Global Positioning System Reference
In-Depth Information
Typically, the motivation for using cloud computing includes:
Scalability:
it enables smooth scaling in many dimensions;
High Availability:
it provides highly available services;
Flexibility and reliability:
it supports redundant, self-recovering (fault-
tolerant) programming models that allow services to recover from
many unavoidable hardware/software failures;
Un-predictable resource usage support:
it supports application whose
resource usage cannot be fully determined a-priori;
Transparency:
it virtualizes data processing and workfl ow execution;
Thin client support:
all forms of processing and data storage are done
in the cloud, therefore, it offers support for any kind of client, more
especially, thin client;
Service orientation:
everything in the cloud is offered as a service;
therefore, there is possibility of composing more complex services
from already existing services;
Cost efficiency:
it offers low cost of entry and high return on
investment.
Cloud geoprocessing applications are getting more complex, compute-
intensive, and data-intensive. Furthermore, the growth of the web and
sensor-based devices has resulted in an increase in the number of users
of these applications, their requirement with respect to functionality and
Service Level Agreement (SLA), and the sizes and distribution of the data
processed. However, the infi nite scale of computing resources is idealized
a potential solution.
At the moment, several research efforts have gone into running
geospatial applications within the cloud. The remaining part of this section
discuss the approaches used with the context of the NIST classifi cation of
cloud computing service models which includes Software as a Service (SaaS),
Platform as a Service (PaaS), and Infrastructure as a Service (IaaS).
Software as a Service (SaaS)
In this cloud model, application software (together with any other needed
software, operating system and hardware) is provided to the user, typically
through the some thin client interface (web browser or some other service
oriented interfaces). Common examples of these services include Google
Apps, Web-based email services, Microsoft Live Mesh, Google Earth, Map,
Gmail, and Docs, OGC Web services. The mechanisms ensuring availability
and scalability of this service can vary widely. For instance, some services
can be scaled directly as below:
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