Runtime Enforcement of Web Service Message Contracts with Data

Abstract

Abstract-An increasing number of popular SOAP web services exhibit a stateful behavior, where a successful interaction is determined as much by the correct format of messages as by the sequence in which they are exchanged with a client. The set of such constraints forms a "message contract" that needs to be enforced on both sides of the transaction; it often includes constraints referring to actual data elements inside messages. We present an algorithm for the runtime monitoring of such message contracts with data parameterization. Their properties are expressed in LTL-FO þ , an extension of Linear Temporal Logic that allows first-order quantification over the data inside a trace of XML messages. An implementation of this algorithm can transparently enforce an LTL-FO þ specification using a small and invisible Java applet. Violations of the specification are reported on-the-fly and prevent erroneous or out-of-sequence XML messages from being exchanged. Experiments on commercial web services from Amazon.com and Google indicate that LTL-FO þ is an appropriate language for expressing their message contracts, and that its processing overhead on sample traces is acceptable both for client-side and server-side enforcement architectures.

What Is a Trace? A Runtime Verification Perspective

“…However, it is not common to consider structured events, although such efforts have been seen. For example, in [35] a first-order temporal logic is defined over XML documents where events are structured XML records.…”

“…Monpoly [14] has a plain text format with an event per-line where each line contains a timestamp, event name and then (optionally) some data parameters. Both OCLR-Check [28] and BeepBeep [35] make use of custom XML formats.…”

Scalable Offline Monitoring

“…For example, US hospitals must follow the US Health Insurance Portability and Accountability Act (HIPAA) and financial services must conform to the Sarbanes-Oxley Act (SOX), and these laws even stipulate the use of mechanisms in IT system for monitoring system behavior. Although various monitoring approaches have been developed for different expressive policy specification languages, such as [9,10,13,15,18], they do not scale to checking This work was partly done while Matúš Harvan was at ETH Zurich and Google Inc. and Felix Klaedtke was at ETH Zurich. The Center for Advanced Security Research Darmstadt (www.cased.de), the Zurich Information Security and Privacy Center (www.zisc.ethz.ch), and Google Inc. supported this work.…”

Comprehension of Spacecraft Telemetry Using Hierarchical Specifications of Behavior

“…These systems support various formalisms, such as state machines [14,19,11,7,5], regular expressions [4,19], variations over the µ-calculus [6], temporal logics [6,19,7,15,9,10,12], grammars [19], and rulebased systems [8,17]. Some of these systems focus on being efficient.…”