openhome / ohGit

OpenHome Git Library

ohGit

ohGit is a library for fetching a git using the git protocol and reading its contents.

It is written in C#, and is compatible with both .Net and Mono.

ohGit depends on SharpZipLib from ic#code, which is included as a library.

Getting Started

The starting point is the Factory class.

public class Factory
{
    public static IRepository InitialiseRepository(string aPath, string aBranch)
    {
        return (Repository.Initialise(aPath, aBranch));
    }

    public static IRepository OpenRepository(string aPath)
    {
        return (new Repository(aPath));
    }

    public static bool Fetch(IRepository aRepository, string aUri)
    {
        return (Fetcher.Fetch(aRepository, aUri));
    }
}

To open an existing repository, use OpenRepositiory(), providing the path to the folder that contains the .git folder.

To initialise a new repository, use InitialiseRepository(), providing a path and the name of the HEAD branch. You may then use Fetch() to collect its contents using the git protocol.

Either way, you now have an IRepository:

public interface IRepository
{
    IDictionary<string, IBranchRef> Branches { get; }
    IDictionary<string, IRef> Refs { get; }
}

Reading

It is necessary to have a basic understanding of the low-level structure of a git to understand the folowing collection of interfaces. They expose this structure in a way that facilitates complete traversal of all branches and their parents.

IRepository has an IDictionary for getting an IBranch ...

public interface IBranch
{
    string Name { get; }
    ICommit Commit { get; }
    IChange CreateChange();
    bool IsEmpty { get; }
}

... from which its ICommit can be read ...

public interface ICommit : IObject
{
    ITree Tree { get; }
    ICollection<ICommit> Parents { get; }
    IPersonTime Author { get; }
    IPersonTime Committer { get; }
    string Description { get; }
}

... from which its ITree can be read ...

public interface ITree : IObject
{
    ICollection<ITreeEntry> Items { get; }
}

... from which its ITreeEntry items can be read ...

public interface ITreeEntry : IObject
{
    string Name { get; }
    string Mode { get; }
    IObject Item { get; }
}

Using the Item member an IObject can be retrieved, which may be a further ITree, or an IBlob.

public interface IBlob : IObject
{
    byte[] Contents { get; }
}

Usage

This library is currently used by ohMediaToolkit to collect a remotely updated description of its media tree. It is envisaged that the library could be very useful for connecting a software developer to all installations of their app, allowing them to distribute richer content than they could with, for instance, an RSS feed.

i.e. plugins, blacklists/whitelists, examples, seasonal skins, etc