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{{{
 The cost and inconvenience of backup are unavoidable and often prohibitive. Large-scale solutions require aggregation of substantial demand to justify the costs of managing a large, centralized repository. Small-scale solutions require significant administrative effort by the end user.
  Due to the low cost of storage, administration is the dominant cost of backup. The only way to make backup affordable is to shift the administrative burden from professionals to individual users. Unfortunately, individual users rarely have the time, patience, or technical expertise to backup their own data properly. If users backup their data at all, snapshots are taken infrequently and incompletely and then only stored locally.
                        from http://mobility.eecs.umich.edu/pastiche/pastiche.html
}}}
The ANGEL APPLICATION (a subproject of [http://missioneternity.org MISSION ETERNITY]) aims to minimize, and ideally eliminate, the administrative and material costs of backing up. It does so by providing a peer-to-peer/social storage infrastructure where people collaborate to back up each other's data. Its goals are (in order of descending relevance to this project)

 * high storage reliability
 * low infrastructure cost
 * ease of use
 * privacy
 * high data availablility
The ANGEL APPLICATION is available under the [http://www.gnu.org/copyleft/gpl.html GPL], with other licensing  schemes available on request.

== Concept ==
We aim to attain the above goals using an open network of peers communicating with each other via a set of verifyable cryptographic messages corresponding to file replication and verification requests. These messages are encapsulated in a subset of the WebDAV protocol. The end-user can interact with the angel-application in the same way she could with any (WebDAV-based) network file system: encryption, checksumming and replication are handled transparently. See the [http://svn.gna.org/viewcvs/*checkout*/angel-app/trunk/angel-app/doc/report/m221e-angel-app-0.2.pdf Technical Report] for details.

== Status ==

A release candidate of the upcoming beta-version is currently operational at [http://missioneternity.org:6221/ http://missioneternity.org:6221]. This version has undergone an extensive security and stability review and is expected to be stable.

== Get Started ==
[[Anchor(download)]]

 * ["Download"]: provides access the source code, or to ready-to-run downloads where available.
 * [:Documentation/Install:Installation]: provides access the source code, or to ready-to-run downloads where available.
 * ["Documentation"]: learn about the underlying principles and programming interfaces of the ANGEL APPLICATION.
 * [:Contributing:Contribute]: we're always looking for contributors. Log in and start editing.
== News ==
Announcements and development news are posted to the [http://www.etoy.com/blog/archive/tag/angel-app/ etoy.VENTURE ASSOCIATION's blog].