Modern Web services rely extensively upon a tier of in-memory caches to reduce request latencies and alleviate load on backend servers. Within a given cache, items are typically partitioned across cache servers via consistent hashing, with the goal of balancing the number of items maintained by each cache server. Effects of consistent hashing vary by associated hashing function and partitioning ratio. Most real-world workloads are also skewed, with some items significantly more popular than others. Inefficiency in addressing both issues can create an imbalance in cache-server loads.

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High-bandwidth, semi-private optical lambda networks carry growing volumes of data on behalf of large data centers, both in cloud computing environments and for scientific, financial, defense, and other enterprises. This paper undertakes a careful examination of the end-to-end characteristics of an uncongested lambda network running at high speeds over long distances, identifying scenarios associated with loss, latency variations, and degraded throughput at attached end-hosts. We use identical fast commodity source and destination platforms, hence expect the destination to receive more or less what we send. We observe otherwise: degraded performance is common and easily provoked. In particular, the receiver loses packets even when the sender employs relatively low data rates. Data rates of future optical network components are projected to outpace clock speeds of commodity end-host processors, hence more and more end-to-end applications will confront the same issue we encounter. Our work thus poses a new challenge for those hoping to achieve dependable performance in higher-end networked settings.

We design and implement a novel class of highly precise network instrumentation and apply this tool to perform the first exact packet-timing measurements of a wide-area network ever undertaken, capturing 10 Gigabit Ethernet packets in flight on optical fiber. Through principled design, we improve timing precision by two to six orders of magnitude over existing techniques. Our observations contest several common assumptions about behavior of wide-area networks and the relationship between their input and output traffic flows. Further, we identify and characterize emergent packet chains as a mechanism to explain previously observed anomalous packet loss on receiver endpoints of such networks.

The most commonly deployed web service applications employ client-server communication patterns, with clients running remotely and services hosted in data centers. In this paper, we make the case for Service-Oriented Collaboration applications that combine service-hosted data with collaboration features implemented using peer-to-peer protocols. Collaboration features are awkward to support solely based on the existing web services technologies. Indirection through the data center introduces high latencies and limits scalability, and precludes collaboration between clients connected to one-another but lacking connectivity to the data center. Cornellpsilas Live Distributed Objects platform combines web services with direct peer-to-peer communication to eliminate these issues.