FileBufferReader is a JavaScript library reads file and returns chunkified array-buffers. The resulting buffers can be shared using WebRTC data channels or socket.io.
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README.md

FileBufferReader.js / Demo / Watch a YouTube video

npm downloads Build Status: Linux

All released versions: https://github.com/muaz-khan/FileBufferReader/releases

Using FileBufferReader.js, you can:

  1. Get list of array-buffers with each specific chunkSize
  2. Chunks can be step-by-step shared with remote peers, or instantly shared using for-loop

You can easily implement retransmission of chunks as well. You need to set binaryType to arraybuffer:

WebRTC_Data_Channel.binaryType = 'arraybuffer';

A few points:

  1. FileBufferReader itself doesn't do anything except reading the file(s)
  2. You need to manually share chunks using your preferred medium or gateway
  3. FileBufferReader currently uses memory to store chunks; which has storage limits. So, you may not be able to use FileBufferReader to read/share file with 1GB size or more.
  4. FileBufferReader is added to support controlled-buffers transmissions whilst following Skype's file sharing style.

It is MIT Licenced, which means that you can use it in any commercial/non-commercial product, free of cost.

npm install fbr --production

# or using bower
bower install fbr

To use it:

<script src="./node_modules/fbr/FileBufferReader.js"></script>

<!-- or CDN -->
<script src="https://cdn.webrtc-experiment.com/FileBufferReader.js"></script>

Or run localhost server:

node server.js

Then open: http://localhost:9001/ or http://127.0.0.1:9001/.

fbr-client

You can even try socket.io file sharing client:

npm install fbr-client

Then run the server:

cd ./node_modules/fbr-client
node server.js port=9001

Then open: http://localhost:9001/ or http://127.0.0.1:9001/.

You can modify development files from the dev directory; and use grunt tool to recompile into FileBufferReader.js.

FileBufferReader API

  1. chunks object. It contains multiple files' chunks. Even if you received chunks from remote peer, and invoked addChunk method; all chunks will be stored in same chunks object. var fileChunks = fileBufferReader.chunks['file-uuid'].
  2. readAsArrayBuffer method. It reads entire file and stores chunkified buffers in chunks object.
  3. getNextChunk method. It simply reads last-position and returns next available array-buffer chunk.
  4. onBegin, onEnd and onProgress events. These are added only to support file progress bars.
  5. addChunk method. It allows you store all received chunks in an array until entire file is received.
  6. convertToObject method. FileBufferReader assumes that you're sending ArrayBuffer using WebRTC data channels. It means that you'll be getting ArrayBuffer type in the onmessage event. convertToObject method allows you convert ArrayBuffer into JavaScript object type, which is helpful to check type of message.
  7. convertToArrayBuffer method. You can pass javascript object or any data-type, and this method will return ArrayBuffer.

1. Link The Library

https://cdn.webrtc-experiment.com/FileBufferReader.js

# or
https://cdn.rawgit.com/muaz-khan/FileBufferReader/master/FileBufferReader.js

2. Select File (optional step)

You can use input[type=file].onchange instead, which is strongly recommended over using FileSelecter because FileSelector object is incapable to handle failures or situations where browser doesn't fires onchange event.

var fileSelector = new FileSelector();

// *.png, *.jpeg, *.mp4, etc.
fileSelector.accept = '*.*';

var btnSelectFile = document.getElementById('select-file');
btnSelectFile.onclick = function() {
    fileSelector.selectSingleFile(function(file) {
        // file == input[type=file]
    });
};

3. Read Buffers

var fileBufferReader = new FileBufferReader();

fileBufferReader.readAsArrayBuffer(file, function(fileUUID) {
    // var file         = fileBufferReader.chunks[fileUUID];
    // var listOfChunks = file.listOfChunks;

    // get first chunk, and send using WebRTC data channels
    // NEVER send chunks in loop; otherwise you'll face issues in slow networks
    // remote peer should notify if it is ready for next chunk
    fileBufferReader.getNextChunk(fileUUID, function(nextChunk, isLastChunk) {
        if(isLastChunk) {
            alert('File Successfully sent.');
        }
        // sending using WebRTC data channels
        datachannel.send(nextChunk);
    });
});

readAsArrayBuffer takes 3rd argument as well; where you can pass chunkSize, and your custom data.

var extra = {
    chunkSize: 15 * 1000,    // Firefox' receiving limit is 16k
    userid: 'sender-userid'  // MOST USEFUL object
};

fileBufferReader.readAsArrayBuffer(file, callback, extra);

4. When remote peer receives a chunk

datachannel.onmessage = function(event) {
    var chunk = event.data;

    if (chunk instanceof ArrayBuffer || chunk instanceof DataView) {
        // array buffers are passed using WebRTC data channels
        // need to convert data back into JavaScript objects

        fileBufferReader.convertToObject(chunk, function(object) {
            datachannel.onmessage({
                data: object
            });
        });
        return;
    }

    // if you passed "extra-data", you can access it here:
    // chunk.extra.senderUserName or whatever else

    // if target peer requested next chunk
    if(chunk.readyForNextChunk) {
        fileBufferReader.getNextChunk(chunk.uuid, function(nextChunk, isLastChunk) {
            if(isLastChunk) {
                alert('File Successfully sent.');
            }
            // sending using WebRTC data channels
            datachannel.send(nextChunk);
        });
        return;
    }

    // if chunk is received
    fileBufferReader.addChunk(chunk, function(promptNextChunk) {
        // request next chunk
        datachannel.send(promptNextChunk);
    });
};

5. File progress helpers

Link this script:

https://cdn.webrtc-experiment.com/FileProgressBarHandler.js

# or
https://cdn.rawgit.com/muaz-khan/FileBufferReader/master/fbr.0/dev/FileProgressBarHandler.js

Add a files-div:

<div id="files-container"></div>

Add following code:

// this line is optional
// however it allows you set the <DIV> for progress-bars and files-preview
fileBufferReader.filesContainer = document.getElementById('files-container');

// this line sets "onFileStart", "onFileProgress" and "onFileEnd" events (see below lines)
FileProgressBarHandler.handle(fileBufferReader);

fileBufferReader.onBegin    = fileBufferReader.onFileStart;
fileBufferReader.onProgress = fileBufferReader.onFileProgress;
fileBufferReader.onEnd      = fileBufferReader.onFileEnd;

Above snippet can be written as following:

var options = {};

// this line is optional
// however it allows you set the <DIV> for progress-bars and files-preview
options.filesContainer = document.getElementById('files-container');

// this line sets "onFileStart", "onFileProgress" and "onFileEnd" events (see below lines)
FileProgressBarHandler.handle(options);

fileBufferReader.onBegin    = options.onFileStart;
fileBufferReader.onProgress = options.onFileProgress;
fileBufferReader.onEnd      = options.onFileEnd;

If you're NOT interested in above FileProgressBarHandler.js:

var progressHelper = {};
var outputPanel = document.body;

var FileHelper = {
    onBegin: function(file) {
        // if you passed "extra-data", you can access it here:
        // file.extra.senderUserName or whatever else

        var li = document.createElement('li');
        li.title = file.name;
        li.innerHTML = '<label>0%</label> <progress></progress>';
        outputPanel.insertBefore(li, outputPanel.firstChild);
        progressHelper[file.uuid] = {
            li: li,
            progress: li.querySelector('progress'),
            label: li.querySelector('label')
        };
        progressHelper[file.uuid].progress.max = file.maxChunks;
    },
    onEnd: function(file) {
        // if you passed "extra-data", you can access it here:
        // file.extra.senderUserName or whatever else

        progressHelper[file.uuid].li.innerHTML = '<a href="' + file.url + '" target="_blank" download="' + file.name + '">' + file.name + '</a>';
    },
    onProgress: function(chunk) {
        // if you passed "extra-data", you can access it here:
        // chunk.extra.senderUserName or whatever else

        var helper = progressHelper[chunk.uuid];
        helper.progress.value = chunk.currentPosition || chunk.maxChunks || helper.progress.max;
        updateLabel(helper.progress, helper.label);
    }
};

function updateLabel(progress, label) {
    if (progress.position == -1) return;
    var position = +progress.position.toFixed(2).split('.')[1] || 100;
    label.innerHTML = position + '%';
}

fileBufferReader.onBegin    = FileHelper.onBegin;
fileBufferReader.onProgress = FileHelper.onProgress;
fileBufferReader.onEnd      = FileHelper.onEnd;

Sharing with multiple users?

fbr.readAsArrayBuffer(file, function(fileUUID) {
    ['first-user', 'second-user', 'third-user'].forEach(function(userid) {
        fbr.getNextChunk(fileUUID, function(nextChunk, isLastChunk) {
            specific_datachannel.send(nextChunk);
        }, userid);
    });
});

datachannel.onmessage = function(event) {
    fbr.getNextChunk(message.uuid, function(nextChunk, isLastChunk) {
        specific_datachannel.send(nextChunk);
    }, specific_userid);
};

Pass specific-userid as 3rd argument over getNextChunk method.

To uniquely identify progress-bars for each user, watch for remoteUserId object:

FileHelper.onBegin = function(file) {
    if(file.remoteUserId) {
        // file is being shared with multiple users
    }
};

FileHelper.onEnd = function(file) {
    if(file.remoteUserId) {
        // file is being shared with multiple users
    }
};

FileHelper.onProgress = function(chunk) {
    if(chunk.remoteUserId) {
        // file is being shared with multiple users
    }
};

Advance Usages

var fbr = new FileBufferReader();
fbr.readAsArrayBuffer(file, function(fileUUID) {
    // don't call "getNextChunk"
    // instead, try to process/use/acccess chunks yourself

    var thisFileChunks = fbr.chunks[fileUUID];
    var numberOfFileChunks = thisFileChunks[0].maxChunks;

    var arrayOfRealBuffers = [];

    for(var i = 1; i < numberOfFileChunks; i++) {
        var fileChunk = thisFileChunks[i];
        var realArrayBufferObject = fileChunk.buffer;
        arrayOfRealBuffers.push(realArrayBufferObject);
    }

    var fileBlob = new Blob(realArrayBufferObject, {
        type: thisFileChunks[0].type
    });

    var blobURL = URL.createObjectURL(fileBlob);
    document.write('<iframe style="width: 100%; height: 100%; border:0; " src="' +  blobURL + '"></iframe>');
});

The structure of fileBufferReader.chunks object looks like this:

fileBufferReader.chunks =
{
    // "4152661527041346" is file-uuid
   "4152661527041346":{

      // "0" index helps firing "onStart" event.
      "0":{
         "currentPosition":0,
         "uuid":"4152661527041346",
         "maxChunks":20,
         "size":298540,
         "name":"WebRTC.png",
         "type":"image/png",
         "lastModifiedDate":"Wed Oct 14 2015 15:51:26 GMT+0500 (PKT)",
         "start":true,
         "userid":0,
         "extra":{
            "userid":0
         }
      },

      // index "1" to "maxChunks" are the real file-chunks

      "1":{
         "uuid":"4152661527041346",

         // this is the real ArrayBuffer object
         "buffer":{},

         "currentPosition":1,
         "maxChunks":20,
         "size":298540,
         "name":"WebRTC.png",
         "lastModifiedDate":"Wed Oct 14 2015 15:51:26 GMT+0500 (PKT)",
         "type":"image/png",
         "userid":0,
         "extra":{  
            "userid":0
         }
      },

      ....
      ....

      // this is the last file-chunk
      // here "currentPosition===maxChunks"
      "20":{  
         "uuid":"4152661527041346",
         "buffer":{},
         "currentPosition":20,
         "maxChunks":20,
         "size":298540,
         "name":"WebRTC.png",
         "lastModifiedDate":"Wed Oct 14 2015 15:51:26 GMT+0500 (PKT)",
         "type":"image/png",
         "userid":0,
         "extra":{  
            "userid":0
         }
      },

      // this one helps firing "onEnd" event
      "21":{  
         "currentPosition":21,
         "uuid":"4152661527041346",
         "maxChunks":20,
         "size":298540,
         "name":"WebRTC.png",
         "lastModifiedDate":"Wed Oct 14 2015 15:51:26 GMT+0500 (PKT)",
         "url":"blob:http%3A//domain/fe5a20d0-cdb4-4f4e-9de7-1a14340fc402",
         "type":"image/png",
         "end":true,
         "userid":0,
         "extra":{  
            "userid":0
         }
      },

      // this is optionally used to detect which chunk is being shared
      // you should skip it.
      "currentPosition":0
   }
}

You can see that real file-chunks starts from 1 and ends before length-1.

E.g.

var fileChunks = fbr.chunks['file-uuid'];
var allFileIndices = Object.keys(fileChunks);

var allFileBuffers = [];
for(var chunkIndex = 1; chunkIndex < allFileIndices.length; i++) {
    var chunk = fileChunks[chunkIndex];
    allFileBuffers.push(chunk.buffer);
}

FileConverter

This global object exposes two methods:

  1. ConvertToArrayBuffer
  2. ConvertToObject

Here is how to use these methods:

var yourObject = {
    x: 0,
    y: 1,
    str: 'string',
    bool: true
};

FileConverter.ConvertToArrayBuffer(yourObject, function(arrayBuffer) {
    alert(arrayBuffer.byteLength);

    // to convert back to "object"
    FileConverter.ConvertToObject(arrayBuffer, function(yourObject) {
        alert( JSON.stringify(yourObject) );
    });
});

When you call getNextChunk, the FileBufferReader instance checks for currentPosition and returns buffer using following snippet:

// this method explains insights of FileBufferReader
fbr.getNextChunk = function(fileUUId, callback) {
    var fileChunks = fbr.chunks[fileUUID];
    var currentPosition = fileChunks.currentPosition;

    var nextChunk = fileChunks[currentPosition];
    FileConverter.ConvertToArrayBuffer(nextChunk, function(buffer) {
        // you can see that "callback" is passed two arguments
        // 1) the converted buffer
        // 2) "isLastChunk" boolean
        callback(buffer, currentPosition == nextChunk.maxChunks);
    });
};

// and your code calls above method as following;
fbr.getNextChunks('file-uuid', function(buffer) {
    webrtc.channel.send(buffer);
});

Applications using FileBufferReader

  1. RTCMultiConnection.js

RTCMultiConnection FileBufferReader Demos

  1. https://rtcxp.com/fs
  2. https://rtcmulticonnection.herokuapp.com/demos/Audio+Video+TextChat+FileSharing.html
  3. https://rtcmulticonnection.herokuapp.com/demos/TextChat+FileSharing.html

More demos here: https://rtcmulticonnection.herokuapp.com/demos/

License

FileBufferReader.js is released under MIT licence . Copyright (c) Muaz Khan.