DropboxSDK

A Julia package to access Dropbox via its API. This package can either be used as library for other packages, or as command line client dbftp.

You install this package in the usual way via

using Pkg
Pkg.add("DropboxSDK")

Before you can using this package to access your Dropbox account, you need to obtain an authorization token. This is essentially a password that allows an application to access your Dropbox account on your behalf.

Note: A token is like a password; treat it accordingly -- make sure it never ends up in a repository, on a command line, in log file, etc.

To obtain an authorization token, go to this page and follow the instructions there. You can call the app e.g. Julia SDK. You have the option to "sandbox" the token by restricting it to an app-specific subdirectory. This is a good idea for testing.

Save the token into a file .dropboxsdk.http in your home directory. The file should look like

access_token:xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

where the xxx are replaced by the authorization token that looks like a random string of letters and numbers.

Make sure the file is owned by you, and that no one else can read it (chmod go-rwx ~/.dropboxsdk.http). As a security precaution, DropboxSDK will refuse to read the file otherwise.

julia bin/dbftp.jl help

The command line client works similar to sftp. (There is no REPL yet.) These commands are implemented:

• account: Display account information
• cmp: Compare local and remote files (compare content hashes)
• du: Display space usage
• get: Download files
• help: Get help
• ls: List files
• mkdir: Create directory
• put: Upload files
• rm: Delete file or directory
• version: Show version number

Note that rm can delete non-empty directories. This is a convenient way to delete large numbers of files in a very short time. Deleted files can be restored (using e.g. the Dropbox web interface) for some weeks or months.

using DropboxSDK

These API functions are currently supported; see their respective documentation:

• files_create_folder: Create a directory
• files_delete: Delete a file or directory (recursively)
• files_download: Get a file
• files_get_metadata: Get metadata (size etc.) for a file or directory
• files_list_folder: List directory content
• files_upload: Upload one or more files
• users_get_current_account: Get information about the current account
• users_get_space_usage: Get used and available space

There are also a few local helper functions:

• calc_content_hash: Calculate content hash (fingerprint) of a local file
• get_authorization: Read credentials from a configuration file

The command line interface and the test cases also contain good pointers for how to use this API.

Given how the Dropbox API is designed, it seems that Dropbox considers metadata write operations to be particularly expensive. (These are operations that modify how a directory looks.) Metadata write operations are thus strongly rate limited.

For example, running two instances of dbftp simultaneously will almost certainly result in temporary errors and retries. (DropboxSDK detects temporary errors, and retries automatically. However, this still slows things down.) Dropbox offers special functions to e.g. upload many files simultaneously. DropboxSDK uses these, although not yet in parallel.

Conversely, metadata read operations (e.g. reading a directory or downloading a file) seem efficient, and these operations can presumably run in parallel.