repo-ng

Repo Protocol Specification

===========================

Repo is persistent storage of data objects model in NDN. The NDN repo protocol is a specification of repo operations including reading, insertion and deletion of data objects in repo.

Repo semantics is based on [Command Interests](http://redmine.named-data.net/projects/nfd/wiki/Command_Interests) with signed commponents an the end of the name and basic common semantics of NDN. 

When some operation of repo including insertion and deletion of data objects is requested, a starter interest is sent. The starter interest is the interest as command of insertion and deletion and signed as form of command interest for access control. The repo will response the command with the data object.

The repo protocol can be categorized in three sections of reading, insertion and deletion of data objects.

## Repo Reading Specification

The repo could be viewed as the data container of the data objects. It will register some specific prefixes of data objects it holds into NFD (NDN Forwarding Deamon). The prefix of data objects that repo will respond will following such semantics.

### Semantics of data objects that repo manages

The name semantics is defined to have following components,:

* ``<box of repo>`` refers to specific name of repo

* ``%R`` refers to data objects

* ``<data name>`` refers to specific name of data

<box of repo> and <data name> can be divided by serveral continious ``/`` according to specific defination.

For example, for ``<box of repo>`` as ``/ucla/cs/repo`` and ``<data name>`` as ``/vedio/Forrest Gump/s1/v1``, the data object is defined as following:

     /ucla/cs/repo/%R/vedio/Forrest Gump/s1/v1

A standard interest with such semantics is used to fetch content from the repo. The repo will respond when the name of the interest matches the prefix it registered in NFD. If the content in repo matches the interests, it will respond with the data object. When the interest is not matched, it will not respond.

The protocol is listed as bellow

If there is a matching data object:

    Requester                     Repo

        |                           |

        |                           |

        |         Interest          |

     t1 |-------------------------->|

        |                           |

        |        Data Object        |

     t2 |<==========================|

        |                           |

        |                           |

        |                           |

If there is no matching data object:

    Requester                     Repo

        |                           |

        |                           |

        |         Interest          |

     t1 |-------------------------->|

        |                           |

        |                           |

        |                           |