= !BluePrint: Mobile Client Peer-to-Peer Synchronization =
[[TOC]]

== Introduction ==
Peer-to-peer sync will enable [http://eden.sahanafoundation.org/wiki/DeveloperGuidelines/EdenMobile EdenMobile] users to synchronize data between their devices without connecting to a server. This will allow mobile users to operate and collaborate more easily in areas where internet access is unreliable or unavailable.

Peer-to-peer sync capabilities exist in [http://developer.servalproject.org/dokuwiki/doku.php?id=content:servalmesh:main_page Serval Mesh] and a number of messaging apps including [https://briarproject.org/ Briar], [https://github.com/casific/murmur Murmur] and [http://whispercomm.org/shout/ Anonymouse].
== Stakeholders ==
!EdenMobile users are the primary stakeholders - they will be able to use P2P sync to share data with each other. The data subjects will also be stakeholders, and appropriate data handling controls to protect the confidentiality, integrity and authenticity of data must be built in. If the server needs to be aware of P2P sync, for example in order to deduplicate data received from mobile clients, then the people deploying and operating the server will also be stakeholders.
== User Stories ==
[https://code.briarproject.org/akwizgran/briar/uploads/655c21456bbc36a83193bdb5e0473f07/SahanaEDENBrambleProjectUseCases.odt User stories]
== Requirements ==
=== Functional requirements===

==== 1. Establishing peer relationships ====

===== 1.1. Peer visibility =====

The P2P sync component '''must''' be able to make the device it is running on visible to nearby devices in order to establish a peer relationship.

===== 1.2. Peer discovery =====

The P2P sync component '''must''' be able to discover nearby devices that have made themselves visible.

===== 1.3. Peer selection =====

When peers have been discovered, the P2P sync component '''must''' allow the user to choose a device to establish a peer relationship with.

===== 1.4. Peer authentication =====

When the user has chosen a device to peer with, the P2P sync component '''must''' allow the user to authenticate the peer before granting the peer access to any resources. The P2P sync component '''may''' allow the user to continue without authenticating the peer.

===== 1.5. Peer persistence =====

When a peer has been authenticated, the P2P sync component '''may''' allow the user to store information about the peer, including information that will allow the peer to be authenticated automatically during subsequent connections. If information about a peer has been stored, the P2P sync component '''must''' allow the user to revoke the peer's access to resources.

==== 2. Destination servers ====

===== 2.1. Destination server configuration =====

The P2P sync component '''may''' allow the user or an administrator to enter the details of a '''destination server''' for the data being synchronized.

==== 3. Data synchronization ====

===== 3.1. Data selection =====

The P2P sync component '''may''' allow the user to choose which data to synchronize, either with peers in general or with each specific peer. When data is received from a peer, the P2P sync component '''may''' automatically choose it for synchronization with other peers.

===== 3.2. Data deletion =====

The P2P sync component '''may''' allow the user to delete data from the device, regardless of whether that data has been chosen for synchronization. The P2P sync component '''may''' automatically delete data that has been received from peers, for example on receiving confirmation that the data has been delivered to a destination server.

==== 4. Managing conflicts ====

===== 4.1. Conflict detection =====

The P2P sync component '''must''' assign an identifier to each item of data chosen for synchronization, such that two peer devices performing synchronization can tell whether they are using the same identifier to refer to different data.

===== 4.2. Conflict resolution =====

When a conflict is detected during synchronization, the P2P sync component '''may''' resolve the conflict automatically, either by merging the conflicting items or by assigning them distinct identifiers. If a conflict cannot be resolved automatically, the P2P sync component '''must''' be able to continue synchronizing other items with the peer. The P2P sync component '''may''' inform the user of conflicts that cannot be resolved automatically.
=== Non-functional ===
http://en.wikipedia.org/wiki/Non-functional_requirements
=== Interoperability ===
=== Standards ===
=== System Constraints ===

== Design ==
<Where relevant include alternative design options>
=== Data Model ===
(e.g. EER or class diagrams)
=== Workflows ===
<Diagrams or Pseudocode> 
=== Site Map ===
<for User Interface solutions>
=== Wireframes ===
<for User Interface solutions>
=== Technologies ===

== Current Implementation ==
<Leave open for a list of existing implementation of this solution in Sahana Eden:>
<*a brief description of the implementation (date/time, name, design options chosen)>
<*a link to the code>
<*list of deployments of the implementation>
<*links to case studies>
<*short analysis of achievements/problems>

== Planned Implementation ==
<List of goals for your implementations which you (include your name/github repo/IRC handle) are currently working on>

== Future Extensions ==
<List of features which could be included, but are outside of the scope of this extension>

== Outstanding Questions ==
<Questions about the features or design that haven't been (and need to be) answered>

== References ==
<Links to external resources>

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BluePrint