Появление xAPI (ADL) не было неожиданным событием. Очень продолжительное время велись обсуждения TinCan'а, огромное количество открытых форумов кипели при обсуждении новой спецификации. И только после достаточного обсуждения, ADL выпустила релиз спецификации. Затем, уже после практической работы многих компаний с xApi, появилась CMI5.
И тут появилась аналогичная спецификация IMS Global Learning Consortium под названием Caliper.
Заметное сходство между xAPI и Caliper побудило разработчиков и поставщиков контента прояснить различия в реализации одной или обеих спецификаций (обе из которых в настоящее время нацелены на стандартизацию).
Оба сообщества, поддерживающие xAPI и Caliper, выразили обеспокоенность по поводу возможности экономически эффективной поддержки обеих спецификаций, что привело к запросам как к ADL, так и к IMS о том, возможно ли их согласование.
Вот краткий ответ IMS (http://personeltest.ru/aways/www.imsglobal.org/initial-xapicaliper-comparison)
a) Caliper and xAPI have very different origins. The core xAPI is to enable any type of experience and evidence tracking, both electronic and physical performance and not limited to just web-based courses (as is the case for SCORM). Caliper is the manifestation of the IMS Learning Analytics Framework and the Sensor API and Metric Profile(s) are the first two components of that framework. xAPI and Caliper are NOT equivalent. Adoption should not be one-or-the-other, instead it is a horses-for-courses decision;
b) While both xAPI (Actor/Verb/Object) and Caliper (Actor/Action/Activity) use a data model based upon a triple statement structure there are considerable differences in the detailed structure and usage of the Object and Activity definitions. However, it should be possible for each specification to make use of the others Verb/Action;
Вот краткий ответ ADL (http://personeltest.ru/aways/adlnet.gov/news/2016/07/25/adl-experience-api-and-ims-caliper-discovery-review/)
As xAPI has matured, so too has a similar specification from the IMS Global Learning Consortium called Caliper. There are notable similarities between xAPI and Caliper, which has caused adopters and vendors to clarify implementation differences of one or both specifications (both of which are now targeting standardization). Both communities supporting xAPI and Caliper have expressed concerns about being able to cost-effectively support both specs, which led to inquiries to both ADL Initiative and IMS about whether alignment of the two would be possible.
xAPI (Actor / Verb / Object) и Caliper (Actor / Action / Activity) используют модель данных, основанную на структуре тройного оператора, существуют значительные различия в подробной структуре и использовании определений Object и Activity. Видимо Actor и Verb/Action совпадают, отличаются только Object/Activity?
Я достаточно давно работаю с xAPI, но Caliper мне не был знаком. Пришлось немного изучить документацию (http://personeltest.ru/aways/www.imsglobal.org/sites/default/files/caliper/v1p1/caliper-spec-v1p1/caliper-spec-v1p1.html и www.imsglobal.org/caliper/caliperv1p0/ims-caliper-analytics-implementation-guide)
Скажу сразу, я не нашел значительных лично для меня отличий. То что называется в xAPI statement (Activites) в Caliper называется Event.
Я обратил внимание на наличие так называемой метрики в Caliper, но описание достаточно абстрактное, примеров практического использования мне найти не удалось.
The Caliper information model defines a number of metric profiles, each of which models a learning activity or a supporting activity that helps facilitate learning. A metric profiles raison detre is to encourage vocabulary standardization and re-use among application providers delivering complementary, albeit competing capabilities that collect learning activity data. Each profile provides a domain-specific set of terms and concepts that application designers and developers can draw upon to describe common user interactions in a consistent manner using a shared vocabulary. Annotating a reading, playing a video, taking a test, or grading an assignment submission represent a few examples of the many activities or events that Calipers metric profiles attempt to describe.
Think of each metric profile as a stand-alone, logical container, or collection of one or more Caliper events that together help describe a set of inter-related activities. Each Event type included in a metric profile place constraints on the various entities and actions that can be utilized to describe a learning activity. Vocabulary restrictions are outlined in each profile description under the following headings
На сайте IMS есть очень много красивых картинок, но они еще более усиливают ощущение того, что разница минимальна.
С точки зрения механизма авторизации и хранения (LRS), разницы практически нет, отличие JSON в xApi и JSON-LD в Caliper для меня не существенно. т.е. и в этих вопросах разницы нет.
Давайте посмотрим примеры JSON xApi и Caliper
xApi
{
actor: {
name: Sally Glider,
mbox: mailto:sally@example.com
},
verb: {
id: adlnet.gov/expapi/verbs/completed,
display: { en-US: completed }
},
object: {
id: example.com/activities/hang-gliding-test,
definition: {
type: adlnet.gov/expapi/activities/assessment,
name: { en-US: Hang Gliding Test },
description: {
en-US: The Solo Hang Gliding test, consisting of a timed flight from the peak of Mount Magazine
},
extensions: {
example.com/gliderClubId: test-435
}
}
},
result: {
completion: true,
success: true,
score: {
scaled: 0.95
},
extensions: {
example.com/flight/averagePitch: 0.05
}
},
context: {
instructor: {
name: Irene Instructor,
mbox: mailto:irene@example.com
},
contextActivities:{
parent: { id: example.com/activities/hang-gliding-class-a }
grouping: { id: example.com/activities/hang-gliding-school }
},
extensions: {
example.com/weatherConditions: rainy
}
},
timestamp: 2012-07-05T18:30:32.360Z,
stored: 2012-07-05T18:30:33.540Z,
authority: {
name: Irene Instructor,
mbox: mailto:irene@example.com
}
}
Caliper
{
sensor: example.edu/sensors/1,
sendTime: 2018-11-15T11:05:01.000Z,
dataVersion: purl.imsglobal.org/ctx/caliper/v1p1,
data: [
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: example.edu/users/554433,
type: Person,
dateCreated: 2018-08-01T06:00:00.000Z,
dateModified: 2018-09-02T11:30:00.000Z
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
type: Assessment,
name: Quiz One,
items: [
{
id: example.edu/terms/201801/courses/7/sections/1/assess/1/items/1,
type: AssessmentItem
},
{
id: example.edu/terms/201801/courses/7/sections/1/assess/1/items/2,
type: AssessmentItem
},
{
id: example.edu/terms/201801/courses/7/sections/1/assess/1/items/3,
type: AssessmentItem
}
],
dateCreated: 2018-08-01T06:00:00.000Z,
dateModified: 2018-09-02T11:30:00.000Z,
datePublished: 2018-08-15T09:30:00.000Z,
dateToActivate: 2018-08-16T05:00:00.000Z,
dateToShow: 2018-08-16T05:00:00.000Z,
dateToStartOn: 2018-08-16T05:00:00.000Z,
dateToSubmit: 2018-09-28T11:59:59.000Z,
maxAttempts: 2,
maxScore: 15.0,
maxSubmits: 2,
version: 1.0
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: example.edu,
type: SoftwareApplication,
version: v2
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: example.edu/terms/201801/courses/7/sections/1,
type: CourseSection,
academicSession: Fall 2018,
courseNumber: CPS 435-01,
name: CPS 435 Learning Analytics, Section 01,
category: seminar,
subOrganizationOf: {
id: example.edu/terms/201801/courses/7,
type: CourseOffering,
courseNumber: CPS 435
},
dateCreated: 2018-08-01T06:00:00.000Z
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: urn:uuid:c51570e4-f8ed-4c18-bb3a-dfe51b2cc594,
type: AssessmentEvent,
actor: example.edu/users/554433,
action: Started,
object: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
generated: {
id: example.edu/terms/201801/courses/7/sections/1/assess/1/users/554433/attempts/1,
type: Attempt,
assignee: example.edu/users/554433,
assignable: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
count: 1,
dateCreated: 2018-11-15T10:15:00.000Z,
startedAtTime: 2018-11-15T10:15:00.000Z
},
eventTime: 2018-11-15T10:15:00.000Z,
edApp: example.edu,
group: example.edu/terms/201801/courses/7/sections/1,
membership: {
id: example.edu/terms/201801/courses/7/sections/1/rosters/1,
type: Membership,
member: example.edu/users/554433,
organization: example.edu/terms/201801/courses/7/sections/1,
roles: [ Learner ],
status: Active,
dateCreated: 2018-08-01T06:00:00.000Z
},
session: {
id: example.edu/sessions/1f6442a482de72ea6ad134943812bff564a76259,
type: Session,
startedAtTime: 2018-11-15T10:00:00.000Z
}
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: urn:uuid:dad88464-0c20-4a19-a1ba-ddf2f9c3ff33,
type: AssessmentEvent,
actor: example.edu/users/554433,
action: Submitted,
object: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
generated: {
id: example.edu/terms/201801/courses/7/sections/1/assess/1/users/554433/attempts/1,
type: Attempt,
assignee: example.edu/users/554433,
assignable: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
count: 1,
dateCreated: 2018-11-15T10:15:00.000Z,
startedAtTime: 2018-11-15T10:15:00.000Z,
endedAtTime: 2018-11-15T10:55:12.000Z,
duration: PT40M12S
},
eventTime: 2018-11-15T10:25:30.000Z,
edApp: example.edu,
group: example.edu/terms/201801/courses/7/sections/1,
membership: {
id: example.edu/terms/201801/courses/7/sections/1/rosters/1,
type: Membership,
member: example.edu/users/554433,
organization: example.edu/terms/201801/courses/7/sections/1,
roles: [Learner],
status: Active,
dateCreated: 2018-08-01T06:00:00.000Z
},
session: {
id: example.edu/sessions/1f6442a482de72ea6ad134943812bff564a76259,
type: Session,
startedAtTime: 2018-11-15T10:00:00.000Z
}
},
{
"@context": purl.imsglobal.org/ctx/caliper/v1p1,
id: urn:uuid:a50ca17f-5971-47bb-8fca-4e6e6879001d,
type: GradeEvent,
actor: {
id: example.edu/autograder,
type: SoftwareApplication,
version: v2
},
action: Graded,
object: {
id: example.edu/terms/201801/courses/7/sections/1/assess/1/users/554433/attempts/1,
type: Attempt,
assignee: example.edu/users/554433,
assignable: example.edu/terms/201801/courses/7/sections/1/assess/1?ver=v1p0,
count: 1,
dateCreated: 2018-11-15T10:15:00.000Z,
startedAtTime: 2018-11-15T10:15:00.000Z,
endedAtTime: 2018-11-15T10:55:12.000Z,
duration: PT40M12S
},
eventTime: 2018-11-15T10:57:06.000Z,
edApp: example.edu,
generated: {
id: example.edu/terms/201801/courses/7/sections/1/assess/1/users/554433/attempts/1/scores/1,
type: Score,
attempt: example.edu/terms/201801/courses/7/sections/1/assess/1/users/554433/attempts/1,
maxScore: 15.0,
scoreGiven: 10.0,
scoredBy: example.edu/autograder,
comment: auto-graded exam,
dateCreated: 2018-11-15T10:56:00.000Z
},
group: example.edu/terms/201801/courses/7/sections/1
}
]
}
Должен признать, что я не смог выявить для себя существенную разницу между этими спецификациями.
Фраза
IMS Learning Analytics Framework and the Sensor API and Metric Profile(s) are the first two components of that frameworkговорит о том, что видимо стоит ожидать появление Framework. Но информации по нему я не смог найти.
Я не знаю причин по которым две уважаемые организации представили, по моему личному мнению, сходные спецификации. Предыдущая история сосуществования SCORM (ADL) и IMS CP например показывала, что стандарты могут дополнять друг друга. В этот раз я не вижу такого дополнения.
