GIS Software Technology – 27th Edition (Spring 2010)

GIS Software Technology – 27th Edition (Spring 2010)

Since the early 1970s, ESRI has continued to develop evolving GIS software technology supporting functional requirements identified by the GIS user community. Sensitivity to software development trends and enterprise architecture strategies provide guidelines for development investment. ESRI software developers leverage the latest computer hardware and software technology to maintain ESRI's leadership in the GIS marketplace. ESRI aligns its resources to provide the best software and services based on GIS customer needs.

This section provides an overview of the ESRI software and associated product technologies. Understanding the primary role of each member of the ESRI software family will help users identify technology needs and develop a road map for migration to successful enterprise GIS operations.

GIS Software Evolution
Figure 2-1 provides an overview of the ESRI software history and the associated third-party technologies supporting operational GIS enterprise environments.



The early ARC/INFO software provided developers and professional GIS users with a rich toolkit to support geospatial query and analysis and demonstrate the value of GIS technology. ArcView introduced easy-to-use commercial off-the-shelf (COTS) software that could be used directly by GIS operational users. Map Objects empowered developers with a simple way to integrate GIS in common standard application environments. Terminal servers provide remote user access to centrally managed GIS desktop applications. ArcIMS Web services introduced a framework for publishing GIS information products to Web browser clients. ArcStorm and ArcSDE introduced better ways to manage and support GIS data resources.

Hardware performance improvements led to more efficient programming techniques deployed in the late 1990s. ArcGIS Desktop software provides users with a simple and powerful GIS application interface to support standard operations. ArcGIS Server and ArcGIS Engine provide GIS developers with rich processing tools and full GIS functionality for custom application development and deployment. Distributed geodatabase management tools and replication services support remote user access to centrally managed spatial resources and provide better protection and sharing of geospatial data.

Web technology introduced more ways to share data and services, enabling a new services oriented component architecture along with interoperability standards that provide open and adaptive solutions developed from a multi-vendor component architecture. Google and Microsoft introduced pre-processed (cached) online global basemap imagery providing free access to geography from home and our mobile devices. Online data and services become an important extension of our GIS user experience. Rich internet client technology improves display performance system scalability optimizing integration of distributed Web services and data sources. Hardware virtualization and cloud computing provide simpler ways to administer and support GIS applications and services.

Software technology migration from scripts to objects to services accelerated technology change while increasing demands on hardware performance and network connectivity. The change in technology impacted business processes in an evolutionary way opening new opportunities for GIS to support enterprise and community operations, helping customers better understand their world and make more informed decisions.

Read more about GIS software evolution.

GIS Architecture Evolution
Many ESRI customers developed effective enterprise solutions with the Workstation ARC/INFO and ArcView GIS software provided in the 1990s. The current ArcGIS software provides operational capabilities that were not available with the older technology. Most ESRI legacy customers have migrated their data and applications to the current ArcGIS object-based geodatabase technology. New customers support enterprise GIS solutions directly with ArcGIS desktop and server software.

This past year saw some remarkable gains in performance and scalability of ArcGIS Server software. ArcGIS 9.3.1 introduced a new map service description (MSD) document with a new graphics rendering engine, new optimize mapping tools, and worldwide access to high quality cached image base maps. ArcGIS Online, new Resource Centers, and a growing number of ESRI User Forums expand and connect the GIS user community on a global scale. This was a remarkable year for GIS performance and scalability, with hardware performance gains of over 70 percent and software reducing processing loads by over 50 percent, expanding entry level GIS software capacity to over four times what was available just one year ago.

Technology is Changing GIS user Productivity
User performance expectations are changing. GIS user average map display performance was over 70 seconds in 1992, with geographic analyst bragging about how this used to take them a week to product the same map product without computers. By 1999 these same map displays were rendered withint 7 seconds. Figure 2.2 shows the change in typical light map display response time during the 1990s.

GIS user productivity continued to improve over the last 10 years. Web mapping was introduced as a way to share geographic information products throughout the organization and with the public. GIS distribution options continued to expand over the past few year, with dynamic services generated within seconds and increasing popularity for preprocessed map products from distributed cached map services. Higher quality heavier map displays are now more popular with quick display response times and broadband Internet connectivity. Figure 2.3 shows the change in light and medium map display response times over the past 10 years.

GIS Technology Alternatives
Current GIS technology is available to support a rapidly expanding spectrum of GIS user needs. Solutions are supported by ESRI products integrated with a variety of vendor technologies. Data storage and data management technologies are growing in importance as organizations continue to develop and maintain larger volumes of GIS data. Individual server storage solutions are being replaced by more adaptive storage area networks (SANs), enhancing the IT's ability to respond to changing data storage needs and providing options for efficiently managing large volumes of data. GIS data sources include file servers, geodatabase servers, and a variety of business database solutions. Desktop ArcGIS applications can be supported on local workstation clients or on centrally managed Windows Terminal Server farms.

Web services are supported by ArcGIS Server and legacy ArcIMS mapping services to Web browser clients throughout the organization and the community. ArcGIS clients are able to connect to ArcGIS Server Web products as intelligent browser clients, enabling connection to unlimited data resources through the ESRI Geography Network as well as organization resources served through a variety of ESRI customer portals. Users can access applications from the Internet or through intranet communication channels. Mobile ArcGIS users can be integrated into central workflow environments to support seamless integrated operations over wireless or remote connected communication. ArcGIS Desktop applications can include Web services as data sources integrated with local geodatabase or file data sources, expanding desktop operations to include available Internet data sources. GIS enterprise architecture is typically supported by a combination of ArcGIS Desktop, ArcGIS Server, and geodatabase software technology. Selecting the right combination of technology will make a big difference in the level of support for user operational needs and business productivity.

GIS Configuration Alternatives
GIS environments commonly begin with single-user workstations at a department level within the organization. Many organizations start with one GIS manager and evolve from a department level to an enterprise operation. This was common through the early 1990s, as many organizations worked to establish digital representation of their spatial data. Once this data is available, organizations expand their GIS operations to support enterprise business needs.

GIS is a very compute-intensive and data-rich technology. A typical GIS workflow can generate a remote user desktop display every 6–10 seconds with a client application requiring hundreds of sequential data requests to a shared central data server to support each desktop display. GIS workflows can place high processing demands on central servers and generate a relatively high volume of network traffic. Selecting the right configuration strategy can make a significant impact on user productivity.

Data can be shared between users in a variety of ways. Most organizations today have user workstations connected to local area network (LAN) environments and locate shared spatial data on dedicated server platforms. User applications connect to shared data sources to support GIS operations.

Centralized Data Configuration Alternative
The most simple system architecture is supported by a central GIS database. A central database architecture supports one copy of the production database environment, minimizing administrative management requirements and ensuring data integrity. GIS desktop applications can be supported on user workstations located on the central LAN, each with access to central GIS data sources. Data sources can include GIS file servers, geodatabase servers, and related attribute data sources as shown in figure 2-4.

Remote user access to central data sources can be supported by central Windows Terminal Server (WTS) farms, providing low-bandwidth display and control of central application environments.

Centralized application farms minimize administration requirements and simplify application deployment and support throughout the organization. Source data is retained within the central computer facility, improving security and simplifying backup requirements. A variety of ArcIMS map services can support standard browser clients throughout the organization. Web mapping services support low-bandwidth access to published GIS information products and services.

Today distributed computing technology can support consolidated architectures at a much lower risk and cost than similar distributed environments. For this reason, many organizations are in the process of consolidating their data and server resources. GIS can benefit from consolidation for many of the same reasons experienced by other enterprise business solutions. Centralized GIS architectures are generally easier to deploy, manage, and support than distributed architectures and provide the same user performance and functionality.

Distributed Data Configuration Alternative
Distributed solutions are supported by replicated copies of the data at remote locations, establishing local processing nodes that must be maintained consistent with the central database environment as shown in figure 2-5. Data integrity is critical in this type of environment, requiring controlled procedures with appropriate commit logic to ensure changes are replicated to the associated data servers.

Distributed database environments generally increase initial system cost (more hardware and database software requirements) and demand additional ongoing system administration and system maintenance requirements. Distributed solutions are provided to support specific user needs. These generally increase system complexity and cost and lengthen system deployment timelines.

In many cases, standard database solutions do not support replication of spatial data. GIS users with distributed database requirements must modify their data models and establish procedures to administratively support data replication. The complexity of current geodatabase environments has complicated the implementation of an efficient commercial spatial replication solution. Many GIS users are interested in replicating regional or selected versions of a geodatabase, which is not understood by commercial replication technologies. ArcGIS software functions are available to support custom geodatabase replication solutions. ArcGIS 9.2 provides support for distributed geodatabase replication, providing alternative options for supporting distributed operational requirements.

Expanding GIS Technology Trends
GIS software and computer infrastructure technology continue to expand capabilities and introduce new business opportunities. GIS is expanding to support mobile, federated, and service-oriented GIS operations.

Mobile GIS Technology
Organizations are expanding operations to incorporate mobile users as an integral part of their enterprise workflow. Improved availability and capacity of wireless technology support mobile communication connectivity for a growing number of GIS users.

Figure 2-6 provides a simple overview of common ArcGIS deployment alternatives. Traditional department-level GIS client/server operations are looking for ways to improve access and data sharing with other organizations and introducing new emerging federated GIS architecture strategies. Traditional enterprise-level operations are looking for ways to integrate GIS with other centrally managed business operations and introducing new emerging integrated business solutions based on service-oriented architecture strategies.

Federated GIS Technology
Database and Web technology standards provide new opportunities to better manage and support user access to a rapidly growing volume of geospatial data resources. Web services and rich XML communication protocols support efficient data migration between distributed databases and storage locations. Web search engines and standard Web mapping services support integrated geospatial information products published from a common portal environment with data provided from a variety of distributed service locations. Federated architectures identified in figure 2-7 promote better data management, integrating community and national GIS operations. Geodatabase replication services and managed extract transform, and load (ETL) processes support loosely coupled distributed geodatabase environments.



Service-Oriented Architecture
Technology is changing faster each year, and organizations are searching for more effective ways to manage technology change. During the 1990s, there was a shift in programming methods promoted by commercial software acceptance of component architecture standards. Software development migrated from compiled, scripted legacy languages to object-based programming environments. ArcGIS technology is based on common ArcObjects components used to support a broad range of desktop and server software. Developing new applications and functionality in an object-based programming environment is much more powerful than developing in the traditional scripted software languages.

Technology change is again being influenced by general acceptance of standard Web communication protocols and more stable and available network bandwidth connectivity. Software development is taking advantage of Internet communication standards and network connectivity with a new service-oriented enterprise architecture strategy.

The core components supporting a service-oriented architecture (SOA) are presented in figure 2-8. These components include service providers, service consumers, and implementation of a service directory.

Common Web protocols and network connectivity are essential to support this type of architecture. Business functions are encapsulated as Web services that can be consumed by Web clients and desktop applications.

The basic language of an SOA is introduced in figure 2-9. New business functions are provided as Web services, which are IT assets that correspond to real-world business activities or recognizable business functions, in which accessibility is based on service policies established to support enterprise operations (loosely coupled to the business applications).

From a technical perspective, services are coarse-grained, reusable IT assets. They have well-defined interfaces (service contracts) with the software technology providing the service abstracted from the external accessible service interface. The trend is to support SOA through Web services based on SOAP and XML.

The SOA infrastructure connects service consumers with service providers, may be used to communicate with service directories, and may be implemented using a variety of technologies.

Business environments are influenced by the rate of technology change. Change introduces risk contributing to business success or failure. Selecting the right technology investment strategies is critical. Service-oriented architecture deployment strategies reduce business risk through diversification and reduced vendor dependence. Open standards reduce the time and effort involved in developing integrated business systems, providing integrated information products (common operating picture) that support more informed business decisions. Advantages of a service-oriented architecture are highlighted in figure 2-10.



ESRI embraced open standards during the 1990s and has actively participated in the Open GIS Consortium and a variety of other standards bodies in an effort to promote open GIS technology. The initial ArcIMS Web services, Geography Network metadata search engines, Geospatial One-Stop, and the ESRI Portal Toolkit technology are all examples of service-oriented solutions supporting ESRI's current customer implementations. Figure 2-11 provides a view of how current ESRI software supports the evolving SOA enterprise infrastructure.



The SOA framework includes multiple access layers connecting producers and consumers, based on current client/software technology and incorporating Web application and service communication tiers. Consumers connect to producers through a variety of communication paths. This framework supports a presentation tier of viewers with access to available published services, a serving/publishing tier of services, and an authoring tier of professional ArcGIS Desktop users. This framework supports current client/server connections (client applications), Web applications, and Web services—all available today with current technology. Future vendor compliance and maturity of Web interface standards are expected to gradually migrate business applications from tightly coupled proprietary client/server environments to a more loosely coupled service-oriented architecture. The ideal environment would decouple business services and workflows from the underlying software technology providing an adaptive business environment that can effectively manage and take advantage of rapid technology change.

GIS is by nature a service-oriented technology with inherent fundamental characteristics that bring diverse information systems together to support real-world decisions. GIS technology flourishes in a data-rich environment, and ArcGIS technology can help ease the transition from existing "stovepipe" GIS environments. The geodatabase technology provides a spatial framework for establishing and managing integrated business operations. Many spatial data resources are available to support organizations as they migrate their operations to take advantage of GIS technology.

Migration toward a service-oriented architecture is more a change in attitude than a change in technology. Moving a business from high-risk, tightly coupled, monolithic stovepipe operations to a more integrated responsive service-oriented architecture will take time. Figure 2-12 provides some basic guidelines for moving existing systems to a more dynamic and supportable SOA environment.



Understanding SOA and how it enables business process integration and helps control and manage technology change is important. Organizations must build an infrastructure that can effectively take advantage of new technology to stay competitive and productive in today's rapidly changing environment.



ESRI Product Family
The ESRI product family, illustrated in figure 2-13, includes a mix of software developed to support a full range of GIS user requirements. GIS software is provided to support desktop, server, and mobile user operations. Data management solutions are provided to support data file, geodatabase, and Extensible Markup Language (XML) based formats.

GIS Web services are provided by ESRI to support a variety of managed, hosted, and shared GIS Internet services. Online resource centers, templates, forums, Web map hosting, collaboration, and global map cache all make ArcGIS Online a growing part of enterprise GIS core technology. ArcGIS Server provides technology for publishing GIS services that can be consumed by ArcGIS Desktop, mobile GIS, and standard Web browsers. HTML JavaScript and new Internet Rich Clients (Adobe Flex and Microsoft Silverlight) provide users with high map quality and improved user display performance over the Web. ESRI Developer Network (EDN) provides a range of technical services to the ESRI developer community through a bundled low-cost developer software license.



ArcGIS Desktop Software Solutions
Figure 2-14 provides an overview of the primary ArcGIS Desktop client operations. Potential candidate workflows support standalone Desktop, connected Desktop, and centralized Desktop configurations.

Standalone ArcGIS Desktop workstation. ArcGIS Desktop workflows can operate as a single standalone workstation using a variety of local data sources. The personal geodatabase is now supported by a Microsoft SQL Server Express database (name was changed this year to Desktop Geodatabase), which can operate as a replica version of a central ArcSDE geodatabase. The SQL Server Express database will support up to 4 GB or geospatial vector data. The ArcGIS Desktop workstation can also support a File Geodatabase, which provides up to 1 TB of data per data file. The File Geodatabase can provide a replica of reference data layers that can be incrementally updated from a central ArcSDE geodatabase.

Connected ArcGIS Desktop workstation. ArcGIS Desktop user workflows can operate in a connected local area network (LAN). Standard architectures include ArcGIS Desktop workstations connected over a LAN to a central ArcSDE geodatabase, Web services, and Image data sources (ArcGIS Server Image Extension was introduced this year as the new name for Image Server as it is integrated into the ArcGIS Server core software.

Centralized ArcGIS Desktop server. ArcGIS Desktop user workflows can use terminal clients to access centrally managed ArcGIS Desktop applications. ArcGIS Desktop can be deployed on Windows Terminal Server using Microsoft or Citrix terminal clients. Most ESRI clients use Citrix XenApp terminal clients for optimum compute and display performance.  ArcGIS Desktop Workflow Patterns. ArcGIS Desktop workflow performance targets can be generated from the CPT Calculator tab. ArcGIS Desktop software technology selections include workstation (wkstn) and Windows Terminal Server (WTS Citrix) workflow architecture patterns. All ArcGIS Desktop workflows use an MXD map document. Light, medium light, medium, medium heavy, and heavy display complexity settings generate a full range of potential workflow performance targets. Figure 2-15 shows the ArcGIS Desktop software technology selections available with the CPT Calculator tab.  Calculator Workflow Nomenclature. The CPT Calculator generates a workflow name that identifies the selected Software Technology and Performance Parameters. Changes in the software performance parameters will change the workflow performance targets based on performance technology baselines and key performance parameters established from ESRI benchmark testing. The System Design Strategies Software Performance chapter will provide more information on establishing appropriate workflow performance targets and building high performance GIS applications and services. Figure 2-16 provides an overview of the CPT Calculator workflow nomenclature.  ArcGIS Desktop Standard ESRI Workflows. The most common ArcGIS Desktop workflow patterns are generated from the Calculator tab and listed in the Standard ESRI Workflow section of the CPT Workflow tab. The Workflow tab is the performance target lookup table used for Capacity Planning Design. ArcGIS Desktop workflows include light and medium complexity performance targets for both workstation and terminal server architecture patterns. Citrix terminal server workflows include both vector only and raster image display density, a performance factor that impacts terminal client display traffic. Figure 2-17 provides an overview of the ArcGIS Desktop Standard ESRI Workflow selections.  ArcGIS Desktop Performance. The ArcGIS Desktop workflow performance will vary based on complexity and data source. Figure 2-18 provides a Workflow Performance Summary that shows ArcGIS Desktop light and medium complexity workflows for workstation and Windows Terminal Server deployment. Workstation display response times are based on workstation 100 Mbps network interface connections. Windows terminal client connections are based on T-1 (1.5 Mbps) WAN bandwidth. Workflow Performance Summary includes a full range of dynamic data sources available in the CPT Design tab (SDE_DBMS, small and large File GDB, small and large Shape File.



Mobile GIS
Mobile GIS supports a range of mobile systems from lightweight devices to PDAs, laptops, and Tablet PCs. ArcPad is software for mobile GIS and field-mapping applications. All ArcGIS Desktop products—ArcReader, ArcView, ArcEditor, and ArcInfo—and custom applications can be used on high-end mobile systems such as laptops and Tablet PCs. Figure 2-19 provides an overview of the primary connected mobile workflow alternatives.

ArcGIS Desktop Disconnected Operations. The ArcGIS Server Basic license supports distributed geodatabase replication. Geodatabase replication provides loosely connected synchronization services for distributed geodatabase versions maintained in supported database platforms. Web-based disconnected check-in and checkout services are also provided. Distributed geodatabase replication is discussed later in Data Administration.

ArcGIS also provides geodatabase support in a Microsoft SQL Server Express personal database. Microsoft SQL Server Express is bundled with each ArcGIS Desktop software license. ArcGIS Desktop clients (including custom ArcGIS Engine runtime deployments) can support a distributed geodatabase client replica and synchronize changes with the central parent geodatabase. The SQL Server Express database has a data capacity of 4 gigabyte (GB).

ArcGIS also supports a file based geodatabase. The ArcGIS Server 9.3 data checkout/check-in and one-way incremental replication Web interface supports distributed file geodatabase clients. A file geodatabase can support up to 1 TB of data with impressive performance (single use performance comparable to an ArcSDE Geodatabase experience).

ArcPAD Mobile Operations. ArcPAD supports checkout of ArcGIS Desktop map document to a local device shape file for field operations. Changes to the mobile shape file can be made during disconnected operations. An ArcGIS Desktop check in process compares changes made while disconnect and generates changes tables to integrate with the Enterprise geodatabase.

ArcGIS Mobile. ArcGIS Server Advanced license supports ArcGIS mobile software development kit. ArcGIS Mobile lets developers create centrally managed, high-performance, GIS-focused applications for mobile clients. Mobile applications powered by ArcGIS Server contribute to increased field productivity and more informed personnel.

ESRI Standard Workflows The most common ArcGIS Mobile workflow patterns are generated from the Calculator tab and listed in the Standard ESRI Workflow section of the CPT Workflow tab. ArcGIS Desktop clients can operate as mobile stand alone workstations. ArcGIS Mobile workflows include the ArcGIS Mobile Client, the Mobile Synchronization Service and the Mobile Provisioning Service. Figure 2-17 provides an overview of the ArcGIS Mobile Standard ESRI Workflow selections.

Mobile Workflow Description. The ArcGIS Mobile workflow patterns used for the Standard ESRI Workflows are documented in the Workflow Description section using the Calculator nomenclature. The ArcGIS Mobile client workflow uses an MXD Light complexity 100% dynamic vector only 400x300 pixel display. The Mobile Synchronization Services uses a SOAP MXD light complexity 10% Dynamic (limited to exchanging updated features streamed to client over SOAP interchange) with 400x300 Display. Mobile provisioning service downloads 100% of the Dynamic MXD display over a SOAP connection. Figure 2-21 provides the description of the Mobile workflow calculator performance selection.  Mobile Workflow Performance. Figure 2-18 provides a Workflow Performance Summary for the light and medium ArcGIS Desktop stand alone workflows (SDE_DBMS and small File GD data source options) and the ArcGIS Mobile client, synchronization service, and provisioning service performance profiles.



ArcGIS Server Web Operations
Figure 2-23 provides an overview of the primary ArcGIS Server Web client operations. Potential candidate workflows include ArcGIS Desktop, ArcGIS Engine, ArcGIS Explorer, and standard Web browser applications including ADF clients, JavaScript, Adobe Flash and Microsoft Silverlight rich internet clients.



ArcGIS Server Applications and Services. ArcGIS Server can provide Simple Object Access Protocol (SOAP)/XML-based data services (published reference images) and geoprocessing services to ArcGIS Desktop and ArcGIS Engine client applications, provide a 3D globe cached file data source for ArcGIS 3D Analyst and ArcGIS Explorer clients, and host a full range of map view and edit applications for Web HTML browser clients supported by out-of-the box .NET and Java Web map and editor server development kit components. ArcGIS 9.3 supports a REST and JavaScript API providing a variety of new Web client options, including KML services for use with Google and Microsoft geospatial client environments.

ArcIMS Web Mapping. ArcIMS was a popular solution initially deployed in 1997 for delivering dynamic maps and GIS data and services via the Web. For many years it provided a highly scalable framework for GIS Web publishing meeting the needs of corporate intranets and demands of worldwide Internet access. ArcIMS customers are rapidly moving to ArcGIS Server software to leverage the rich functionality available with the new ArcGIS Server software release. ArcGIS 9.3.1 provides a new optimized dynamic map service that outperforms equivalent map services deployed using the ArcIMS Image service. ArcGIS Server with cached map services provide high quality and high performance well beyond what was available with the legacy ArcIMS technology.

ArcGIS Image Extension. ArcGIS Image Extension changes how imagery is managed, processed, and distributed. The Image Extension provides fast access and visualization of large quantities of file-based imagery, processed on the fly and on demand. It provides rapid display of imagery for a number of users working simultaneously, without the need to preprocess the data and load it into a database management system (DBMS). ArcGIS Image Extension can be used as a data source for ArcGIS Desktop, ArcGIS Server, and ArcIMS Web mapping services. The ArcGIS Server image service extends Image Extension access to include the full range of Web Internet clients. Additional support is provided for AutoCAD and MicroStation CAD clients. On-the-fly processing can include image enhancement, orthorectification, pan sharpening, and complex image mosaicking.

Web Mapping Software Technology Patterns. ArcGIS Server provides a variety of Web mapping applications and map service deployment patterns. The CPT Calculator software technology selections include ArcGIS Server Map Viewer and Editor Application Development Framework (ADF) applications, SOAP services, REST services, and WMS services. Optimized map document (MSD) services are available with the ArcGIS 9.3.1. release. A variety of Software Performance Parameter selections are available for each technology pattern. Figure 2-17 provides an overview of the CPT Calculator ArcGIS Server software technology selections.



Standard ESRI Web Mapping Workflows. The most common ArcGIS Server workflow patterns are generated from the Calculator tab and listed in the Standard ESRI Workflow section of the CPT Workflow tab. The list includes the more common ArcGIS Server deployment scenarios. There are many deployment scenarios with significant variation in service time and traffic performance targets. Best practice is to use the CPT Calculator to complete a workflow analysis for each use case, and then use the Calculator generated workflow performance targets for your design. Figure 2-25 provides an overview of the pre-generated ArcGIS Server Standard ESRI Workflow selections.



Figure 2-26 provides a Workflow Performance Summary for the most common ArcGIS Server workflow profiles. This is a small sample of the many workflow combinations that can be generated from the CPT Calculator settings. A common WAN (1.5 Mbps) bandwidth connection is used to represent typical Web client display performance. Display traffic is the primary response time performance factor for most ArcGIS Server deployment profiles. Server processing times will impact system capacity and licensing, with less impact on user performance. The default workflows shown here use a 1024x768 map display resolution - display traffic and client response time improves significantly with smaller resolution image services (600x400 pixels is quite common for many Web services).



Developer GIS
EDN is an annual subscription-based program designed to provide developers with comprehensive tools that increase productivity and reduce the cost of GIS development. EDN provides a comprehensive library of developer software, a documentation library, and a collaborative online Web site that offers an easy way to share information. GIS Web Services: GIS Web services offer a cost-effective way to access up-to-date GIS content and capabilities on demand. With ArcGIS Web Services, data storage, maintenance, and updates are handled by ESRI, eliminating the need for users to purchase and maintain the data. Users can access data and GIS capabilities directly using ArcGIS Desktop or use ArcWeb Services to build unique Web-based applications. ArcGIS Online Services provide instant and reliable access to terabytes of data including street maps, live weather and traffic information, extensive demographic data, topographic maps, and high-resolution imagery from an extensive list of world-class data providers.



GIS Software Selection
Selecting the right software and the most effective deployment architecture is very important. ArcGIS technology provides many alternative architecture solutions and a wide variety of software, all designed to support specific user workflow needs. Figure 2-22 provides an overview of the GIS software technology alternatives. What is the best data source? What user workflows should be supported by GIS desktop applications? What can be supported by cost-effective Web services? What business functions would be best supported by network services? Where will mobile applications improve business operations? Understanding the available technology alternatives and how each will perform and scale within the available user environment can provide the information needed to make the right technology decisions.



GIS Data Source: Operations can be supported on local disk or CD-ROM, shared file servers, geodatabase servers, or Web data sources. Local data sources support high-performance productivity requirements with minimum network latency. Remote Web services allow connection to a variety of published data sources, with the drawback of potential bandwidth congestion and slow performance. There are other more loosely connected architecture solutions that reduce potential network performance latency and support distributed data integration.

Desktop Applications: The highest level of functionality and productivity is supported with the ArcGIS Desktop applications. Most professional GIS users and GIS power users will be more productive with the ArcGIS Desktop software. These applications can be supported on the user workstation or through terminal access to software executed on central Windows Terminal Server farms. Some of the more powerful ArcGIS Desktop software extensions perform best on the user workstation with a local data source, while most ArcGIS Desktop use workflows that can be supported more efficiently on a terminal server farm. Selecting the appropriate application deployment strategy can have a significant impact on user performance, administrative support, and infrastructure implementations.

Web Services: The ArcIMS and ArcGIS Server technologies provide efficient support for a wide variety of more focused GIS user workflows. Web services also provide a very efficient way to share data to support remote client workflows. ArcIMS provides the most efficient way to publish standard map information products. ArcGIS Server provides enhanced functionality to support more advanced user workflows and services. Web services are a cost-effective way to leverage GIS resources to support users throughout the organization and associated user communities.

Network Services: Intranet applications can access services provided by ArcGIS Server connecting directly through the server object manager. Network services can be used to support a variety of Web and network applications. Mobile Applications: A growing number of GIS operations are supported by more loosely connected mobile GIS solutions. ArcGIS technology supports continuous workflow operations that include disconnected editing and remote wireless operations. A disconnected architecture solution can significantly reduce infrastructure costs and improve user productivity for some operational workflows. Leveraging mobile services can provide alternative solutions to support a variety of user workflow environments.

Making the right technology choice can make or break your success. Technology is changing fast, and new innovations bring lots of promise. The temptation to select technology based on promise can contribute to a painful implementation and failed expectations. Selecting the right technology at the right time can lead to optimum success. Replacing aging technology is also important, missing the performance and productivity gains delivered with new technology innovation. Figure 2-28 shows a typical product life cycle, which is getting shorter as technology improves more rapidly each year.



The Capacity Planning Calculator provides a framework for modeling software performance and scalability on available hardware and network communication technology. The Calculator models what we understand about GIS technology patterns and key workflow performance parameters, relationships we can validate with well defined test benchmarks and operational experience. For single workflows, the Calculator provides a complete software and hardware solution. For Enterprise Design solutions, the Calculator provides workflow performance targets that can be used in the Enterprise Design. Figure 2-29 provides one more look at the CPT Calculator as we complete our software technology discussion.



Selecting the proper software and architecture deployment strategy can have a significant impact on user workflow performance, system administration, user support, and infrastructure requirements. The following Capacity Planning Demo provides an overview of the Calculator tab.

CPT Video: GIS Software Technology

The next chapter will discuss Software Performance, providing a much closer look at the software performance parameters and baseline performance models in the Capacity Planning Calculator.

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