Dalesa
Encyclopedia
Dalesa is a peer-to-peer
web cache
designed for Local Area Networks (LAN). Dalesa is a free and opensource software developed by Lanka Software Foundation under GPL license.
which act as a web proxy in every participating node. If a web request misses the local cache then the system fail-back to multicast based lookup protocol to query the P2P network, if any other node on the network gives a positive response to this query then the web object will be fetched from that node.
it is possible to encapsulate numerous group communication mechanisms like Distributed Hash Table
s other than currently available IP multicast
ing based protocol. The protocol identifies web objects by the SHA-1 hash of their origin URLs, this approach has reduced the size of UDP datagrams multicasted over the network carrying information related to URLs which are typically quite lengthier than 160 bits these days.
Peer-to-peer
Peer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads among peers. Peers are equally privileged, equipotent participants in the application...
web cache
Web cache
A web cache is a mechanism for the temporary storage of web documents, such as HTML pages and images, to reduce bandwidth usage, server load, and perceived lag...
designed for Local Area Networks (LAN). Dalesa is a free and opensource software developed by Lanka Software Foundation under GPL license.
Introduction
Dalesa can be used as an alternative to centralized web caches in a Local Area Network. This is done by exposing local web browser caches to the entire P2P network. This is achieved through a daemon (computer software)Daemon (computer software)
In Unix and other multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user...
which act as a web proxy in every participating node. If a web request misses the local cache then the system fail-back to multicast based lookup protocol to query the P2P network, if any other node on the network gives a positive response to this query then the web object will be fetched from that node.
Architecture
Dalesa web cache has two major components. The core of the system is libdalesa, it is the core library that acts as a group communication framework. The other component is a web cache that uses libdalesa for remote cache object lookups. libdalesa is a generic framework for group communication which currently . As an abstraction layerAbstraction layer
An abstraction layer is a way of hiding the implementation details of a particular set of functionality...
it is possible to encapsulate numerous group communication mechanisms like Distributed Hash Table
Distributed hash table
A distributed hash table is a class of a decentralized distributed system that provides a lookup service similar to a hash table; pairs are stored in a DHT, and any participating node can efficiently retrieve the value associated with a given key...
s other than currently available IP multicast
Multicast
In computer networking, multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source creating copies automatically in other network elements, such as routers, only when the topology of the network requires...
ing based protocol. The protocol identifies web objects by the SHA-1 hash of their origin URLs, this approach has reduced the size of UDP datagrams multicasted over the network carrying information related to URLs which are typically quite lengthier than 160 bits these days.
Awards & Grants
- Dalesa was awarded with an ICTA (Sri Lanka) eSociety grant in 2009.
- Dalesa won an special mention award at ICTA e-Swabhimani 2009 National Awards 2009.
Releases
- Dalesa-1.0.0-rc1 was released in January 2010.
- Dalesa-1.1.0 was released in August 2010.
Problems
- Security and integrity are the major problems in Dalesa. As it has no mechanism to verify integrity and authenticity of cache objects, content poisoning attacks are possible. In a content poisoning attack a rouge user can respond to a lookup message and force the requester to fetch a malicious file from his node.