International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
The open source JBoss jBPM engine was selected as the work
flow engine for the NWG architecture. jBPM is an extensible and
flexible process engine that can run as a standalone server or
embedded in any Java application. JBoss jBPM delivers the
capability of developing new automated business processes and
work flows with industry-standard orchestration using Business
Process Model and Notation (BPMN V2.0). BPMN is a standard
specification created by the Object Management Group (OMG)
that defines a standard language to model business process
including execution semantics that can be understood by both
business analysts and technical people. The usage of jBPM has
been instrumental in modelling our work flow from the start to
finish including human steps and providing e-mail alerts for the
different wait state in-between process.
Job Scheduling
There are a lot of job schedulers out there that have different
capabilities. We selected Quartz the enterprise Job scheduler to be
our scheduler of choice since it provides avery extensive sets of
functionality and is a mature platform to build our applications on.
Having a robust job scheduler integrated in the architecture has
allowed us to run multiple jobs from harvesting daily flight logs to
sending nightly what remains to fly reports efficiently in very
customizable schedule.
Monitoring Services
The deployment stack consists of tools that provide a reliable
means of detecting and monitoring faults in the production
servers. Even though most production servers have redundancy,
automating the response and alerting the operation group
whenever there are interruptions in service and/or a resource
reaches a critical state is a very important part of providing a
reliable system. For these reasons we have developed monitoring
tools based on open source that are able to diagnose problems and
provide a self-healing environment if possible. For example, some
of the capabilities of the alert and monitoring system are watch
dogs for WMS servers using the GetCapabilities and GetMap
responses.
High Performance Computing
The Condor® Project is our selected high performance computing
platform to perform computationally intensive jobs on a grid of
dedicated clusters. A module to interact with the Condor cluster
for submission and monitoring of jobs within the application
server was developed. This module allows us to increase the
turnaround time of the business process and maximize the usage
of the HPC cluster resource since the system is now able to submit
jobs to the cluster as soon as the precondition for that step in the
work flow engine are finished by either humans operators or
another application.
Web Services
Standards enable systems to be built that easily discover and
seamlessly combine spatial information from different sources and
share it among many users and applications (Beshah et al., 2008).
At NWG we have built an Enterprise Spatial Platform that is
designed to securely manage and deliver geospatial data to users
operating on rich client desktop systems and web clients. We
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expose the different processed geospatial data and their status
throughout the workflow using a number of OGC web services,
Currently the system supports the OGC Web Mapping Service
(WMS), Web Feature Service (WFS) and Web Coverage
Service(WCS).
In addition, other core open source technologies like PostGIS,
Hibernate, OpenLayers, GWT, GeoTools and others were
integrated at different layers of the architecture. The selection and
integration of these different frameworks and libraries to create a
single coherent geospatial platform that is firmly based on both
enterprise and high performance computing was the biggest
challenge we faced.
REAL WORLD USAGE
NWG deployed the first version of the enterprise mapping system,
coined Production Tracker, in 2010 and has since ingested every
flight into the system as illustrated in Figure 3.
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Figure 3: Overview of acquisition blocks in Production Tracker
Since the initial deployment the Production Tracker has been
constantly updated and as of April 2012 the latest version exposes
functionality that fulfils the requirements from Planning through
Ingest and initial QC.
Once the flight crew has recorded imagery an email with an
attached flight execution export that contains planned and
recorded flight lines is sent to the office where by it is
automatically ingested into the Production Tracker. The office can
immediately check line coverage and consistency without having
access to the full dataset. An example is given in Figures 4 & 5.
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