Data

Overview

DiMe is centered around loggers uploading events, represented by the Event class and its subclasses. For example an event could be:

• the user has looked at a PDF document
• the user's pulse is so-and-so

Some events contain linked objects, such as the document that was looked at. These objects, which can appear in several events, e.g. when the user closes the same document are represented by the InformationElement class and its subclasses.

The image below illustrates several events being uploaded over time. Some refer to information elements, many events may naturally refer to the same information element, e.g. opening and closing the same document.

The DiMe data model is implemented as a set of Java classes in the source directory: src/main/java/fi/hiit/dime/data. You can also view the class hierarchy from the javadoc page (requires a HIIT username that is member of the reknow group).

Concrete events

The actual event uploaded to DiMe needs to be one of the concrete subclasses of the Event class, which represent different types of events. To see the full list of currently implemented events check the javadoc page. New classes can be added as needed.

An event is uploaded to DiMe encoded as JSON using the uploading API.

Example

Below is an example of a DesktopEvent with its corresponding Document. This example represents a user having accessed a web page, i.e. the document is the web page in this case, and the event specifies when the web page was accessed.

The example is given below in JSON, which is the data format used for uploading to and downloading from DiMe. The fields and their meaning are explained below in the comments.

{
    // this corresponds to the Java event class
    "@type": "DesktopEvent",	
    // the program that produced the event, here the web browser
    "actor": "Firefox", 
	// a unique id, if left empty DiMe will generate a random id
	"id": "f9654c54d7f38acfe179b04de8c0554ea1d6481b", 
	// typically the host name of the computer where the event was generated
	"origin": "hp8x-15.cs.helsinki.fi", 
	// time stamp when the event was started
	"start": "2015-08-11T12:56:53Z", 
	// type using the Semantic Desktop ontology
	"type": "http://www.semanticdesktop.org/ontologies/2010/01/25/nuao#UsageEvent"
	// the contained InformationElement
	"targettedResource": {
	    // the Java class
	    "@type": "Document", 
		// a unique id, if left empty DiMe will generate a random id
		"id": "d74fa5afb9c04e148fc75a640348f8648c17812b",  
		// 
		"isStoredAs": "http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#RemoteDataObject",
		// mime type, optional
		"mimeType": "text/html", 
		// the plain text, used for search
		"plainTextContent": "The revolution has begun...", 
		// title of the document
		"title": "Revolution of Knowledge Work | Revolution of Knowledge Work", 
		// type using the Semantic Desktop ontology
		"type": "http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#Document", 
		// the URI of the web page or document
		"uri": "http://www.reknow.fi/" 
    },
}

Adding data classes

If you need a new data class, it should be implemented as subclass of the existing ones - please discuss it first e.g. in

• the #dime channel on Slack, or
• open an issue in the issue tracker, or
• send an email to [email protected].