Global Positioning System Reference
In-Depth Information
The GeoServices REST API is stateless and each request contains
all the information necessary for a successful processing. The standard
representation for resources is JSON (although, developers may support
resource representations in other different data formats) but in order to be
compatible with the majority of existing platforms, the API supports only the
GET and POST methods. A hierarchy of endpoints (URL) provides access to
all resources and operations exposed by the GeoService. Some resources, in
particular, are “controller” resources and can be used to perform operations,
such as querying and editing information stored on the server.
Conclusions
The SOC paradigm represents a radical change in the way distributed
applications are designed and implemented. By overcoming diffi culties
exhibited by previous middleware technologies, such as CORBA, this
approach has promoted the development of loosely coupled solutions
capable to guarantee the sharing and reusing of functionality. The
cornerstone behind the new computing platform is the idea of service, an
independent software module that performs certain operations. Among the
various software proposals matching the general defi nition of service, in
this chapter the proposals from W3C and OGC are discussed, whose success
has been determined by both the simplicity of access and the ubiquity of the
components, and the common goal of standardization and interoperability.
However, as shown throughout the chapter, despite sharing the same
objectives, these services are based on different standards, namely W3C
services are based mainly on the SOAP and WSDL standards, while the OGC
services specifi cations are based on standards developed independently
from SOAP or WSDL. In particular, each OGC service represents a separate
standard designed to handle a specifi c kind of data.
These differences must be carefully kept into account when dealing with
service composition, an important feature of a services platform. Services
composition is without doubt one of the hallmarks of this new computing
paradigm. In fact, service-based applications can satisfy client requests by
dynamically binding two or more services in a manner totally transparent to
the fi nal user. Among the proposed approaches for the services composition,
services orchestration is one of the most commonly used. However,
because of their different standards, a seamless orchestration of W3C and
OGC services is still a complex and challenging task. As described in this
chapter, the current solutions that try to realize such integration classify
the problems that need to be addressed into three main categories: Data
Handling, Functionalities Mapping and Metadata Management. Such a
subdivision is, in our opinion, a valid starting point for the identifi cation of
future research directions. In particular, for the Metadata Management, the
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