Using XML-Based Multicasting to Improve Web Service Scalability

Abstract

Web services’ (WS) emphasis on open standards provides substantial benefits over previous application integration techniques. A major WS feature is SOAP, a simple, robust and extensible XML-based protocol for the exchange of messages. For this reason, SOAP WS on virtual hosts are now widely used to provide shared functionalities on clouds. Unfortunately, SOAP has two major performance-related drawbacks: i) verbosity, related to XML, that leads to increased network traffic, and ii) high computational burden of XML parsing and processing, that leads to high latency. In this paper, we address these two issues and present new results regarding our framework for Differential SOAP Multicasting (DSM). The main idea behind our framework is identifying the common pattern and differences between SOAP messages, modeled as trees, so as to multicast similar messages together. Our method is based on the well known concept of Tree Edit Distance, built upon a novel filter-differencing architecture to reduce message aggregation time, identifying only those messages which are relevant (i.e., similar enough) for similarity evaluation. In this paper we focus on recent improvements to the filter-differencing architecture, including a dedicated differencing output format designed to carry the minimum amount of diff information, in the multicast message, so as to minimize the multicast message size, and therefore reduce the network traffic. Simulation experiments highlight the relevance of our method in comparison with traditional and dedicated multicasting techniques.

Building semantic trees from XML documents

“…The same applies for services discovery, recommendation, and composition: searching and mapping together semantically similar WSDL/SOAP descriptions when processing WS, and performing semantic-aware mapping of XHTML/keyword descriptions when dealing with RESTful and/or mobile services [56,115]. XML similarity and differential encoding can also be utilized to reduce processing costs and improve the performance of SOAP communications [104]: comparing new SOAP messages with message patterns or WSDL grammars (at the message sender/receiver side), processing and transmitting only those parts of the messages which are different (cf. review in) [105].…”

Approximate XML structure validation based on document–grammar tree similarity

“…-Quantifying the similarity and identifying the relations (i.e., inclusion, intersection, disjointness, and equality) among XML element content values, particularly among RSS items [60], developed toward RSS merging [59]. -Developing a filter-differencing framework for SOAP multicasting, identifying the common pattern and differences between SOAP messages, modeled as XML trees, to multicast similar messages together [71,72].…”

“…Evaluating the similarity between heterogeneous documents and grammars can be exploited in various application scenarios requiring accurate and ranked detection of XML structural similarities [10,62], ranging over: XML document classification against a set of grammars declared in an XML database [10,80], (just as DB schemas are necessary in traditional DBMS for the provision of efficient storage, retrieval and indexing facilities, the same is true for DTDs and/or XSDs in XML repositories), XML ranked document retrieval via structural queries [32,55] (a structural query being represented as a DTD/XSD in which additional constraints on content can be defined), the selective dissemination of XML documents [10] (user profiles being expressed as DTDs/XSDs against which the incoming XML data stream is matched), as well as Web service matching and SOAP processing (searching and ranking services which best match WSDL 1 service requests, and comparing outgoing SOAP messages to sender-side WSDLs, processing only those parts of the messages which differ from the WSDL descriptions in order to avoid unnecessary overhead, and thus reduce processing cost in SOAP parsing [74], serialization [2], and communications [72,78]). In this study, we focus on the problem of evaluating the structural similarity between an XML document and an XML grammar, i.e., comparing the structural arrangement and ordering of XML elements/attributes in the XML document and the XML grammar.…”