Sample C# Azure Function App to upload two binary files and compare them byte-by-byte

Implementation Tech Stack

• C# 7
• .NET Standard 2.0, .NET Core 2.0
• Azure Blob Storage
• Azure Functions v2.0 Beta

Usage Workflow

1. Encode the two binaries that you need to compare as Base64 string.
2. Put these Base64 strings to JSON into data field.
3. Pick an ID for the comparison.
4. Send the binaries with PUT request to /v1/diff/:id/left and /v1/diff/:id/right URLs.
5. Receive the comparison result with GET request to /v1/diff/:id URL.

A test version of this application is deployed to https://binarycompare.azurewebsites.net base URL.

API

Upload Binary

Upload binary as left or right object for comparison.

• URL

  /v1/diff/:id/left and /v1/diff/:id/right

• Method:

  PUT

• URL Params

  id=[string] - difference ID that you pick, to be used when requesting the difference

• Content

  { "data": "<base64 encoded binary>" }

• Success Response:

  • Code: 200
    Binary was uploaded successfully

• Error Response:

  • Code: 404 NOT FOUND
    URL is not correct

  OR

  • Code: 400 BAD REQUEST
    Missing or invalid data parameter in the request body
    Content: "Reason explaining why the request was not valid"

• Sample HTTP Request:

  PUT /v1/diff/sampleid/left HTTP/1.1
  Content-Type:application/json
  Accept:application/json
  
  {"data":"AQIDBAUGBwgJAA=="}
  

Get Comparison Result

Get the comparison result of 2 previously uploaded binaries (left and right).

• URL

  /v1/diff/:id

• Method:

  GET

• URL Params

  id=[string] - difference ID, which was used to upload the two binaries to compare

• Success Response:

  • Code: 200
    Comparison is successful
    
    Content when binaries are exactly the same:
    {"result":"same"}
    
    Content when binaries have different length:
    {"result":"size-differs"}
    
    Content when binaries have the same length but some differences exist (example):

    { 
      "result":"different", 
      "differences": [
         { "startIndex": 5, "length": 2 },
         { "startIndex": 11, "length": 1 }
      ]
    }`
    

    Both startIndex and length refer to each byte separately.

• Error Response:

  • Code: 404 NOT FOUND
    One or both binaries with requested ID were not uploaded yet

• Sample HTTP Request:

  GET /v1/diff/sampleid HTTP/1.1
  Content-Type:application/json
  Accept:application/json
  

Running Locally

• Make sure that you have a proper Azure Storage connection string in local.settings.json
• dotnet restore to restore NuGet packages
• dotnet build to build the solution
• dotnet publish to publish the binaries
• cd BinaryDiff then func start --script-root bin\\debug\\netstandard2.0\\publish to start Function App locally
• dotnet test 'BinaryDiff.Tests\\BinaryDiff.Tests.csproj' to run tests (Integration Test required Function App to be running)

If you are using Visual Studio Code, it has predefined commands for running Function App and Tests directly in editor's console.