IMS Public Draft

# Result JSON Binding
in the `application/vnd.ims.lis.v2.result+json` format

Public Draft - Content-Item Message

Media Type | application/vnd.ims.lis.v2.result+json
RDF Type | http://purl.imsglobal.org/vocab/lis/v2/outcomes#Result
JSON-LD | http://purl.imsglobal.org/ctx/lis/v2/Result

Date Issued: 7 April 2014
Latest version: http://www.imsglobal.org/lti

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v1.0 Public Draft - Revision: 7 April 2014

## Abstract

This specification defines a minimal representation of an LIS Result object which merely provides a single score as a decimal value in the range [0, 1].

## Table of Contents

## 1. Introduction

This specification defines a minimal representation of an LIS Result object which merely provides a single score as a decimal value in the range [0, 1].

Figure 1 shows the representation of a Result resource in the `application/vnd.ims.lis.v2.result+json` format.

    {
      "@context" : "http://purl.imsglobal.org/ctx/lis/v2/Result",
      "@type" : "Result",
      "resultScore" : 0.83,
      "comment" : "This is exceptional work."
    }

Figure 1. Example JSON document containing a Result object

### 1.1 How To Read this Document

This specification defines the structure of a JSON document using a graphical notation. In this notatation, an object is represented by a box that branches out to other boxes corresponding to the properties of that object, as shown in Figure 2.

Figure 2. Representation of a JSON object

Figure 2 is not a complete representation of a `Result` object because there are embedded objects (`resultPerson`, `comment`, `resultOf`). A complete diagram would show branches emanating from the embedded objects to reveal their properties, and so on, recursively. For a complete representation, see Figure 6 below.

Each box representing a property specifies the name and type of the property , as shown in Figure 3.

Figure 3. Graphical notation for a property

If a property is optional, its box will be decorated with a circle that contains a question mark, as shown in Figure 3.

If a property can have multiple values, then its box in the graphical notation is decorated with a circle that contains a plus sign (+) as shown in Figure 4. In this example, the `result` property may reference more than one `Result` object. Ordinarily, these values are encapsulated within a JSON array, but if it turns out that only one value is present, then the square brackets for the array are optional.

Figure 4. Example of a repeatable property

An object within a JSON-LD document may have one of four possible representations:

1. The object may be identified by a fully-qualified URI reference.
2. The object may be identified by a Compact URI reference, known as a CURIE [CURIE-syntax], that can be expanded to a fully qualified URI
3. The object may be identified by a simple name that is mapped to a fully-qualified URI. This mapping is defined by the JSON-LD context.
4. The object may be embedded within the document.

When an object or enumerable value is to be identified by a simple name, the box representing the corresponding property will be decorated with the #sn hash tag, as shown in Figure 5.

Figure 5. Property whose value is a simple name reference for an individual object or enumerable value

### 1.2 Reserved Terms

The JSON-LD standard reserves a handful of property names and tokens that have special meaning. These names and tokens, described below, begin with the '@' symbol.

@context
  Used to reference (by URI or by value) a context which declares the simple names that appear throughout a JSON document.
@id
  Used to uniquely identify things that are being described in the JSON document. The value of an @id property is either a fully-qualified URI, a CURIE, or a simple name that expands to a fully-qualified URI by virtue of the rules defined in the JSON-LD Context.

  The @id property may identify a so-called blank node by using a CURIE with an underscore as the prefix. The binding of a JSON-LD document MAY include identifiers for blank nodes, but these identifiers are not required.

@type
  Used to set the data type of an object or property value.

JSON-LD specifies four other reserved terms (@value, @language, @container, @list). Ordinarily, these terms are not used in the JSON binding for `Result` objects. However, implementations that extend this specification by including additional properties may utilize these reserved terms in accordance with the rules defined by [JSON-LD-syntax].

### 1.3 The JSON-LD Context

In JSON-LD, a context is used to map simple names that appear in a JSON document to URI values for properties or data types in a formal vocabulary (typically an RDF ontology). For example, the standard context [LIS-v2-Result] for a Result contains the following rewrite rules (among others):

      {
        "@context" = {
          "liso" : "http://purl.imsglobal.org/vocab/lis/v2/outcomes#",
          "resultPerson" : "liso:resultPerson",
          ...
        }
      }

## 2. The Result Media Type

The following list defines the necessary and sufficient conditions for a document to conform to the `application/vnd.ims.lis.v2.result+json` media type.

1. The document MUST be a valid JSON document, in accordance with [RFC4627].
2. The document MUST contain either a single top-level JSON object, or an array of top-level JSON objects. The first object encountered (either the single top-level object or the first element of the array) is called the root object.
3. The root object must have a `@type` property whose value is "`Result`".
4. Every top-level object MUST have a `@context` property that references one or more JSON-LD contexts (either by URI or by value).
5. Collectively, the set of contexts imported by the root object MUST contain all of the terms found in the standard context [LIS-v2-Result]. In particular, the set of imported contexts must contain all the simple names that appear in the standard context, and those simple names must resolve to the same values that appear in the standard context. This requirement may be satisfied by ensuring that the root object imports the standard context explicitly, or by importing a collection of other contexts that contain equivalent terms.
6. The set of contexts imported by the root object MAY include additional terms that do not appear in the standard context [LIS-v2-Result].
7. Duplicate mappings for names among the imported contexts MUST be overwritten on a last-defined-overrides basis.
8. If the JSON-LD context coerces a property to a URI reference, then values of that property MUST be expressed as a fully-qualified URI reference, or a CURIE or a simple name declared by the context.
9. A collection property is any property whose maximum cardinality is greater than 1. Except for the `@context` property, a non-empty collection MUST always be represented as a JSON array whose values are enclosed in square brackets. Whereas, in general, the JSON-LD syntax specification allows a collection containing a single value to omit the square brackets, the `application/vnd.ims.lis.v2.result+json` media type requires square brackets for all non-empty collections other than the `@context` property.
10. An empty collection property may be represented either by an empty array (i.e. square brackets containing no elements), or by omitting the property altogether.
11. Like all other properties, the `@id` property of a given object is mandatory if the minimum cardinality of that property, as defined by this specification, is greater than zero. The `@id` property is optional for all other objects (even if it is not explicitly listed in the set of properties for an object). Conforming implementations SHOULD include the `@id` property for all addressable objects.
12. If the `@id` property is mandatory, then the value MUST NOT treat the object as a blank node. In this case, the `@id` value MUST NOT be a CURIE with an underscore as the prefix.
13. Every top-level object MUST contain a `@type` property and a @context property.
14. An embedded object MUST contain a `@type` property if the object value is a subtype of the declared range of the property.
15. Values for properties named in the standard context [LIS-v2-Result], MUST not utilize the String Internationalization or Typed Value syntax as described in [JSON-LD-syntax].
16. If the context does not coerce the value of an object property to a URI reference, then the object must be rendered as an embedded object.
17. The properties of embedded objects must respect the cardinality constraints specified in the section titled JSON Data Bindings.

## 3. JSON Data Bindings

Figure 6 presents a complete graphical representation of the JSON binding for a Result object. The subsections following this figure provide details about each object that appears in the JSON binding for a Result object.

Figure 6. Complete JSON representation of Result

### 3.1 Activity

A resource that a person may experience such as a video or an assessment. This entity represents the resource itself, not the person's engagement with the resource.
Figure 7. Activity

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `Activity` instance. | xs:anyURI
activityTemplate | 0..1 |  | Activity

Table 1. Activity properties

### 3.2 Context

A learning context, such as a Course Section.
Figure 8. Context

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `Context` instance. | xs:anyURI
id | 1 |  | xs:normalizedString
lineItem | * | A LineItem that records results for some learning activity within this context. | LineItem
lineItems | 0..1 | Read Only. The container that holds the collection of LineItem resources for this Context. In general, this container is optional. However, if the Context has any associated LineItems, then the container is required. As a best practice, implementations every Context should expose a LineItemContainer to clients, even if it is empty. | LineItemContainer
sourcedId | 0..1 |  | xs:normalizedString

Table 2. Context properties

### 3.3 DataValue.Type

Figure 9. DataValue.Type

### 3.4 LineItem

Figure 10. LineItem

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `LineItem` instance. | xs:anyURI
assignedActivity | 0..1 | The Activity that learners engage with to produce the Results recorded in this LineItem. | Activity
label | 0..1 | A human-friendly label for this LineItem suitable for display. For example, this label might be used as the heading of a column in a gradebook. | Literal
lineItemOf | 1 | The context to which this LineItem belongs. | Context
reportingMethod | 1 | Identifies the property that is reported as the `resultScore` of the Results within this LineItem. | Property
result | * | A Result associated with this LineItem. | Result
results | 1 | Read Only. The container holding the Results for this LineItem. | ResultContainer
scoreConstraints | 0..1 | Constraints on the scores recorded in the Results associated with this LineItem. | NumericLimits

Table 3. LineItem properties

### 3.5 LineItemContainer

A container that holds a collection of LineItem resources.
Figure 11. LineItemContainer

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `LineItemContainer` instance. | xs:anyURI
membershipPredicate | 0..1 | Indicates which predicate of the container's subject should be used to determine membership in the container. | Property
membershipSubject | 0..1 | Indicates which resource is the subject for the members of the container. | Context

Table 4. LineItemContainer properties

### 3.6 NumericLimits

Defines the maximum values for numerical scores.
Figure 12. NumericLimits

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `NumericLimits` instance. | xs:anyURI
extraCreditMaximum | 0..1 | The maximum number of extra credit points that a learner may earn. | xs:float
normalMaximum | 0..1 | The maximum number of points that a learner may earn without extra credit. | xs:float
totalMaximum | 0..1 | The maximum number of points that a learner may earn. This value is given by
        totalMaximum = normalMaximum + extraCreditMaximum
| xs:float

Table 5. NumericLimits properties

### 3.7 Person

A container for all the information about a single person.
Figure 13. Person

### 3.8 Property

Figure 14. Property

### 3.9 Result

A container that holds the result of some scorable activity or assignment.

    {
      "@context" : "http://purl.imsglobal.org/ctx/lis/v2/Result",
      "@type" : "Result",
      "resultScore" : 0.83,
      "comment" : "This is exceptional work."
    }

Figure 15. Result

Property | Mult | Description | Type
--- | --- | --- | ---
@context | 1..* | This value specifies one or more JSON-LD contexts, either by reference or by value. When multiple contexts are specified, they must be encapsulated within an array. For most implementations, the value will be the single URI for the standard context associated with the `application/vnd.ims.lis.v2.result+json` media type. In this case, the value will be `"http://purl.imsglobal.org/ctx/lis/v2/Result"` | JSON-LD Context
@type | 1 | A simple name identifying the object's type. The standard context [LIS-v2-Result] defines the following simple names that are applicable: `Result` Implementations may use a custom JSON-LD context which defines simple names for additional types that are subtypes of `Result.` | owl:Class (Simple Name reference)
@id | 0..1 | The URI that identifies this `Result` instance. | xs:anyURI
resultScore | 0..1 | The final score that should be displayed in a gradebook for this Result object. | Literal
comment | 0..1 | A comment about this Result suitable for display to the learner. Typically, this is a comment made by the instructor or grader. | DataValue.Type
extraCreditScore | 0..1 | The number of exta credit points earned by the learner. | xs:decimal
normalScore | 0..1 | The score earned by the learner before adding extra credit or subtracting penalties. | xs:decimal
penaltyScore | 0..1 | The number of points deducted from the normal score due to some penalty such as submitting an assignment after the due date. | xs:decimal
resultOf | 1 | The LineItem within which this Result is contained. | LineItem
resultPerson | 1 | The person whose score is recorded in this Result. | Person
totalScore | 0..1 | The total score on the assignment given by
        totalScore = normalScore + extraCreditScore - penalty
This value does not take into account the effects of curving. | xs:decimal

Table 6. Result properties

### 3.10 ResultContainer

A container that holds a collection of Result resources.
Figure 16. ResultContainer

Property | Mult | Description | Type
--- | --- | --- | ---
@id | 0..1 | The URI that identifies this `ResultContainer` instance. | xs:anyURI
membershipPredicate | 0..1 | Indicates which predicate of the container's subject should be used to determine membership in the container. | Property
membershipSubject | 0..1 | Indicates which resource is the subject for the members of the container. | LineItem

Table 7. ResultContainer properties

### 3.11 ScoreConstraints

The abstract base class for all the various kinds of constraints that might be imposed on the Results associated with a LineItem.
Figure 17. ScoreConstraints
Direct Known Subtypes:
NumericLimits

### 3.12 Literal

Restriction Base | http://www.w3.org/2001/XMLSchema#string

Table 8. Facets of Literal

## 4. References

[CURIE-syntax]
  Mark Birbeck, Shane McCarron. CURIE Syntax 1.0. W3C Working Group Note. 16 December 2010.
[JSON-LD-syntax]
  Manu Sporny, Dave Longley, Gregg Kellogg, Markus Lanthaler, Mark Birbeck. Json-LD Syntax 1.0. 12 July 2012. W3C Working Draft.
[RFC4627]
  D. Crockford. The application/json Media Type for JavaScript Object Notation (JSON). Internet RFC 4627. July 2006.

## About this Document

Title: | Result JSON Binding in the `application/vnd.ims.lis.v2.result+json` format
Editor: | Stephen Vickers (IMS Global)
Version: | 1.0
Version Date: | 7 April 2014
Release: | Public Draft
Status: | IMS Public Draft
Purpose: | This document is made available for review and comment by the public community at large.
Document Location: | Join the discussion and post comments on the LTI Public Forum: http://www.imsglobal.org/community/forum/categories.cfm?catid=44

### List of Contributors

The following list of individuals contributed to the authoring of this document:

Viktor Haag | Desire2Learn | Bracken Mosbacker | Instructure
Brad Humphrey | Instructure | Claude Vervoort | Cengage
Greg McFall | Pearson | Stephen Vickers | IMS Global Learning Consortium

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The Specification is at all times subject to change and revision without notice.

It is your sole responsibility to evaluate the usefulness, accuracy, and completeness of the Specification as it relates to you.

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Please contact IMS Global through our website at http://www.imsglobal.org

Please refer to Document Name: IMS Global Learning Tools Interoperability - Content-Item Message Public Draft v1.0
Revision: 7 April 2014