Ahmet Sayar » web services

Information Services for Grid/Web Service Oriented Architecture (SOA) Based Geospatial Applications

ahmet — Sun, 08 May 2011 21:31:28 +0000

Geographical Information Systems (GIS) presents data-intensive environment for
acquiring, processing and sharing geo-data among interested parties. In order to serve
geographical information to users in such environment, Service Oriented Architecture
(SOA) principles have gained great importance. In SOA-based systems, Information
Services support the discovery and handling of these geospatial services.
Some options for Information Services in SOA-based GIS systems include a) the Open
GIS Consortium (OGC) Web Registry Service (WRS) and b) the Universal Description,
Discovery, and Integration (UDDI). WRS is an OGC standard to discover/publish service
information of geospatial services. It presents a domain-specific registry capability for
geospatial information. UDDI is domain-independent standardized method for
publishing/discovering information about Web Services. As it is WS-Interoperability
(WS-I) compatible, UDDI has the advantage being interoperable with most existing
Grid/Web Service standards.
This study presents an approach combining domain-specific registry capabilities of WRS
and WS-I compatible UDDI Specifications. We extend UDDI Information Model to
support geospatial services. Our approach supports not only quasi-static, stateless
metadata, but also more extensive metadata requirements of rich interacting systems. The
implementation of our approach is being used to support a GIS workflow system which is
a part of NASA Solid Earth Virtual Observatory (SERVO) Grid project.

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OGC Compatible Geographical Information Systems Web Services

ahmet — Sun, 08 May 2011 21:26:49 +0000

The Open Geospatial Consortium (OGC) defines a number of standards, both for data models
and for online services, that has been widely adopted in the Geographical Information System
(GIS) community. This has lead to a number of software development efforts, online data
archives, and application communities. We survey these in the first part of this report. We
furthermore find that the OGC standards are very compatible with Web Services standards,
although they are not technically implemented this way. We therefore, in the second part of
this report, describe our group’s efforts to reimplement OGC standard services as web
services. We focus particularly on the Web Map Service.
We also have built bridging services that allow our Web Service compatible WMS to interact
with non-Web Service versions of WMS. Cascading WMS is the key point in our proposed
solution for the interoperability problems in the GIS WMS services. Since Web Service
oriented WMS has different request response paradigm from non-Web Service versions, we
have extended cascading WMS by adding request handler functionality. This kind of WMS
behaves like both a cascading WMS and a proxy to handle different types of requests to
overcome interoperability problems between different WMS systems.

Implementing GIS Grid Services for the International Solid Earth Research Virtual Observatory

ahmet — Sun, 08 May 2011 21:23:59 +0000

We describe our continuing work on implementing Open GIS Consortium (OGC) compatible Grid
Services for the International Solid Earth Research Virtual Observatory. Our initial efforts focused
on collecting Earthquake and GPS data from various sources, converting them to GML and
enabling query capabilities using pure Web Services approach. We have extended this work by
creating Web Services implementations of OGC-Web Feature Service and OGC-Web Map Service
for serving GML-formatted data. We also describe a Fault Tolerant High Performance Information
System (FTHPIS) to tie these services together.

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Implementing Geographical Information System Grid Services to Support Computational Geophysics in a Service-Oriented Environment

ahmet — Sun, 08 May 2011 21:21:23 +0000

We describe the architecture and implementation of the Solid Earth Research Virtual Observatory (SERVO)’s Complexity Computational Environment. We base our design on a globally scalable
distributed “cyber-infrastructure,” or Grid, built around a Web Services-based approach consistent with the extended Web Service Interoperability (WS-I+) model. In order to investigate problems in earthquake modeling and forecasting, we need to programmatically couple numerical simulation codes and data assimilation and mining tools to online observational data sets, including GPS stations, fault data, and seismic activity catalogs. These observational data sets are now available on-line in internet-accessible forms, and the quantity of this data is expected to grow explosively over the next decade. As part of our efforts in building SERVO, we are extending these online data repository capabilities so that they are not just available directly for human users, but may also
be searched, filtered, and streamed to simulation codes that are also managed by SERVO services.

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Message Exchange For Web Services-Based Mapping Services

ahmet — Sun, 08 May 2011 21:17:39 +0000

The Open Geospatial Consortium (OGC) [1] defines a number of standards, both for data models and for online services, that has been widely adopted in the Geographical Information System (GIS) community. This has lead to a number of software development efforts, online data archives, and application communities. The emergence of Web Service technique overcomes the shortcoming of
traditional Distributed Object technique and provides the interoperable capability of cross-platform and cross-language in distributed net environment. GIS services will be implemented more extensively by using Web Service approach. A spatial data infrastructure lets many GIS vendors share data stores and applications in a distributed environment. GIS basically involves the integration of data and services from multiple sources from different vendors. The Web services architecture establishes a standard interconnection rules between services and information clients that nicely support the dynamic integration of data, which is the key to creating a spatial data infrastructure. By introducing Web Services, distributed GIS services from different vendors can be dynamically integrated into the GIS applications using the interoperable standard communication protocols of the Web Services. To be able to benefit from the Web Services in the GIS applications, all the service providers should provide their services as Web Services. General acceptance from the vendors increases the interoperability and enhances the GIS applications. We find that the OGC
standards are very compatible with Web Services standards, although they are not technically implemented this way. To be able to benefit from Web Services technologies we have built a common architecture to convert any OGC GIS services to Web Services and applied this to our current WMS project.

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Development of Java Web Services with Eclipse

ahmet — Sat, 16 May 2009 10:01:49 +0000

Web Service applications require a couple of libraries such as axis, servlet-container and java software development kits. If you want to build a Web Service application on the Eclipse IDE, you have to be careful. Below you will see the basic steps when you go through any tutorial you find on the web.

Before starting, please download/install the below list.
Please do NOT use any other versions of these software/library packages. In other case you will encounter many debugging problems that you can not cope with in eclipse.

0.
Get the below packages with the right versions

axis2-1.2
Dynamic web module 2.4 (you dont need to download it is already in eclipse)
apacxhe tomcat 5.5
java 5
1. Setting axis2 runtime env
Window-preferences-WebServices-Axis2 Preferences
C:Program Filesaxis2-1.5 and ok

2.
Next we need to create a project with the support of Axis2 features. Open File -> New -> Other… -> Web -> Dynamic Web Project

Give the project a name
set the target runtime Apache Tomcat v5.5
Dynamic Web Module version 2.4
Add java 1.4 and set

3.
Right click on the project name and select Project facets
click “Axis2 Web Services”

4.
Select Converter.java, open File -> New -> Other… -> Web Services -> Web Service
-chose web service runtime first
Apache Axis2

5.
TEST:
http://localhost:8080/Axis2WSTest/