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About EVT

EVT (Edition Visualization Technology) is a light-weight, open source tool specifically designed to create digital editions from texts encoded according to the TEI XML schemas and Guidelines, freeing the scholars from the burden of web programming and enabling the final users to browse, explore and study digital editions by means of a user-friendly interface.

This tool was born in the context of the Digital Vercelli Book project, in order to allow the creation of a digital edition (which has been available in beta form for more than two years) of the Vercelli Book, a parchment codex of the late tenth century, now preserved in the Archivio e Biblioteca Capitolare of Vercelli and regarded as one of the four most important manuscripts of the Anglo-Saxon period as it regards the transmission of poetic texts in the Old English language. However it has evolved into a tool suitable to fit different texts and needs. For example, it is now being used to publish the digital edition of the Codice Pelavicino manuscript, a medieval codex preserving charters dating back to the XIII century. The continuous development and need to adapt it to different types of documents and TEI-encoded texts has shifted the development focus towards the creation of a more general tool for the web publication of TEI-based digital editions, able to cater for multiple use cases.

The entire structure of the software has been remodeled, in order to make it lighter, more usable and more adaptable; we decided to use the Model View Controller (MVC) approach, which is a very common architectural pattern in object-oriented programming since it allows to separate the logical presentation of the data from the application logic and the processing core. Wanting to maintain the original feature set of EVT, and therefore do not give up the client only approach, we decided to use Angular, a JavaScript framework inspired by the MVC programming logic, especially suitable for the development of client-side Web applications; among other things, this framework allows to define custom HTML components and use the data-binding mechanism to associate the model of the data to the UI elements, and manage the updates of the latter avoiding the direct DOM manipulation.

How it works

Before the refactoring, EVT was composed of two main units: EVT Builder, for the transformation of the encoded text using special XSLT 2.0 templates, and EVT Viewer, for the visualization of the transformation results in a browser and for the user interaction with them. The idea under the new version of EVT is instead to leave to EVT Viewer the task of reading and parsing the encoded text by means of JavaScript functions, and “save” as much as possible within a data model, that persists in the client main memory, and is organized in a way that allows a very quick access to the data in case of need. This has obviously led to the elimination of the EVT Builder phase, and therefore it allows to open a digital edition directly in the browser without any previous XSLT transformation.

Main features

At the present moment, EVT is getting near to a first alpha release. For a complete list of features, please refer to the AngularJS version, but also keep in mind that several new features are envisioned for the first stable release (see There and back again: what to expect in the next EVT version. In order to stay updated on the progress of current EVT 3 developments, you can refer to the CHANGELOG.md file on the develop branch. As soon as a first alpha version is published, the version in the master branch will correspond to the features integrated in the released package.