Multipart Upload Initiating

lib/knox/client.js

@@ -123,6 +123,74 @@ Client.prototype.put = function(filename, headers){
   return this.request('PUT', filename, headers);
 };
 
+/**
+ * Represens chunk builder that concatenates string chunks in the readable stream.
+ * @constructor
+ */
+function ChunkBuilder(){
+	this.data = '';
+	this.completed = false;
+	this.error = null;
+	this.append_chunk = function(chunk) { this.data += chunk }.bind(this);
+	this.complete = function() { this.completed = true }.bind(this);
+	this.catch_error = function(e) { this.error = e; this.completed = true }.bind(this);
+}
+
+/**
+ * Returns value of the XML element.
+ * @param {String} content XML document.
+ * @param {String} elementName The name of the XML element.
+ * @returns {String} Value of the specified XML element.
+*/
+function get_element_content(content, elementName){
+	var xmltag = '<' + elementName + '>';
+	var startpos = content.indexOf(xmltag) + xmltag.length;
+	xmltag = '</' + elementName + '>';
+	var endpos = content.indexOf(xmltag);
+	return content.substring(startpos, endpos);
+}
+
+/**
+ * Represents uploading initialization data.
+ * @param {String} rawxml XML markup accepted from Amazon S3 service. See http://docs.amazonwebservices.com/AmazonS3/latest/API/index.html?mpUploadInitiate.html
+ * @constructor
+ */
+function UploadInitResult(rawxml){
+	this.bucket = null;
+	this.key = null;
+	this.upload_id = null;
+	if(typeof rawxml == 'string'){
+		//The first, let's find Bucket name in the entire XML
+		this.bucket = get_element_content(rawxml, 'Bucket');
+		this.key = get_element_content(rawxml, 'Key');
+		this.upload_id = get_element_content(rawxml, 'UploadId');
+	}
+}
+
+/**
+ * Initiates multipart upload.
+ * @param {String} filename The name of the object on Amazon S3 service.
+ * @param {Object} headers Additional headers used in HTTP request to S3 service.
+ * @param {Function} fn A callback that accepts two parameters: err that holds exception info, and ir - multipart upload initiation result.
+ */
+Client.prototype.begin_upload = function(filename, headers, fn){
+	if(typeof headers == 'function') fn = headers;
+	filename += '?uploads';	//initiate uploading transaction, see http://docs.amazonwebservices.com/AmazonS3/latest/API/mpUploadInitiate.html
+	var request = this.request('POST', filename, headers);
+	//Upload initiating returns XML document in UTF-8 encoding that contains uploading ID.
+	request.on('response', function(response){
+		response.setEncoding('utf8');	//TODO: Encoding may be detected in more flexible way (or detected automatically).
+		if(response.statusCode != 200) fn({'statusCode': response.statusCode}, null);
+		else{
+			var builder = new ChunkBuilder();	//used for chunk concatenation.
+			response.on('data', function(chunk) { builder.append_chunk(chunk) });	//save chunks into the builder.
+			response.on('error', function(err) { builder.catch_error(err) });	//register error.
+			response.on('end', function(){ builder.complete(); fn(builder.error, new UploadInitResult(builder.data)); });
+		}
+	});
+	request.end();
+};
+
 /**
  * PUT the file at `src` to `filename`, with callback `fn`
  * receiving a possible exception, and the response object.