Prakash Linga

Kelips: Building an efficient and stable P2P DHT through increased memory and background overhead

A peer-to-peer (p2p) distributed hash table (DHT) system allows hosts to join and fail silently (or leave), as well as to insert and retrieve files (objects). This paper explores a new point in design space in which increased memory usage and constant background communication overheads are tolerated to reduce file lookup times and increase stability to failures and churn. Our system, called Kelips, uses peer-to-peer gossip to partially replicate file index information. In Kelips, (a) under normal conditions, file lookups are resolved within 1 RPC, independent of system size, and (b) membership changes (e.g., even when a large number of nodes fail) are detected and disseminated to the system quickly. Per-node memory requirements are small in medium-sized systems. When there are failures, lookup success is ensured through query rerouting. Kelips achieves load balancing comparable to existing systems. Locality is supported by using topologically aware gossip mechanisms. Initial results of an ongoing experimental study are also discussed.

Querying peer-to-peer networks using P-trees

We propose a new distributed, fault-tolerant peer-to-peer index structure called the <B>P-tree</B>. P-trees efficiently evaluate range queries in addition to equality queries.

P-ring: an efficient and robust P2P range index structure

Peer-to-peer systems have emerged as a robust, scalable and decentralized way to share and publish data. In this paper, we propose P-Ring, a new P2P index structure that supports both equality and range queries. P-Ring is fault-tolerant, provides logarithmic search performance even for highly skewed data distributions and efficiently supports large sets of data items per peer. We experimentally evaluate P-Ring using both simulations and a real distributed deployment on PlanetLab, and we compare its performance with Skip Graphs, Online Balancing and Chord.

P-tree: a p2p index for resource discovery applications

We propose a new distributed, fault-tolerant Peer-to-Peer index structure for resource discovery applications called the P-tree. P-trees efficiently support range queries in addition to equality queries.

Guaranteeing correctness and availability in P2P range indices

New and emerging P2P applications require sophisticated range query capability and also have strict requirements on query correctness, system availability and item availability. While there has been recent work on developing new P2P range indices, none of these indices guarantee correctness and availability. In this paper, we develop new techniques that can provably guarantee the correctness and availability of P2P range indices. We develop our techniques in the context of a general P2P indexing framework that can be instantiated with most P2P index structures from the literature. As a specific instantiation, we implement P-Ring, an existing P2P range index, and show how it can be extended to guarantee correctness and availability. We quantitatively evaluate our techniques using a real distributed implementation.

Load Balancing and Range Queries in P2P Systems Using P-Ring

In peer-to-peer (P2P) systems, computers from around the globe share data and can participate in distributed computation. P2P became famous, and infamous, due to file-sharing systems like Napster. However, the scalability and robustness of these systems make them appealing to a wide range of applications. This article introduces P-Ring, a new peer-to-peer index structure. P-Ring is fully distributed, fault tolerant, and provides load balancing and logarithmic search performance while supporting both equality and range queries. Our theoretical analysis as well as experimental results, obtained both in a simulated environment and on PlanetLab, show the performance of our system.

An indexing framework for peer-to-peer systems

Current peer-to-peer (P2P) indices are monolithic pieces of software that address only a subset of the desired functionality for P2P databases. For instance, Chord [6] provides reliability and scalability, but only supports equality queries. Skip Graphs [1] support equality and range queries, but only for one data item per peer. PePeR [4] supports equality and range queries over multiple data items per peer, but does not provide any search or reliability guarantees in face of multiple failures. Galanis et al. [5] describe an index structure for locating XML documents, but this index does not provide any provable guarantees on size and performance. In a P2P database system, all of the above functionality is required, but none of the existing systems supports it. We devise a modularized indexing framework that cleanly separates different functional components. This allows us to reuse existing algorithms rather than implement everything anew and to experiment with different implementations for the same component so that we can clearly evaluate and quantify the benefits of a particular implementation. Our indexing framework has the following components: 1. Fault-tolerant Torus: Provides fault-tolerant connectivity among peers. 2. Data Store: Stores actual data and provides methods for reliably exchanging data items between peers. 3. Replication Manager: Ensures data items are stored reliably even in the face of peer failures. 4. Content Router: Allows efficient location of data items.

A storage and indexing framework for p2p systems

We present a modularized storage and indexing framework that cleanly separates the functional components of a P2P system, enabling us to tailor the P2P infrastructure to the specific needs of various Internet applications eat, without having to devise completely new storage management and index structures for each application.