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HTRC Data Capsules are secure computing environments developed to facilitate non-consumptive text analysis research. Each Capsule is a virtual machine (VM) that provides researchers a desktop they can use to perform their investigation of volumes in the HathiTrust Digital Library. 

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titleUse a Capsule

HTRC Data Capsule Configurations

Capsule Technical Specifications

Configuration options:

  • Data Capsule Image: there are two images (versions) of the standard Capsule desktop, one that comes pre-loaded with sample volumes from the HathiTrust and one that does not
  • Virtual Machine CPUs (VCPUs): the number of virtual machine processors from 2-4 VCPUs for the Capsule
  • Memory: between 4GB and 16GB

Pre-installed Software, Libraries, and Data

Each Capsule comes pre-loaded with the following software, libraries, and data. For more information, consult the ReadMe file on the desktop of your Capsule for more details about installed packages.




Anaconda 3 4.2.0 both Python 2.X and 3.X. See list below for the Python libraries pre-installed (some via Anaconda)




InPho Topic Explorer










Voyant Tools

Python Libraries 


  • htrc-feature-reader
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    titleLearn more

  • htrc workset toolkit
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    titleLearn more
    urlHTRC Workset Toolkit


  • csvkit
  • dask
  • GenSim (currently running with warning)
  • nltk
  • numpy
  • pandas
  • pytables
  • regex
  • scipy
  • theano
  • toolz
  • ujson

Sample data

  • 3 sample HTRC worksets of 1000 volumes each: U.S. Government Documents, German language volumes, 19th Century English Literature. 

 User Quotas

There is an overall disk quota, a memory quota, and a CPU quota for each user in the Data Capsule environment. One user can consume up to 100 GB of disk space, ~20 GB of memory, and 10 CPUs. If you attempt to create a second or third Capsule that exceeds your quota in one of the areas above, then you will encounter an error. 

recall policy
recall policy
Capsule Recall Practices

The HTRC Data Capsule service’s maximum capacity flexes depending on the size of the Capsules it hosts. In the event that the Data Capsule service cannot satisfy all simultaneous demands for Capsules:

  • A Capsule may be recalled (i.e. deleted) and the work environment will no longer exist.

    • Capsules will be identified for recall based on criteria such as date of last use and an individual’s resource usage, with the goal being to extend the number of individuals afforded the opportunity to conduct research using a Capsule

    • A researcher whose Capsule is identified for recall will be notified via email regarding the pending recall, and they will have 5 days to respond to the recall notification.

  • Priority in satisfying a new request for a Capsule will be given to researchers whose affiliated organization is a HathiTrust member.

    • At times when the Data Capsule service has reached capacity, incoming requests for Capsules will be screened based on institutional affiliation.

  • Instructors who intend to use the HTRC Data Capsules in a course should contact so that proper arrangements can be made.

  • Users who do not abide by the Terms of Use will have their Capsule recalled immediately.

Using an HTRC Data Capsule

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urlHTRC Data Capsule Step-by-Step Guides

Administering a Capsule

Use the HTRC site to handle administrative tasks for your Capsule:

  • Create - a Capsule is created, but it is not yet running

  • Start - turn the Capsule on in maintenance mode

  • Stop - shutdown a Capsule

  • Delete - the Capsule is deleted (including its data and settings) 

  • Switch modes - change the Capsule from maintenance to secure mode, or vice-versa (see below)

  • See status - view your Capsules and their statuses

  • Interact - use your Capsule either through a desktop view or a terminal (command line) view

Maintenance vs. Secure Mode

The Capsules are configured with special security settings that allow you to interact with them in two modes:  maintenance mode and secure mode

  • In maintenance mode, you are allowed to access the network freely and install whatever software you want. 
  • In secure mode, general network access is restricted, but you can access the HTRC corpus repository, which is otherwise blocked. Any changes you make to the Capsule in secure mode will not persist. To save data from your analysis, you'll need to save your results in the secure volume storage on your Capsule. This storage option is not visible in maintenance mode. 

Interacting with a Capsule

Access your Capsule in-browser from HTRC Analytics either by viewing the Remote Desktop (both modes available) or the Terminal command line interface (Maintenance Mode only). Earlier versions of the Capsule environment required a VNC viewer and passwords for both the VNC and the Capsule's operating system; those requirements are removed in the web-based version that was implemented in August, 2018. You can also SSH into your Capsule in Maintenance Mode only if you've followed the directions under "Advanced Features" to set-up a public key. 

To operate your Capsule, click on the Capsule ID from the Capsule list page. Then choose to either view the remote desktop or the terminal. The terminal will work in Maintenance Mode only. 

If you've established a key for SSH access, you can also SSH into your Capsule when it's in Maintenance Mode by using the command viewable under "Advanced Features" on an individual Capsule's status page.

Importing data to a Capsule

Use the HTRC Workset Toolkit to import HathiTrust text data into your Capsule. Any outside data you plan to analyze in conjunction with HathiTrust data can be added to your Capsule from a web-accessible location when your machine is in Maintenance Mode.

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titleLearn more
urlHTRC Workset Toolkit


Earlier versions of the Capsule environment required passwords for both the VNC and the Capsule's operating system; those requirements are removed in the web-based version that was implemented in August, 2018. If you use the included HTRC Workset Toolkit when in your Capsule to import data to your Capsule, you will be prompted for your HTRC Analytics username and password.

Generic Research Workflow

  1. Create and start a Capsule in the HTRC

  2. View your Capsule using the Remote Desktop view or Terminal view.

  3. Configure the software environment of the Capsule as needed. Download the scripts or programs you plan to use in your analysis

  4. Switch Capsule to secure mode through HTRC

  5. Run your against the secure HTRC corpus repository

  6. Move your results to the secure volume storage on the Capsule

  7. Switch Capsule back to maintenance mode to regain normal network access

Non-consumptive Exports from an HTRC Data Capsule

Data and tools can easily enter a user's Capsule, but anything leaving a Capsule must undergo review prior to release to the user. The guidelines used during review of the outputs of a Capsule are as follows:

  • Files containing any OCR text or images of pages or volumes will be prohibited from leaving a Capsule.  
  • Binary files are prohibited from leaving a Capsule
  • Encrypted files are prohibited from leaving a Capsule
  • PDF files or other format of file that contains images of OCR text or text images are prohibited from leaving a Capsule
  • For any Capsule results directory that exceeds 1 MB in total, the collection will not be released pending discussion with the Capsule owner

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titleRead the policy

A release request must be under 67 MB, and any submitted requests over this size will fail due to technical limitations.

Release requests should include a README text file describing the files included in the request and their data structure.