b2_start_large_file

Prepares for uploading the parts of a large file.

Warning: Do not include Protected Health Information (PHI) or Personally Identifiable Information (PII) in bucket names, object/file/folder names, or other metadata. Such metadata is not encrypted in a way that meets Health Insurance Portability and Accountability Act (HIPAA) protection requirements for PHI/PII data and is not generally encrypted in client-side encryption architectures.

Request

Request HTTP Headers

Authorization

required

An account authorization token, obtained from b2_authorize_account. The token must have the writeFiles capability.

Request HTTP Message Body Parameters

bucketId

required

The ID of the bucket that the file will go in.

fileName

required

The name of the file. See Files for requirements on file names.

contentType

required

The MIME type of the content of the file, which will be returned in the Content-Type header when downloading the file. Use the Content-Type b2/x-auto to automatically set the stored Content-Type post upload. In the case where a file extension is absent or the lookup fails, the Content-Type is set to application/octet-stream. The Content-Type mappings can be perused here.

customUploadTimestamp

optional

If this is present, B2 will use it as the value of the upload timestamp. The value should be a base 10 number that represents a UTC time when the original source file was uploaded. It is a base 10 number of milliseconds since midnight, January 1st, 1970 UTC. This fits in a 64-bit integer, such as the type long in Java, and so it can be passed directly into the Java call Date.setTime(long time). The value must not use a date that is set to a time in the future. If the value is null, it will be ignored.
NOTE: If you need to use this feature, please contact Backblaze support to have the feature enabled on your account.

fileInfo

optional

A JSON object holding the name/value pairs for the custom file info.

If the original source of the file being uploaded has a last modified time concept, Backblaze recommends using src_last_modified_millis as the name, and a string holding the base 10 number number of milliseconds since midnight, January 1, 1970 UTC. This fits in a 64 bit integer such as the type "long" in the programming language Java. It is intended to be compatible with Java's time long. For example, it can be passed directly into the Java call Date.setTime(long time).

If the caller knows the SHA1 of the entire large file being uploaded, Backblaze recommends using large_file_sha1 as the name, and a 40 byte hex string representing the SHA1.

To set the Content-Disposition header provided when the file is downloaded, set 'b2-content-disposition'. (It may be overridden by a value given in the download request.) The value must match the grammar specified in RFC 6266. Parameter continuations are not supported. 'Extended-value's are supported for charset 'UTF-8' (case-insensitive) when the language is empty. Note that this file info will not be included in downloads as a x-bz-info-b2-content-disposition header. Instead, it (or the value specified in a request) will be in the Content-Disposition header.

To set the Content-Language header provided when the file is downloaded, set 'b2-content-language'. The value must match the grammar specified in RFC 2616. Note that this file info will not be included in downloads as a x-bz-info-b2-content-language header. Instead, it (or the value specified in a request) will be in the Content-Language header.

To set the Expires header provided when the file is downloaded, set 'b2-expires'. The value must match the grammar specified in RFC 2616. Note that this file info will not be included in downloads as a x-bz-info-b2-expires header. Instead, it (or the value specified in a request) will be in the Expires header.

To set the Cache-Control header provided when the file is downloaded, set 'b2-cache-control'. The value must match the grammar specified in RFC 2616. Note that this file info will not be included in downloads as a x-bz-info-b2-cache-control header. Instead, it (or the value specified in a request) will be in the Cache-Control header.

To set the Content-Encoding header provided when the file is downloaded, set 'b2-content-encoding'. The value must match the grammar specified in RFC 2616. Note that this file info will not be included in downloads as a x-bz-info-b2-content-encoding header. Instead, it (or the value specified in a request) will be in the Content-Encoding header.

Example: { "src_last_modified_millis" : "1452802803026", "large_file_sha1" : "a3195dc1e7b46a2ff5da4b3c179175b75671e80d", "color": "blue" }

fileRetention

optional

If present, specifies the Object Lock retention settings for the file. Setting the value requires the writeFileRetentions capability and that the bucket is Object Lock-enabled. See Object Lock for details.

legalHold

optional

If present, specifies the Object Lock legal hold status for the file. Setting the value requires the writeFileLegalHolds capability and that the bucket is Object Lock-enabled. Object Lock for details.

serverSideEncryption

optional

If present, specifies the parameters for Backblaze B2 to use for encrypting the uploaded data before storing the file using Server-Side Encryption. See Server-Side Encryption for details.

The file name and file info must fit within a 7,000 byte limit. For files that are uploaded with Server-Side Encryption and/or to Object Lock-enabled buckets, the size limit is reduced to 2,048 bytes. See Files for further details about HTTP header size limit.

Response

Response HTTP Status 200

accountId

The account that owns the file.

action

One of "start", "upload", "hide", "folder", or other values added in the future. "upload" means a file that was uploaded to B2 Cloud Storage. "start" means that a large file has been started, but not finished or canceled. "hide" means a file version marking the file as hidden, so that it will not show up in b2_list_file_names. "folder" is used to indicate a virtual folder when listing files.

bucketId

The bucket that the file is in.

contentLength

The number of bytes stored in the file. Only useful when the action is "upload". Always 0 when the action is "start", "hide", or "folder".

contentSha1

The SHA1 of the bytes stored in the file as a 40-digit hex string. Large files do not have SHA1 checksums, and the value is "none". The value is null when the action is "hide" or "folder".

contentMd5

optional

The MD5 of the bytes stored in the file as a 32-digit hex string. Not all files have an MD5 checksum, so this field is optional, and set to null for files that do not have one. Large files do not have MD5 checksums, and the value is null. The value is also null when the action is "hide" or "folder".

contentType

When the action is "upload" or "start", the MIME type of the file, as specified when the file was uploaded. For "hide" action, always "application/x-bz-hide-marker". For "folder" action, always null.

fileId

The unique identifier for this version of this file. Used with b2_get_file_info, b2_download_file_by_id, and b2_delete_file_version. The value is null when for action "folder".

fileInfo

The custom information that was uploaded with the file. This is a JSON object, holding the name/value pairs that were uploaded with the file.

fileName

The name of this file, which can be used with b2_download_file_by_name.

fileRetention

The Object Lock retention settings for this file, if any.
This field is filtered based on application key capabilities; the readFileRetentions capability is required to access the value. See Object Lock for more details on response structure.
This field is omitted when the action is "hide" or "folder".

legalHold

The Object Lock legal hold status for this file, if any.
This field is filtered based on application key capabilities; the readFileLegalHolds capability is required to access the value. See Object Lock for more details on response structure.
This field is omitted when the action is "hide" or "folder".

replicationStatus

The Replication Status for this file, if any. This will show either PENDING, COMPLETED, FAILED, or REPLICA. For details see Cloud Replication
This field is omitted when the file is not part of a replication rule.

serverSideEncryption

When the file is encrypted with Server-Side Encryption, the mode ("SSE-B2" or "SSE-C") and algorithm used to encrypt the data. If the file is not encrypted with Server-Side Encryption, then both mode and algorithm will be null.
This field is omitted when the action is "hide" or "folder".

uploadTimestamp

This is a UTC time when this file was uploaded. It is a base 10 number of milliseconds since midnight, January 1, 1970 UTC. This fits in a 64 bit integer such as the type "long" in the programming language Java. It is intended to be compatible with Java's time long. For example, it can be passed directly into the java call Date.setTime(long time).
Always 0 when the action is "folder".

Response Errors

Unable to start large file. If possible the server will return a JSON error structure. Errors include:

status

code

description

400

bad_bucket_id

The requested bucket ID does not match an existing bucket.

400

bad_request

The request had the wrong fields or illegal values. The message returned with the error will describe the problem.

400

cannot_delete_non_empty_bucket

A bucket must be empty before it can be deleted. To delete this bucket, first remove all of the files in the bucket, then try the delete operation again.

400

custom_timestamp_invalid

The request has an invalid custom upload timestamp.

400

custom_timestamp_not_allowed

The account is not allowed to specify a custom upload timestamp.

401

bad_auth_token

The auth token used is not valid. Call b2_authorize_account again to either get a new one, or an error message describing the problem.

401

expired_auth_token

The auth token used has expired. Call b2_authorize_account again to get a new one.

401

unauthorized

The auth token used is valid, but does not authorize this call with these parameters. The capabilities of an auth token are determined by the application key used with b2_authorize_account.

API Versions

v2: Consistent file structures (Sept 13, 2018)

Now returns action ("start"), contentLength (0), and contentSha1 ("none").

v1: Application keys (July 26, 2018)

Incompatible change: After calling b2_authorize_account with an application key that does not have the right permissions, this call will return a 401 Unauthorized.

v1: Original release (September 22, 2015)

Sample Code

Code

ACCOUNT_AUTHORIZATION_TOKEN=''; # Provided by b2_authorize_account
BUCKET_ID=''; # The ID of bucket you want the file to land in. The bucket ID is provided by b2_create_bucket and b2_list_buckets
FILE_NAME=''; # File name as it will appear on B2
CONTENT_TYPE=''; # Content type of the file. 
curl \
    -H "Authorization: $ACCOUNT_AUTHORIZATION_TOKEN" \
    -d "`printf '{"fileName":"%s", "bucketId":"%s", "contentType":"%s"}' $B2_FILE_NAME $BUCKET_ID $CONTENT_TYPE`" \
    "$API_URL/b2api/v2/b2_start_large_file";

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code

import java.io.*;
import java.util.*;
import javax.json.*;
import java.net.HttpURLConnection;
import java.net.URL;

String apiUrl = ""; // Provided by b2_authorize_account
String bucketId = ""; // The ID of the destination bucket. The bucket ID is provided by b2_create_bucket, b2_list_buckets. 
String fileName = ""; // Name of the file as it will appear in B2
String fileContentType = ""; // Content type of the file
String accountAuthorizationToken = ""l // Provided by b2_authorize_account

// Create a JSON object
JsonObject startLargeFileJsonObj = Json.createObjectBuilder()
        .add("fileName", fileName)
        .add("contentType", fileContentType)
        .add("bucketId", bucketId)
        .build();

// Convert the JSON object to a string
StringWriter sw = new StringWriter();
JsonWriter jw = Json.createWriter(sw);
jw.writeObject(startLargeFileJsonObj);
jw.close();
String postData = sw.toString();

// Send it over the wire
try {
    URL url = new URL(apiUrl + "/b2api/v2/b2_start_large_file");
    connection = (HttpURLConnection)url.openConnection();
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Authorization", accountAuthorizationToken);
    connection.setRequestProperty("Content-Type", "application/json");
    connection.setRequestProperty("Charset", "UTF-8");
    connection.setRequestProperty("Content-Length", Integer.toString(postData.length()));
    connection.setDoOutput(true);
    DataOutputStream dataOutputStream = new DataOutputStream(connection.getOutputStream());
    dataOutputStream.writeBytes(postData);
	String jsonResponse = myInputStreamReader(connection.getInputStream());
	System.out.println(jsonResponse);   
} catch (Exception e) {
    e.printStackTrace();
} finally {
    connection.disconnect();
}

// Input stream reader example. 
static public String myInputStreamReader(InputStream in) throws IOException {
    InputStreamReader reader = new InputStreamReader(in);
    StringBuilder sb = new StringBuilder();
    int c = reader.read();
    while (c != -1) {
        sb.append((char)c);
        c = reader.read();
    }
    reader.close();
    return sb.toString();
}

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code

import base64
import json
import urllib2

file_name = "" # Name of the file as it appears in B2
content_type = "" # Content Type of the file
bucket_id = "" # The ID of the bucket provided by b2_create_bucket or b2_list_buckets
request = urllib2.Request(
    '%s/b2api/v2/b2_start_large_file' % api_url,
    json.dumps({ 'fileName': file_name, 'contentType': content_type, 'bucketId': bucket_id }),
    headers = { 'Authorization': account_authorization_token }
)
response = urllib2.urlopen(request)
response_data = json.loads(response.read())
response.close() 

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code


import Foundation

let apiUrl = "" // Provided by b2_authorize_account
let fileName = "" // The file name of the file to upload
let accountAuthorizationToken = "" // Provided by b2_authorize_account
let bucketId = "" // Provided by b2_create_bucket, b2_list_buckets
let contentType = "" // The content type of the file. See b2_start_large_file documentation for more information.

// Create the request
let requestBody: [String:Any] = ["fileName":fileName, "bucketId":bucketId, "contentType":contentType];
var request = URLRequest(url: URL(string: "\(apiUrl)/b2api/v2/b2_start_large_file")!)
request.httpMethod = "POST"
request.addValue(accountAuthorizationToken, forHTTPHeaderField: "Authorization")
do {
	request.httpBody = try JSONSerialization.data(withJSONObject: requestBody, options: .prettyPrinted)
} catch let error as NSError {
	print(error.localizedDescription)
}

// Create the task
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
	if let jsonData = data {
		let json = String(data: jsonData, encoding: .utf8)
		print("\(json!)")
	}
}

// Start the task
task.resume()

// Swift 4.1 (swiftlang-902.0.48 clang-902.0.37.1) Xcode 9.3.1 (9E501)

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code

require 'json'
require 'net/http'

bucket_id = "" # Provided by b2_create_bucket, b2_list_buckets
file_name = "" # File to be uploaded
content_type = "" # The content type of the file. See b2_start_large_file documentation for more information.
account_authorization_token = "" # Provided by b2_authorize_account
uri = URI.join("#{api_url}/b2api/v2/b2_start_large_file")
req = Net::HTTP::Post.new(uri)
req.add_field("Authorization","#{account_authorization_token}")
req.body = "{\"bucketId\":\"#{bucket_id}\",\"fileName\":\"#{file_name}\",\"contentType\":\"#{content_type}\"}"
http = Net::HTTP.new(req.uri.host, req.uri.port)
http.use_ssl = true
res = http.start {|http| http.request(req)}
case res
when Net::HTTPSuccess then
    res.body
when Net::HTTPRedirection then
    fetch(res['location'], limit - 1)
else
    res.error!
end

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code

using System;
using System.Net;
using System.Text;
using System.IO;

String bucketId = ""; // Provided by b2_create_bucket or b2_list_buckets
String fileName = ""; // Name of the file as it will appear in B2
String contentType = ""; // Content type of the file
String apiUrl = ""; // Provided by b2_authorize_account
String authorizationToken = ""; // Provided by b2_authorize_account

// Setup JSON to post.
String startLargeFileJsonStr = "{\"bucketId\":\"" + bucketId + "\",\"fileName\":\"" + fileName + "\",\"contentType\":\"" + contentType + "\"}";
byte[] jsonData = Encoding.UTF8.GetBytes(startLargeFileJsonStr);

// Send over the wire
HttpWebRequest startLargeFileRequest = (HttpWebRequest)WebRequest.Create(apiUrl + "/b2api/v2/b2_start_large_file");
startLargeFileRequest.Method = "POST";
startLargeFileRequest.Headers.Add("Authorization", authorizationToken);
startLargeFileRequest.ContentType = "application/json; charset=utf-8";
startLargeFileRequest.ContentLength = jsonData.Length;
using (Stream stream = startLargeFileRequest.GetRequestStream())
{
    stream.Write(jsonData, 0, jsonData.Length);
    stream.Close();
}

// Handle the response and print the json
try
{
    HttpWebResponse startLargeFileResponse = (HttpWebResponse)startLargeFileRequest.GetResponse();
    using(StringReader responseReader = new StreamReader(startLargeFileResponse.GetResponseStream()))
    {
    	String json = responseReader.ReadToEnd();
    	Console.WriteLine(json);
    }
    startLargeFileResponse.Close();
}
catch (WebException e)
{
    using (HttpWebResponse errorResponse = (HttpWebResponse)e.Response)
    {
        Console.WriteLine("Error code: {0}", errorResponse.StatusCode);
        using (StreamReader reader = new StreamReader(errorResponse.GetResponseStream()))
        {
            String text = reader.ReadToEnd();
            Console.WriteLine(text);
        }
    }
}

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}

Code

<?php

$file_name = ""; // File to be uploaded
$bucket_id = ""; // Provided by b2_create_bucket, b2_list_buckets
$content_type = ""; // The content type of the file. See b2_start_large_file documentation for more information.
// Construct the JSON to post
$data = array("fileName" => $file_name, "bucketId" => $bucket_id, "contentType" => $content_type);
$post_fields = json_encode($data);

// Setup headers
$headers = array();
$headers[] = "Accept: application/json";
$headers[] = "Authorization: " . $account_auth_token;

// Setup curl to do the post
$session = curl_init($api_url . "/b2api/v2/b2_start_large_file");
curl_setopt($session, CURLOPT_HTTPHEADER, $headers);  // Add headers
curl_setopt($session, CURLOPT_POSTFIELDS, $post_fields); 
curl_setopt($session, CURLOPT_RETURNTRANSFER, true); // Receive server response
// Post the data
$server_output = curl_exec($session);
curl_close ($session);
print $server_output;

?>

Output

{
  "accountId": "ACCOUNT_ID",
  "action": "start",
  "bucketId": "b2f6f21365e1d29f6c580f18",
  "contentLength": 0,
  "contentSha1": "none",
  "contentType": "application/zip",
  "fileId": "4_zb2f6f21365e1d29f6c580f18_f20150c1fda5f4c8d_d20180919_m215912_c002_v0001110_t0050",
  "fileInfo": {},
  "fileName": "~/Downloads/512MB.zip",
  "fileRetention": {
    "isClientAuthorizedToRead": true,
    "value": {
      "mode": null,
      "retainUntilTimestamp": null
    }
  },
  "legalHold": {
    "isClientAuthorizedToRead": true,
    "value": null
  },
  "serverSideEncryption": {
    "algorithm": null,
    "mode": null
  },
  "uploadTimestamp": 1537394352000
}