-enabled Internet applications and services in a standard nonproprietary enterprise IT architecture. It therefore significantly reduces the overall system development and deployment costs. All ismart applications are standard J2EE application server applications and can espatial White Paper - ismart Suite Page 5

6 be developed without writing any client application code, and integrated with existing Internet applications. ismart Server Architecture The ismart Server architecture presents three main components: the User Interface Layer, the Application Server Layer, and the Database Layer (see Figure 6). Each component is described in the following sections. User Interface ismart provides a number of user interface components: A pure web user interface with no plug-in, download, or applet required. This user interface supports viewing, querying and redlining / basic editing of spatial data. This is built using standard Java Server Pages (JSP) with custom tag libraries (and unique web application framework) and so can easily be integrated with other applications. The user interface is presented on any Internet-connected device with a web browser including PCs and PDAs. A drop-in embedded spatial viewer and editor component. This is a Java applet, but can be integrated with Windows and Oracle Forms applications as well as in web pages and Java applications. This enables spatial viewing, querying, and richer editing capabilities to be easily embedded in desktop and web applications. database). Offline / Occasionally Connected Use: The ismart Editor is able to work disconnected from the server, viewing and editing off-line files generated from the server, and synchronizing changes back to the server (and thus the Oracle Spatial Application Server Layer The application server layer is built as a J2EE application, with several EJB modules, to provide server-centric spatial functions to applications. Key components of the server (implemented as EJBs) are: User Interface & Interoperability services (addressed in more detail later in this paper) espatial White Paper - ismart Suite Page 6

7 Geospatial functions for viewing, layer selection, editing, querying, analysis Data Source Management for multiple databases and types of data store (Oracle Spatial, OpenGIS WMS, Live Sources, and other custom sources) Spatial Cache with support for clustering, editing / modification monitoring on the database, and distributed transactions Use of J2EE services for clustering, security, transactions, Configuration, Layer & Data Set-up, and Layer rendition-style definition Java API (via stateless session bean EJB) to access all server functions from any Java application server or client Database Layer The database has the following distinct features: 1. Spatial Server Metadata: Since the spatial Server is a generic tool to display spatial information from any table that contains Oracle spatial data columns or Oracle Intermedia images, it requires some information on where it can find these objects and images and how it should access them. This information is stored in the Server metadata tables. This has the benefit that data to be used with ismart Server need not be in any pre-determined schema. 2. Smart Symbols are representations of network components. These symbol components combine the graphical representations to an internal state representation for the symbol. The internal state consists of the following: Port Location. A port is a location where outside connections are allowed to the symbol. These ports exist at certain locations on the symbol. Internal Connectivity. These connections model the internal connections between the ports on the symbol. These connections have a number of properties, such as: Open / Closed mask. A flag to indicate the state of the connection Network mask. A mask to indicate which network types are supported by this connection. In a number of applications more than one network is using the same physical wires. TV networks have TV signal, cable modem signals and power all running over the same networks and through the same components. 3. Spatial Topology: The spatial topology package builds and maintains a topology model in the database for the spatial objects. This topology is built espatial White Paper - ismart Suite Page 7

8 and maintained from the geometry objects in a specified source table. Functions include: Bulk Topology creation from existing tables containing Oracle Spatial objects. This function allows topology to be built from existing data. Dynamic Topology functions handle changes in the topology when elements in the base table are created, modified or deleted. To ensure data consistency this is usually handled via database triggers, but other custom approaches are possible, depending on the application s needs. The database topology engine consists of a collection of Oracle database tables and stored procedures written in Java that run inside the Oracle Aurora Virtual Machine. This way, all functions and procedures have fast and efficient access to the information stored inside the database without adding to the network overhead. These functions can be accessed via PL/SQL wrapper code. PL/SQL is the procedural extension of SQL defined by Oracle. The topology system can be configured to combine multiple sources or parts of different sources into a topology layer. Other features are: Multiple topology layers. The system is not limited to just one topology. The system supports an unlimited number of topologies. Client independent. Whatever desktop software is being used to edit the spatial data, topology and connectivity are maintained automatically inside the database. ismart Web Architecture The ismart Web Designer development environment is considered with respect to Web Tier and the ismart middle tier. Web Tier User Interfaces are built as web pages using standard web pages using standard web page layout tools such as Macromedia DreamWeaver, incorporating Custom Tags provided by ismart for spatial viewing, editing, manipulation, and analysis. espatial White Paper - ismart Suite Page 8

9 ismart Web Middle Tier ismart Web provides a unique run-time framework that extends Java Server Pages (JSP) with a framework to handle session context data, actions & events, interaction rules, and stored SQL queries, with no Java coding required by the developer. This greatly simplifies and adds to the power of JSP. It exposes all the capabilities of the ismart Server. ismart Server uses an enterprise Java (J2EE) application server, such as Oracle 9iAS, SunONE Application Server, BEA WebLogic, or IBM WebSphere. General JSP applications have the following issues: There is no capability for wiring session data to controls on Web pages, nor more general form handling such as validation rules There is no event model to decouple the user events on a web page from the actions and user interface flow resulting from those events Java / JSP code must be written to handle user interaction rules (i.e., sequences of actions as results of user interface events) It is generally necessary to write several JSP pages for one web page to handle the user actions on the web page, or to avoid this, make the JSP page parameter driven and more complex. This may result in many JSP pages per displayed web page. To structure session context data (by having data objects), JavaBeans need to be written Jakarta STRUTS addresses some of the above problems but is complex and requires significant knowledge of the servlet and JSP specifications and Java coding. The unique ismart Web JSP framework removes all of the above problems, without requiring Java coding. It greatly reduces the effort, skill, and complexity (for maintenance and reliability) of JSP applications while still using a standard JSP environment. ismart Web provides: Custom tags HTML-like tags that may be incorporated into web pages to process forms and call actions, queries and ismart Server functions A JSP framework to handle forms, validation, events & actions, session context data, interaction rules (actions), and named SQL queries (All of these are stored as XML files on the application server) espatial White Paper - ismart Suite Page 9

10 Smart Web controls that can be incorporated into web pages, and are wired automatically by the framework to actions (e.g., a button), queries, or session context data (e.g., a text field) An Integrated Development Environment (IDE) to define for applications: session context data; interaction rules (actions and control flow); and named SQL queries Support for Spatial SQL queries, including spatial results and parameters Interoperability Figure 5. Screenshot of user application under construction in DreamWeaver ismart provides a variety of interfaces to provide for integration and interoperability with business and GIS applications. Key mechanisms are: Common database environment: Specifications on spatial entities and the space / time reference systems have been provided by the OpenGIS Consortium. The data model used by ismart is the Oracle Spatial object-relational model. This model corresponds to the SQL with Geometry Types implementation of spatial feature tables described in the OpenGIS ODBC/SQL specifications for geospatial features. OpenGIS Consortium interoperability services and standards: The ismart suite implements other OpenGIS interoperability standards: Web Mapping Services (WMS) to display map layers from other GIS applications, and allow other applications to display map layers from ismart Geography Markup Language (GML) a common XML-based file format for exchanging spatial information and attributes. Web services Leveraging its use of standard enterprise application server technologies, ismart provides easy mechanisms to build and use web services with embedded d spatial services. Java components and APIs to easily embed spatial capabilities in business applications built using standard technologies and architectures. espatial White Paper - ismart Suite Page 10

11 ismart Mobile The ismart Suite also provides ismart Mobile - for occasionally connected mobile use, with synchronization of redlining and digitizing back to ismart server. As a consequence spatial data can be delivered to practically any device, anywhere. It supports both viewing and editing of spatial data. ismart Mobile is completely customizable and can be deployed as an applet inside a Web page or as a windows application. The ismart Mobile capability provides: Full-screen Viewer / Simple Editor: Toolbar, menus, dialogs, drop-down lists of features to digitize Layer control, search functions, symbols and connections, and client topology check Ability to generate off-line files for disconnected use and to synchronize collected, edited, or updated data ENTERPRISE QUALITIES OF SERVICE Security and Firewalls ismart leverages the J2EE security model. This enables user-level authentication and authorization (AA) against databases and password files. More comprehensive AA is available via the J2EE Java Authentication Authorization and Security (JAAS) API. The JAAS is based on the UNIX Pluggable Authentication Module (PAM) and provides for multi-layered AA that can include LDAP / JNDI domains, NT security domains, Solaris / Unix security domains as well as physical security tokens such as smart cards. ismart can support user-level database security enhancements such as presenting on-demand user-level views of data as well as Oracle LABEL (row-level) security. This allows fine-grained security policies to be implemented at the data level. By default, applications are deployed over HTTP. ismart does allow a secure HTTPS connection to be set-up between the user s browser and the web-server, with clients authenticating the web-server. A typical secure deployment of ismart involves three firewalls, with web server in a DMZ ( de-militarized zone ) behind an external firewall, application server behind next first internal firewall, and databases and other applications behind second internal firewall. ISMART may also be deployed in a variety of other configurations, including two firewalls. espatial White Paper - ismart Suite Page 11

12 Database Layer Scalability ismart can access user-based information across a number of different databases. Similarly, the Server transparently supports the display of graphical data from different databases. Each individual database server could thus be optimized for the data it controls. Application Server Layer Scalability The application server layer can be scaled in a number of ways. In its most advanced form, the application server supports the creation of a single virtual application server that is built across a number of physical machines. The application server then handles all the load balancing and connection issues arising from this set-up. Alternatively a number of parallel application servers could be created and the user connections can be distributed across those machines. Scaling of web servers is also supported. Client Side Scalability ismart requires no plug-in or down-load on the browser for Geospatial web applications. Any client with a web browser may be used: desktop machine, laptop, PDA, etc. An applet is provided for occasionally connected mobile use. Reliability To ensure reliability for the database layer, Oracle s fail-safe mechanisms are utilized. Parallel server technologies can also be used. The J2EE application server handles fail-over between nodes transparently and hence controls application server reliability. ISMART CONTROL PANEL ismart includes a Control Panel tool for facilitating the building of applications that exploit spatially-enabled datasets. The capabilities of this tool are particularly useful for non-expert programmers as they allow the creation of features together with their symbology, the importing of digital imagery and incorporate the drag-and-drop methodology to graphical user interface design. Image Loading The Control Panel incorporates an Image Loader utility designed to load scanned aerial / satellite photos and topographic maps into the database (see Figure 7). The loaded imagery is then available for heads up digitizing. This image loading utility follows the long standing approach to digital image handling within existing dedicated image processing systems, by pre-processing the image data into multi-resolution representations [3]. The idea is to eliminate the need espatial White Paper - ismart Suite Page 12

13 to resample the image at run time by loading the best-fit resolution image to the zoom factor currently active within the web browser. ismart advances this trend by further subdividing the individual reduced resolution image files into tiles of a pre-defined pixel size. Thus, when a web browser is viewing a particular geographic location, only those individual tiles at the requested zoom factor will be physically sent over the network and not the entire image file. This, of course, is essential to real-time viewing of digital imagery due to their inherent size restrictions. For example, a typical black &white aerial photo scanned at 30_m (850dpi) resolution requires approximately 60Mb of disk space (uncompressed) [6]. Color imagery, of course at the same scanning resolution, will require three times as much space, i.e., 60Mb for each of the three color bands; red, green, and blue. The Feature Builder The Feature Builder allows users to define new data sources and the feature classes that the source controls (see Figure 8). All feature characteristics (e.g., color, weight, pattern, etc.) are defined using this utility. Also incorporated within the Feature Builder is the capability to add events to specific feature digitizing operations. For example, in a land parcel application, when a "Property Centroid" feature is first digitized, an event can be associated with this operation that calls a pre-defined SQL query to populate the "Property ID" column in the user attribute "Property" table, and subsequently displays this attribute value as the centroid label text in the graphics. Alternatively, if a Property Centroid is deleted, a SQL query previously attached as an event to this type of an operation (on this type of feature) can delete all the user attributes associated with this centroid feature. Printing Support Batch printing is supported through programmatic control of printing from the server. Maps are built straight from the Oracle Spatial database and delivered to the printer on a client machine or the server. This approach allows the system to print any given area (or set of areas that meet with certain criteria) that the client requests without ever having to view that area. A GUI is provided to layout Plot templates. Data Cleaning ismart topology fix facility enables imported data to be automatically checked for common digitizing errors such as gaps, dangles, duplicate linework, thinning errors and splits. This process helps to deliver clean unambiguous data ready for use in enterprise spatial systems. espatial White Paper - ismart Suite Page 13

14 Load Balancing and Management The ismart Server Load Tester automates the identification of bottlenecks in system performance caused by hardware or database errors or network functionality. LAND INFORMATION MANAGEMENT SYSTEM (LIMS) In this section, we describe one of the applications implemented using ismart. The LIMS application, (known as imap), developed for the Irish Department of Agriculture, utilizes the Spatial Server platform to deliver a spatially-enabled Internet solution for the tracking and management of land information based on land usage, land classifications and land ownership changes over time. Figure 6 is a screenshot of such an application as viewed on a standard web browser. Figure 6. The Land Management Information System viewed on a standard web browser The land information management system provides a seamless Oracle 9i Spatial database environment for the combination of multiple land information datasets. Integrated database topology ensures the integrity of the topology relationships within the spatial database. The normal edit (i.e., create, modify, and delete) and spatial analysis functions associated with a traditional GIS based land management applications, are deployed as Java stored procedures in the Oracle Spatial database. The implemented functionality includes: Vector data manipulation (pan, scroll, zoom, locate, window queries, etc.) Vector and attribute data entry and editing Spatial and attribute data analysis (polygon overlay and network tracing) Thematic mapping (display of query results with assigned symbology) Raster/Vector integration espatial White Paper - ismart Suite Page 14

15 CONCLUSION This paper presents a revolutionary technology that extends Oracle Spatial databases by adding server-centric spatial information management functionality that can be used within web-enabled applications accessed via any device that supports web browsers or the Java Virtual Machine, e.g., standard PC and PDA. A major advantage of this technology is that it does not require the use of complex GIS specialist application specific software or skill. The ismart approach allows users to build and deploy embedded-spatial business applications integrating with standard enterprise IT environment at the database, application server, and web / web services tiers. This greatly reduces the effort, specialist skills, and risk of embedding spatial capabilities in applications, while significantly enhancing the capabilities, depth of integration, performance and reliability of such applications. Furthermore, typically no application code is installed on the client side, nor is any download or plug-in required, which leads to the most economical usage of bandwidth and resources for real-time response, and also avoids IT issues with client set-up compatibility for particular plug-ins or applets. Support is also provided for off-line / occasionally connected use via a drop-in spatial editing and viewing component. Another advantage of the espatial technology relates to its ease of use. Indeed, it includes a user-friendly environment that allows building and customizing the application by means of a graphical tool without requiring any particular programming skill. In this way, even non-expert users can easily build a spatially enabled application. Lastly, a variety of mechanisms are supported for integration and interoperability with business and GIS applications, including common database environment, OpenGIS Consortium interoperability services and standards, web services capability, and Java components and APIs. espatial White Paper - ismart Suite Page 15

16 FOR MORE INFORMATION Contact for more information on our ismart Suite. espatial Solutions, Ltd Corporate Headquarters Jabil Building Clonshaugh Industrial Estate Dublin, Ireland espatial, Incorporated U.S.A. Headquarters 2325 Dulles Corner Blvd. Herndon, VA Inquiries: espatial Fax For more information on ismart Suite and Implementation Services contact: Author: Eamon Walsh, et al. October 2003 All Rights Reserved. This document is provided for informational purposes only and the information herein is subject to change without notice. Please report any errors herein to espatial, Inc. The marks espatial and ismart are trademarks of espatial Solutions Limited. Use of these trademarks in any form, or in a descriptive or generic context, without the express consent of espatial Solutions Limited is strictly prohibited. All other company and product names mentioned are used for identification purposes only and may be trademarks of their respective owners. espatial White Paper - ismart Suite Page 16