In a large online advertising system, adversaries may attempt to profit from the creation of low quality or harmful advertisements. In this paper, we present a large scale data mining effort that detects and blocks such adversarial advertisements for the benefit and safety of our users. Because both false positives and false negatives have high cost, our deployed system uses a tiered strategy combining automated and semi-automated methods to ensure reliable classification. We also employ strategies to address the challenges of learning from highly skewed data at scale, allocating the effort of human experts, leveraging domain expert knowledge, and independently assessing the effectiveness of our system.

Increasingly systems are composed of parts: software components, and the interaction mechanisms (connectors) that enable them to communicate. When assembling systems front independently developed and potentially mismatched parts, wrappers may be used to overcome mismatch as well as to remedy extra-functional deficiencies. Unfortunately the current practice of wrapper creation and use is ad hoc, resulting in artifacts that are often hard to reuse or compose, and whose impact is difficult to analyze. What is needed is a more principled basis for creating, understanding, and applying wrappers. Focusing on the class of connector wrappers (wrappers that address issues related to communication and compatibility), we present a means of characterizing connector wrappers as protocol transformations, modularizing them, and reasoning about their properties. Examples are drawn from commonly practiced dependability enhancing techniques.

Increasingly, systems are composed from independently developed parts, and mechanisms that allow those parts to interact (connectors). In many situations, specialized forms of interaction are needed to bridge component mismatches or to achieve extra-functional properties (e.g., security, performance, reliability), making the design and implementation of these interaction mechanisms a critical issue. Unfortunately, system developers have few options: they must live with available, but often inadequate, generic support for interaction (such as RPC), or they must handcraft specialized mechanisms at great cost. The authors describe a partial solution to this problem, whereby interaction mechanisms are constructed compositionally. Specifically, we describe a set of operators that can transform generic communication mechanisms (such as RPC and publish-subscribe) to incrementally add new capabilities. We show how these transformations can be used to realize complex interactions (such as Kerberized RPC) and to generate implementations of the new connector types at relatively low cost.