Dropbox

**Description**
Dropbox is an internet directory synchronization utility which is designed to work on Linux, Mac OS X, and Windows operating systems. Its primary function is to maintain synchronization of a unique hierarchal repository of files which is instantiated across multiple computers. It also provides web access and version control.

__Synchronization__ Dropbox’s primary feature is synchronization, automatically updating a special folder with changes on any number of Internet-connected computers in response to changes in the equivalent folder on any other computer attached to the same account.

__Version Control__ Version control is a process whereby a repository is updated against changes in a file or files, and each or most intermediary steps are preserved. This technology started in the field of software development with the “Source Code Control Program”, written by Marc J. Rochkind (Rochkind) which allowed programmers to make changes to their software code and still have access to all previous versions.

__Web access__ Dropbox has a web interface where all of the files on one’s repository can be accessed through links, displayed in a list format similar to most operating systems’ “list view” modes. The users’ web access portals are protected with unique user names (which are given as the e-mail address given to Dropbox on sign-up) and passwords.

__Public links__ Each Dropbox account includes a “Public Folder” in which every file in a special automatically created folder, regardless of whether it is at the root or is nested in one or a series of subdirectories underneath the root, can be accessed with a unique URL. The operating system’s file view subsystem is slightly modified when Dropbox is installed, allowing the user to obtain the URL and share it on blogs or in e-mails, for example, so that others can access the files by downloading them through the link. The link points to Dropbox’s servers and does not depend on the user’s computer being activated or Internet connected at the time of the remote access. No password or any other security feature is used for the access of these files.

**History**
Dropbox got seed funding in June of 2007 (VentureBeat Profiles), and is currently growing at a rate of 25% month-over-month (Dropbox forums).

**Impact on Teaching and Learning**
Dropbox provides two functions which are particularly useful for education, although any of its features might be as useful in an educational environment as in any other technology-rich context. Specifically, its collaboration and online viewing features provide a virtual nexus for teams of students and a potential point of contact between educators and students. In the Practical Applications section, I list three scenarios where the usefulness of Dropbox is demonstrated in the educational context.

**Practical Applications**
Scenario one: Collaboration in a multi-platform environment

A team of students are tasked with creating a multimedia presentation. There are five students in the group. Two use Windows and two use Macintosh, while the other one uses only Linux. Two of the students are skilled with computers and would be comfortable using a direct network protocol, such as FTP, but the other three students are relatively less skilled with computer networking and would resort to using e-mail and USB sticks to send files to each other, or depend on the other three for expertise. This would waste time and run into limitations such as e-mail attachment size limits. In addition, it would be more complicated for each student to have to remember where to look for files. By applying for a free Dropbox account (2GB as of this writing), and then creating a shared folder between them, files could be copied with no more expertise than normal operating system use. The synchronization would be automatic, and the file limit size is the same as the total space limitation (2GB), and synchronization would proceed between platforms without any further necessary steps. There would be only one place to look for changes.

The specific educational benefits are: Free price is attractive to mostly poor students, no student is required to change platforms to use the service (assuming they are on Macintosh, Windows, or Linux of a fairly recent version), which is relevant in the educational field because students use different platforms. Dropbox’s relative ease-of-use allows students to focus on target expertise rather than learning technology.

Scenario 2: A student writes her dissertation over the course of many months, with a large number of revisions.

Linux, Mac OS X, and Windows currently all use a “replacement” paradigm for dealing with changes to files if the changes occur to a file of the same name. This means that the old file becomes unavailable, and is replaced by the new file. The old file’s location on the physical media is often completely replaced, making restoration impossible. There is some interest in a “log-based” file systems where changes to files are written sequentially, usually after the original file (see Rosenblum, Mendel and Ousterhout). Dropbox provides access to every intermediate version to the first synchronized version using the web interface. In this way, previous versions are not lost, and unwanted changes can be reverted, even if the new version is written over the old version. This is useful for the student writing a large paper, since changes are frequent and often comprehensive, as sections are added, removed, or moved. As a side effect, accidentally deleted files can be recovered using the same process.

The specific educational benefits are: Academic papers and other products are commonly created in an iterative manner, where previous revisions are replaced with newer versions. In clumsy modern OS interface paradigms and on current file systems with no “revision memory”, this often leads to an accidental loss of hours or days of difficult work, as well as a loss of a record of changes which is useful for organization.

Scenario 3: The previous two scenarios are examples, this one really happened. A student creates a video bio of his life centered around cats. The file was very large and needed to be available for a web presentation with other students, with no distracting problems, such as buffering, needing to take several steps to start the video, and so on.

Within each user’s Dropbox folder, there exists another folder called “Public”. Anything in this folder can be accessed with a simple html link. There is no intermediary steps between the link and the data in the file, the link points directly to the contents of the file. The download speed (and to a much lesser extent, the upload speed) are fast and for downloading, can supply enough bandwidth to deliver high-resolution video in real-time.

The specific educational benefits are: Teaching and Learning environments tend to be very scheduled, with limited time for presenting for each student. Technical problems can easily throw schedules off and disrupt the flow of the class. Reliable and fast services are necessary to keep the focus on the learning process and the topic at hand. Publicly sharing information is necessary to present one’s academic work.

**Examples or Demonstrations**
__Synchronization__ To synchronize a file across two computers using Dropbox one must:
 * 1) Sign up for a Dropbox account for one user, or for two users, sign up for two Dropbox accounts.
 * 2) For one user, link both computers to the same Dropbox account, or for two users, link each computer to a different account and create a common shared folder, linking each user’s instantiation of that shared folder to each other.
 * 3) Copy the file, files, directory, or directories into one of the computers (it doesn’t matter which one).
 * 4) The synchronization process itself is automatic. Rebooting the computers will automatically relink them with previous settings to the same account and preserve the shared folders. The time involved in synchronizing the files is mostly a factor of the bandwidth limitations of their Internet connections. For very fast connections, the limits of Dropbox’s servers may become the bottleneck.



__Version Control__ To access a previous version of a file which has been overwritten by a new version, or a different file with the same name and location, one must:
 * 1) Log into the relevant Dropbox account at http://getdropbox.com.
 * 2) Using the file interface under the “Files” tab, navigate the hierarchical directory tree to find the relevant file (see Figure 1).
 * 3) Click the “down arrow” icon at the rightmost end of the relevant file’s file listing
 * 4) Choose “Previous Versions”
 * 5) Choose the desired previous version, which then begins to download.

__Web Access__ To access a file through Dropbox’s web interface, one must:
 * 1) Log into the relevant Dropbox account at http://getdropbox.com.
 * 2) Using the file interface under the “Files” tab, navigate the hierarchal directory tree to find the relevant file (see Figure 1).
 * 3) Click the “down arrow” icon at the rightmost end of the relevant’s file listing.
 * 4) Choose “Download file” which begins a download of the file.

__Public Links__ To make a file in a user’s Dropbox repository available as a publicly-accessible html link, one must:
 * 1) Navigate on the local computer’s file system view using provided file management paradigms, which are slightly different for Mac OS X, and for Windows, and differ slightly by version of the OS as well. In Linux this process is further differentiated by which desktop environment one uses (for example, Gnome or KDE).
 * 2) Move the file to any location within the Public folder, which is automatically created in the Dropbox folder at its root.
 * 3) One can choose at this point to use the web interface or the local operating system to obtain the html link. I will proceed with the web interface as an example.
 * 4) Log into the relevant Dropbox account at http://getdropbox.com
 * 5) Using the file interface under the “Files” tab, navigate the hierarchal directory tree to find the relevant file (see Figure 1).
 * 6) Click the “down arrow” icon at the rightmost end of the relevant’s file listing.
 * 7) Choose “Copy public link” which places an html link to the relevant file into the local operating systems’ clipboard. This can then be “pasted” into any other text field which allows it, such as an e-mail.

__Other Demonstrations__ media type="youtube" key="Bu63Xs0796k" height="344" width="425" align="center" Figure 2: An early video (when Dropbox was in private beta) showing it's main features and operating system interface)

**References**
Dropbox, []

Dropbox forums, ([])

Rochkind, Marc J., (November 1975) - "The Source Code Control System". //IEEE Transactions on software engineering, Vol. SE-1 No. 4.// pp364-370.

Rosenblum, Mendel and Ousterhout, John K. (February 1992) - "[|The Design and Implementation of a Log-Structured File System]". //ACM Transactions on Computer Systems, Vol. 10 Issue 1.// pp26-52.

VentureBeat Profiles, []

**About the Author**
This Wikipage was created by Erik Hill, Masters of Educational Technology Student at the University of Hawaii at Manoa, for ETEC 602, during the Fall 2009 semester.