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[ArcView IMS] [MapObjects
IMS] [ArcIMS]
[MapGuide]
[MapServer]
[OpenGIS
Multiviewer] [Gis
Viewer]
ArcView
IMS (ESRI)
 ArcView
IMS is an extension of ESRI's GIS application, ArcView 3.x,
and one of the first available Map Server systems. It requires
an open session of ArcView running on the Web server or on
a machine with direct communication with IMS AV middleware
(esrimap.dll), installed in the Web server. This middleware
processes the requests of the client and passes them to the
ArcView IMS session. The map services are easy to put online,
preparing views with different map compositions and classifications.
The compositions are fixed and the client cannot change them
dynamically. Once the map is defined with the different themes,
it is served directly on Internet, outside the ArcView application
that is running. All the client's requests to open, zoom,
or pan interact with the ArcView session and the views of
the session react to these demands.
MapObjects
Internet Map Server (ESRI)
 MapObjects
Internet MapServer (MOIMS) is both a complete application
for publishing maps on the Internet and a programming platform.
It can be used to publish maps designed in ArcExplorer 2.x.,
without need of programming. Likewise, MOIMS permits the planning
of GIS applications online, using the functions and objects
available in MOIMS, and together with the MapObjects library
programming (based on COM).
Publishing
maps with ArcExplorer-Web (AEWeb)
AEWeb,
available as client HTML or control Active X, and based on
the free and freely distributed program, ArcExplorer 2.x,
is an explorer of geographical data that permits navigating
and consulting data offered by the MOIMS system servers. Besides
the geographical viewing of data, it offers the data discharge
option in vector format (shape) to carry out local types of
operation, with ArcExplorer 2. x or with any another GIS tool
that supports the shape format, such as the analysis programs
ArcView or ArcInfo.
MOIMS
has an assistant for easy publishing of map services on the
Internet. These services are designed beforehand with the
application and are stored as *.aep files.
Programming
GIS applications
To
create your own GIS applications on Internet, you need a programming
system such as Visual Basic, Visual C + +, or Delphi. Integrating
the functions included in the programming library (COM) MapObjects,
you can create GIS applications adapted to the user's needs,
including advanced functions of spatial analysis, such as
geoprocessing of several layers of information (e.g., cutting,
overlaying).
Because
of the programming needs that both the Client and Server applications
require, with their respective functions, the investment of
time for developing a map server system on Internet with MOIMS
is very high. For this reason, the only limitations for the
functionality of the application of this system are the programmer's
capacity and the time or budget available.
Client
applications can be developed in HTML (JavaScript), or, for
clients with more advanced functionality, in Java (or ActiveX)
in "Applets" form.
To validate this system of map services on Internet, the GIS
Laboratory has developed a demonstration of a client/server
system that can freely access any of the available data in
a server and add them to its display of maps.
For
this, the basic functionalities of map display, change of
symbol, and the function for adding layers of information
stored in the server have been implemented. Each time that
the user adds a layer of information originating in the server,
the client dynamically adjusts the new display.
The
system was planned using Visual Basic (with the MOIMS and
MapObjects Professional libraries) for the server application,
and Java SDK 1.2 for the design of the client and its display
capacities.
Examples:
Arc
Internet Map Server - ArcIMS (ESRI)
 A
key characteristic of the new ESRI system for publishing maps
on Internet, ArcIMS 3.x, is its capacity to establish a common
platform for the exchange of GIS data and services on the
Web (ArcIMS is also compatible with the map services protocol
of the GIS Consortium - Open GIS Consortium [OGC]). The ArcIMS
technology is based on the "multi-tier" (multi-level)
architecture, widely distributed and scalable, and its system
is composed of clients, services, and database, in a structure
of three "tiers".
The
components of the ArcIMS server include:
Spatial
Server: Creates digital images of vector and raster data.
It gives access to geographical elements and processes consultations
in the database.
Applications Server: Handles the balance of the processes
and incoming demands, and maintains a registration of the
map services executed in the spatial servers.
Connectors to the Applications Server: Connects the
Web server to the Applications server. ArcIMS provides three
types of connectors - Servlet (Java), ColdFusion, and ActiveX
(VB, ASP). "Servlet" is the standard connector (Java
application in the Server) and uses ArcXML (internal language
of ArcIMS, based on XML) to communicate the Web server with
the Applications server. The connectors ActiveX and ColdFusion
work with their own clients and translate their internal language
to ArcXML.
Administrator: Group of assistants of easy use for
the management of all the functions and tasks related to the
server. Assistants exist to create and manage map services,
to design the maps to publish, to create the Web sites that
provide user access, and to administer the spatial servers.
ArcXML:
Communication
among the different components of ArcIMS is carried out through
the ArcXML protocol. It is a derivation of XML (extended HTML),
and is different from this in that ArcXML does not describe
the structure or appearance of a Web page, but the structure
of the following content and functionality:
- Configuration
of map services: Define the content and design of maps to
disseminate, including the spatial layers of information
and their symbology.
- Consultations:
Employ a filter to existing map services and specify the
part of the map and related data that are to be processed.
- Answers:
Send the information required to the client. ArcXML is based
on technology XML, the new standard in information exchange
and management, key for spatial databases distributed by
Internet.
Design
of map service:
The
tool for designing map services guides the user in creating
Web pages and clients. For developing the basic map services
you do not need to program or edit HTML code. The assistant
functions with friendly dialogues and creates the necessary
files at the end of each session. ArcIMS includes two types
of clients, an HTML visualizer and a Java visualizer, which
differ in their graphic appearance and functionalities. The
Java client offers more functions (identical to those of ArcExplorer
3.x), but needs a download of 3.5 MB at the user's computer.
ArcIMS
offers two types of maps services:
The
image server generates and transmits the maps in JPEG, PNG,
or GIF format to the clients. The map images can be created
from shapefiles, ArcSDE data, and different types of raster
data. The server of geographical elements (feature server)
transmits (only) to the Java client shapefiles and ArcSDE
layers in compressed format. At the same time, the client
receives instructions suitable for processing the transmitted
data. This type of map service permits a more advanced functionality:
- Labels
geographical elements in the client.
- Changes
map symbology.
- Spatial
selection in the client.
- Overlaying
of geographical elements originating in various map servers
or from the local system.
Examples:
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