Documentation for running Octodiff as a library

[liamhughes]

Hello,

I am looking into calling Octodiff from within our C# application.

The README explains how to use the command line utility and I have been able to successful execute the library by calling the Main function of the program, like so:

Octodiff.Program.Main(new string[] { "signature", oldFilePath, outputPath });

I can see the types like Octodiff.Core.SignatureBuilder and Octodiff.Core.DeltaApplier, but would love some documentation on how to use it.

[hnrkndrssn]

Hi Liam,

Thanks for getting in touch! I've put together an example of how to create the signature and delta file and then applying the delta file to create the new file using OctoDiff as a library below:

// Create signature file
var signatureBaseFilePath = @"C:\OctoDiffExample\MyPackage.1.0.0.zip";
var signatureFilePath = @"C:\OctoDiffExample\Output\MyPackage.1.0.0.zip.octosig";
var signatureOutputDirectory = Path.GetDirectoryName(signatureFilePath);
if(!Directory.Exists(signatureOutputDirectory))
    Directory.CreateDirectory(signatureOutputDirectory);
var signatureBuilder = new SignatureBuilder();
using (var basisStream = new FileStream(signatureBaseFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))
using (var signatureStream = new FileStream(signatureFilePath, FileMode.Create, FileAccess.Write, FileShare.Read))
{
    signatureBuilder.Build(basisStream, new SignatureWriter(signatureStream));
}

// Create delta file
var newFilePath = @"C:\OctoDiffExample\MyPackage.1.0.1.zip";
var deltaFilePath = @"C:\OctoDiffExample\Output\MyPackage.1.0.1.zip.octodelta";
var deltaOutputDirectory = Path.GetDirectoryName(deltaFilePath);
if(!Directory.Exists(deltaOutputDirectory))
    Directory.CreateDirectory(deltaOutputDirectory);
var deltaBuilder = new DeltaBuilder();
using(var newFileStream = new FileStream(newFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))
using(var signatureFileStream = new FileStream(signatureFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))
using(var deltaStream = new FileStream(deltaFilePath, FileMode.Create, FileAccess.Write, FileShare.Read))
{
    deltaBuilder.BuildDelta(newFileStream, new SignatureReader(signatureFileStream, new ConsoleProgressReporter()), new AggregateCopyOperationsDecorator(new BinaryDeltaWriter(deltaStream)));
}

// Apply delta file to create new file
var newFilePath2 = @"C:\OctoDiffExample\Output\MyPackage.1.0.1.zip";
var newFileOutputDirectory = Path.GetDirectoryName(newFilePath2);
if(!Directory.Exists(newFileOutputDirectory))
    Directory.CreateDirectory(newFileOutputDirectory);
var deltaApplier = new DeltaApplier { SkipHashCheck = false };
using(var basisStream = new FileStream(signatureBaseFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))
using(var deltaStream = new FileStream(deltaFilePath, FileMode.Open, FileAccess.Read, FileShare.Read))
using(var newFileStream = new FileStream(newFilePath2, FileMode.Create, FileAccess.ReadWrite, FileShare.Read))
{
    deltaApplier.Apply(basisStream, new BinaryDeltaReader(deltaStream, new ConsoleProgressReporter()), newFileStream);
}

I'll also add this to the README to make it easier to find (rather than having to go digging through the issues).

I hope that helps!

Cheers, Henrik

[liamhughes]

Fantastic. Thanks!