Abstract:
The growing synergy between Web Services and Grid or cloud based technologies is enabling profound, dynamic interactions between applications dispersed in geographic, institutional, and conceptual space. Such deep interoperability requires the simplicity, robustness, and extensibility for which XML has been conceived, making it a natural lingua franca for the network. Along with these advantages, there is a degree of inefficiency that may limit the applicability of XML.
In this paper, we investigate the limitations of XML for high-performance and high-interactive distributed computing. Our experimental results clearly show that focusing on parsers, that are routinely used for desterilize XML messages exchanged in these system, we can improve the performance of a generic the end to end web services based solution. Then we present a new parser, the Cache Parser, which uses a cache to reduce the parsing time by reusing information related to previously parsed documents/messages similar to the one under examination. Finally, we will show how our fast parser can improve the global throughput of any application based on Web or Grid or Cloud Services, or also RPC calls in general.

Key words: Web Service, Cloud Services, 3 tier architecture, SOA, RPC, Service Oriented Architecture

The may Web Services fully solve the “global enterprise integration” problem, but the proposed solution seems to exhibit a poor performance, and we believe that this could pose serious limitations on their actual applicability, as the number of commercial users will increase.
As shown in paragraph 2 we also believe that one of the limitations in using a full WS approach for implementing complex and highly interactive systems, comes from the large de-marshalling costs incurred on the receiver sides.
To solve this problem, we have designed a new parser: the Cache Parser. It is able to “well and quickly” retrieve information from XML documents, using previous knowledge about the document syntactic tree. In particular, our Cache Parser, which is used to de-marshal XML messages on the receiver side:

• Uses a checksum to detect if a new document is “well formatted”, and to know if it shares the syntactic tree with an already parsed one.
• Takes advantage of this XML-Document syntactic tree stored in a cache.
• It is based on a strict collaboration between sender and receiver.
• Consistently reduces the receiver parse time, without increasing the sender document creation time.

This algorithm is 25 time faster than a pull parser and if used in a WS scenario it can allow a 1.54 performance improvement factor in term of request handled per second. Finally it can be applied in any scenario where the client and the server decide to cooperate.

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Improving the #performance of XML based technologies by caching and reusing #Information. #Webseries #RealTime #CloudComputing #API #APIs #programming #softwareengineering
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F. Lelli, G. Maron, and S. Orlando. Improving the Performance of XML Based Technologies by Caching and Reusing Information.. IEEE International Conference on Web Services (ICWS), Chicago, September 2006.

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Is it possible to achieve a Client Side Estimation of a Remote Service Execution?

Abstract:
Many use cases, concerning the monitoring and controlling of real physical instruments, demand deep interaction between users and services that virtualize the access to such instruments/devices. In addition, in order to realize high interoperable solutions, SOA-based Web/Grid Service technologies must be adopted. When the access to one of these services is performed via internet using a Web Service call, the remote invocation time becomes critical in order to understand if an instrument can be controlled properly, or the delays introduced by the wire and the serialization/ deserialization process are unacceptable. This paper thus presents methodologies and algorithms, based on a 2k factorial analysis
and a Gaussian Majorization of previous service execution times, which enables the estimation of a generic remote method execution time. Furthermore it suggests three different software architectures, where the developed algorithms and methodology could be integrated in order to automatically profile the end-to-end service. It is worth noting that our proposals are validated using suitable benchmarks and extensive tests coming out from a real (not simulated) environment. In addition, the outcome of this paper have been used in the realization of a service for remote control, monitor, and manage of a pool of instruments/devices.

Key words: Web Service, Quality of Service, QoS, Grid, Cloud Services, Response Time

In this paper you will understand the state of the art on Quality of Service in today digital services with particular attention to Web Services. In this scenario, we proposes a set of solutions that enable a remote service invocation time to be predicted in a general scenario. The contribution of this paper can be divided in three different parts:

• Section 3 formalizes the problem while Sections 5 and 5.1 validate this formalization by providing a dataset for web service QoS study. In particular, the dataset consists of 2304000 samples (of 9 significant values each) organized in 2304 different tests.
• In the second part of this paper (Section 4, 6, and 7) we analyze the collected dataset in a more exhaustive way. Two variants of a methodology that utilizes a Gaussian approximation of the dataset distributions, in combination with a regression model of the key factors that influence the average and the standard deviation, have been developed in Section 4.
• Then, in Section 6 our estimators are validated with experimental results in several scenarios. In the last part of this paper (Section 7), we propose three different software architectures that can utilize the developed methodologies and algorithms. It is worth noting that the presented solutions have been already adopted in a Grid context during the design and implementation of our IE

We have also experienced that in case of server overload, the number of deadline misses increases. This suggests a possible approach for an automatic organization of the clients that balances the servers’ load, and that could be exploited to solve the use cases mentioned in the introduction of this paper. If the number of deadline misses is greater than the expected
ones, the server machine is probably overloaded. So clients could/should decide to use a different machine, in which an identical copy of the invoked service is deployed.

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Client Side Estimation of a Remote Service Execution. #Webseries #RealTime (sort of) #CloudComputing #API #APIs #programming #SoftwareEngineering
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F. Lelli, G. Maron and S. Orlando. Client Side Estimation of a Remote Service Execution, 15th Annual Meeting of the IEEE International Symposium on Modelling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS), Istanbul, Turkey October 2007

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Current cloud service description languages envision the ability to automatically combine cloud service offerings across multiple abstraction layers, i.e. software, platform, and infrastructure service offerings, to achieve a common shared business goal. However, only little effort has
been spent in this direction. This paper formalizes the issue of automatic combination of cloud services showing its computationally intensive nature. In order to overcome this issue we propose a Resource Description Framework (RDF)- based prototype implementation that leverages a batch process for automatically constructing possible combinations of cloud services. Using this approach we are able to analyze possible combinations of cloud services that may fit particular customer needs in a timely fashion

Some relevant Key words: Cloud, Cloud Services, Service, Composition, RDF for Cloud

Cloud resources offered as services can be described using a common schema model and hence can be composed in order to achieve a common business goal. We present in this paper the issue of composing cross-layered cloud services to build a Service-based Cloud Application (SBCA), and formalize it as a tree navigation algorithm involving external approaches for matching cloud service descriptions.
Given the fact that there could be a huge number of cloud service offerings in a real marketplace, this algorithm may grow exponentially and become a computationally intensive task. For our prototype implementation, RDF is used to create a sample model containing sample cloud service offerings, a batch process is implemented to continuously scan the model and discover possible compositions of cloud services, and SPARQL is used to retrieve cloud services and their possible compositions in a timely fashion. In the future, we intend to continue investigating the issue of cross-layered cloud service composition in order to discover and quantify the benefits and the limits of this approach by providing experimental results.

Full article available at the following link:

Issue in Automatic Combination of Cloud Services:
https://doi.org/10.1109/ISPA.2012.71

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D. K. Nguyen and F. Lelli, Issue in Automatic Combination of SaaS, PaaS and IaaS, 10th International Symposium on Parallel and Distributed Processing with Application ISPA 2012 track Clouds for Business and Business for Clouds, Spain, Madrid, July 2012

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• The Many Faces of the Integration of Instruments and the Grid

#issues in #automatic Combination of #Cloud #services for #CloudComputing #RDF and understanding meta-information
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