Toshiro Takase

Optimizing Web services performance by differential deserialization

Web services technology has emerged as a key infrastructure that enables business entities to interact with each other without any human inventions. In order for the technology to be widely used, especially in any field where a large volume of transactions may be processed, it is highly desirable that the Web services engine should tolerate such environments. In this paper, we present a novel approach for improving Web services performance. We first focus on the fundamental characteristics of the Web services in that the SOAP messages on the wire are mostly generated by machines and have a lot of similarities among the processed messages. By making use of these features and eliminating the redundant processing, we propose a new deserialization mechanism that reuses matching regions from the previously deserialized application objects from earlier messages, and only performs deserialization for a new region that would not be processed before. Through our experiments in this paper, we observed that our approach obtained a 288% performance gain (maximum) by incorporating the differential deserialization into the Axis SOAP engine.

An adaptive, fast, and safe XML parser based on byte sequences memorization

XML (Extensible Markup Language) processing can incur significant runtime overhead in XML-based infrastructural middleware such as Web service application servers. This paper proposes a novel mechanism for efficiently processing similar XML documents. Given a new XML document as a byte sequence, the XML parser proposed in this paper normally avoids syntactic analysis but simply matches the document with previously processed ones, reusing those results. Our parser is adaptive since it partially parses and then remembers XML document fragments that it has not met before. Moreover, it processes safely since its partial parsing correctly checks the well-formedness of documents. Our implementation of the proposed parser complies with the JSR 63 standard of the Java API for XML Processing (JAXP) 1.1 specification. We evaluated Deltarser performance with messages using Google Web services. Comparing to Piccolo (and Apache Xerces), it effectively parses 35% (106%) faster in a server-side use-case scenario, and 73% (126%) faster in a client-side use-case scenario.

Efficient Web services response caching by selecting optimal data representation

We discuss the design for an efficient response cache mechanism appropriate for the Web services architecture. The important feature of Web services is its interoperability between heterogeneous platforms. This interoperability is based on widely accepted standards such as XML, SOAP, and WSDL. We describe a response cache mechanism for Web services client middleware without any extensions to these standards so that the client can participate transparently in the existing Web services community. We propose three optimization methods to improve the performance of our response cache. The first optimization is caching the post-parsing representation instead of the XML message itself. The second is caching application objects. For this optimization, we show some copying processes that are dependent on the type of cached objects. The third optimization is for read-only objects. These methods reduce the overhead of XML processing or object copying. We have implemented a prototype of a response cache on Apache-Axis, and evaluated these optimization methods through experiments for Google Web services. Finally, based on the experimental results, we discuss the optimal configuration of these methods based on data types.

XML digital signature system independent of existing applications

This paper describes a turnkey solution to add a XML digital signature capability without modifying existing XML-based B2B systems. The signature proxy between applications watches for XML messages exchanged on the network. Outbound messages are received by the proxy and automatically signed and by a signature server implemented as a Web service. Inbound messages are also verified by using the proxy and the signature server The existing applications do not care about handling of digital signatures. The signature server can also provide (1) content-based key selection and (2) logging of signed documents with fine-grain access control. The system introduced in this paper is called the XML Security Services Suite (XS-Cube), a set of security-related Web services including digital signatures.

Separating Oblivious and Non-oblivious BPs

This paper gives an exponential separation on the depth of branching programs (BPs) between oblivious and non-oblivious BPs. Namely, there is a difference just like the difference between sequential and NC computation: (i) There is a Boolean function f1 of N variables which can be computed by a polynomial-size, syntactic BP with a depth of 2 log N - log log N + 1 but cannot be computed by any oblivious BPs with a depth of (2-Ɛ) N for some Ɛ ∈ o(1). (ii) Similarly, there is an f2 computed by a syntactic depth of log3 N but not by an oblivious depth of Ω(N log N). (iii) We also show that any (unrestricted) BP of depth t can be simulated by an oblivious BP with a depth of N + «(t - log N)/(log log N + C»ċN. The third result implies that f1 cannot be computed by any BP with a depth less than log N +log log N and f2 not with a depth of o(log N ċ log log N). Note that most bounds in this paper include constant factors and lower-degree terms.