Global Positioning System Reference
In-Depth Information
In contrast, the OGC proposals are not WS-I compliant. As for the use of
the SOAP Headers, Villa et al. (2008b) present some concrete examples of
how such headers can be effectively used. In fact, although their use in the
OGC integration proposals is not compulsory, the authors propose to use
them to manage, in a modular way, some common aspects of the INSPIRE
Web services, including for example the use of SOAP Headers for security
purposes. In fact, a header block could be used for carrying security-related
information to a specifi c recipient. Another way to take advantage of SOAP
Headers consists of using them for checksums and signature purposes: a
message producer could want to provide recipients with a message along
with a means to determine whether a message was altered during its path.
Moreover, a Header block could carry information useful to a receiver to
check the integrity of the binary data attached to the SOAP message.
A SOAP Header could also be used to provide for human readable
information without interfering with the content of the Body of the SOAP
message. Finally, a SOAP Header could be used to transport all metadata
or information not strictly connected with the message encoded in the Body
element. INSPIRE suggests this solution also to solve the multilingualism
issue.
SOAP performances
As previously discussed, the advent of the SOC paradigm has revolutionized
the way distributed applications are designed and implemented. Among the
various standards upon which such solutions are based, SOAP represents
one of the cornerstones for the achievement of interoperability among
heterogeneous systems. However, the massive adoption of SOAP has
stimulated a debate around a fundamental aspect, namely its performance
during the implementation of complex and large scale distributed
applications.
A quite complete description of the SOAP performance issues and a
review of the research efforts aimed at SOAP performance enhancement
can be found in Tekli et al. (2012). For the purposes of this section, the
main performance issues are mentioned that could occur when SOAP is
used to transfer large amounts of data, such as in distributed geographic
environments. According to Tekli et al. (2012), the performance metrics of
service-oriented environments can be grouped into three main categories:
the response time, the throughput and the network traffi c. The response
time (latency time) can be seen as the time perceived by a client to get a
response; the throughput can be seen as the number of requests fulfi lled in
unit of time, and the network traffi c is the total size of messages exchanged
during the whole communication. By taking these metrics into account, the
use of SOAP exhibits several problems mainly due to the XML message
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