Definition
For OGHR, Platform needs to enable user to undertake exams. Platform should be capable of processing the user responses and evaluate these responses with relevant applicable scores. Outcome of this design should enable the platform users to take up examination with server side evaluation of results.
Background
In the present system, Question Set consist of following entities:
Entities
Assessment User : Active seeker of Assessment in the platform.
QuML Player : QuML Player has capability to play the questions in QuML format. It also has capability to locally validate the user input. Response Validation,Score Computing is completely handled in player. Once User Submits the overall response, client validated scores and response are updated using Content State Update API.
Flink Jobs : Flink Jobs aggregates the content state using Collection Activity Aggregator, Collection Assessment Aggregator, Cert Pre-processor, Cert Generator jobs.
Objective Types:
a) MCQ (Multiple Choice Questions)
b) MSQ (Multiple Select Questions)
c) MTF (Match The Following)
d) FTB (Fill in The Blanks)
Subjective Types
a) VSA - (Very Short Answer)
b) SA - (Short Answer)
c) LA - (Long Answer)
Building Blocks :
Building Blocks | API | Flink Jobs |
|---|---|---|
Sunbird InQuiry | Question Set Hierarchy API | |
Question List Read API | ||
QuestionSet Create API | ||
Question Create API | ||
Sunbird Lern | Content State Read | Collection Activity Aggregate |
Content State Update | Collection Assessment Aggregate | |
Enrollment List API | Cert Pre Processer | |
Cert Generator | ||
Sunbird RC | Cert Registry Download API |
Current Workflow
Design PreRequisites :
Allow the response processing of question to be done on server rather than client as happening today.
Scalable Response Processing Solution for Question Sets.
Score Calculation Based on Content State Update.
Solution to the question needs to be masqueraded or excluded from the Question Read API/ Question List API.
Response Processing can happen in two ways:
Entire Question Set Response Processing
Question by Question Response Processing
Solution Proposed
Proposed System:
Technical Design Details:
QuestionSet Hierarchy API : A new attribute in QuestionSet to be introduced to have evaluated response on server. (“evaluable“). Every QuestionSet Hierarchy will attach “QuestionSetToken“ based on encrypted value of user-id, questionset-id, collection-id.
"questionSet": {
"timeLimits": "{\"maxTime\":\"3600\"}",
"questionSetToken": "", //#Question Set Digest to be generated at hierarchy read API with combination of "Question Set ID + userID"
"evaluable": true //#true for Server Side Valuation Default:#false for client side validation
}
Question Read API : Any Question Associated with evaluable behaviour to trim off response declaration from Question Set. Instead a responseKey to be shared along with responseDeclaration. responseKey is encrypted value of response. This is permenantly persisted as encrypted. Only QuestionRead API with questionCreator access should be able to access the decrypted value on demand.
"evaluable": true,
"responseDeclaration": {
"response1": {
"maxScore": 1,
"cardinality": "single",
"type": "integer",
-- To be Trimmed off ----
"correctResponse": {
"value": "0",
"outcomes": {
"SCORE": 1
}
},
-- To be Trimmed off --
#Newly Introduced Attribute
"responseKey": "#Computed Hash/Encrypted Value of the result"
}
},
Question Create API:
It is possible to permanently mark the question to be “evaluable“ in nature. Any evaluable question would automatically qualify for evaluable question Set. These Questions can be part of Evaluable QuestionSet only. Question Read of Evaluable Questions should exhibit the behaviour mentioned above.
Question Creation API should accept the response from the Question Creator to generate the encrypted value of the response created. This responseKey will be persisted along with Question metadata. Since the actual response is encrypted there is no effective mechanism to derive the right answer. Any Subsequent question Read API will only generate responses with encryptString without actual result.
KeySet (Futuristic):
Any Responses on Question Set can be persisted separately to ensure the keyset can be used for administrative purposes.
QuestionResponseValidateAPI (Async API Behaviour):
API accepts the request payload similar to content state update API. Along with responseKeys in the assessment.
{
"request": {
"userId": "843a9940-720f-43ed-a415-26bbfd3da9ef",
"questionSetDigest": "",
"assessments":[
{
"assessmentTs": 1681284869464,
"batchId": "0132677340746629120",
"collectionId": "do_213267731619962880127",
"userId": "843a9940-720f-43ed-a415-26bbfd3da9ef",
"attemptId": "5486724f41afb4997118e6d97695684f",
"contentId": "do_2129959063404544001107"
},
responses:[{
"identifier":"<question-id>",
"questionType": "",
"userResponse":[""],
"responseDeclaration": {},
"responseKey":["<response-key>"]
}]
}],
"contents": [
{
"contentId": "do_2132671468826214401203",
"batchId": "0132677340746629120",
"status": 2,
"courseId": "do_213267731619962880127",
"lastAccessTime": "2023-04-12 12:56:45:687+0530"
},
]
}
}
The Above payload mimics ContentStateUpdate API to mimic responses as above.
Question Set Response Processing flow
Question Set Response Processing Hardening
In Order to minimise the possiblity of Exam Response replays or any other kind of malpractices. Following design enhancement is proposed.
Usage of QuestionSetDigest:
A Hash value of “user-id+questionsetid+timestamp“ is generated as questionSetDigest and sent to client as part of Question Hierarchy.
Same Digest is used in QuestionValidation API request payload to validate the userID and questionSetID tampering.
QuestionList Validation
In order to check for validity of Question inside a QuestionSet. Design proposes the value to be encrypted based on QuestionID List in hierarchy and persist this information against QuestionSetDigest in Redis.
console.time("dbsave");
var crypto = require('crypto');
var encryptList = [];
var string = "sdgxsoksgdaodjqwdhuwdh";
var count = 0;
var salt = "salty";
for(var i=0;i<1000000;i++) {
var encrypt = crypto.pbkdf2('secret'+i, salt, 10, 64, 'sha512', (err, derivedKey) => {
if (err) throw err;
});
encryptList.push(encrypt);
if(string === encrypt) {
count++;
}
}
console.log(count);
console.log(encryptList.length);
console.timeEnd("dbsave");
Response Times for Benchmarking
1000000 encrypt generation dbsave: 4011.281ms 100000 encrypt generation dbsave: 377.208ms 10000 encrypt generation dbsave: 57.326ms