Database Reference
In-Depth Information
Amazon Web
Services
Google App
Engine
Windows Azure
WSDL
WSDL
WSDL
HTTP
SOAP/REST
Interface design
SOAP/REST
public Result InstantResponse(String value) {
// Echo the receiving value back to client
// Test net response time
}
public Result Read(String value) {
// Retrieve data from DB based on the given value
// Test DB read performance
WSDL
}
public Result Create(String content) {
// Persist given content into DB
// Test DB write performance
Client Testing Application
}
...
Fig. 4.3
Contract-First Web Service based client application
The evaluation interface hides variations on the cloud side. In practice, the
underline design of the three cloud platforms are different from each other. The
Contract-First Web Services hide heterogeneous implementation of each cloud
platform: Tomcat 6.0, Apache CXF, and a local PostgreSQL database are used
on a small Ubuntu-based instance in Amazon EC2; Windows Communication
Foundation (WCF) and C# codes are used on Microsoft Windows Azure; while
Python-based ZSI and Zope Interface frameworks are used in Google App Engine.
However, it is noted that potential performance difference is inevitable due to differ-
ent programming languages. Thus, the CARE framework cloud server components
follow the design principle of always using the native/primary supported language
of the cloud platform in order to build the most optimal and efficient test components
for each cloud platform.
4.3
Experiment Results and Exception Analysis
In this section, quantitative results of four test set methods will be examined.
Moreover, exceptions and errors captured during the evaluation will be analyzed
by considering the results as an average over all test results. Some environmental
information for the conducted tests are noted here:
The client environment executing the CARE evaluation strategy runs on 3 Debian
machines with Linux kernel 2.6.21.6-ati. Each evaluation machine is a standard
