XML request missing "imsx_messageIdentifier" payload

[ranacseruet]

We are trying this library for LTI integration in our Python/Django app and it mostly works like a charm. Great job there!

However, one issue we faced while integrating with Blackboard LMS LTI, that returns a 500 error code while syncing, though it accepts and syncs the grade as well. It most likely related to this issue: 1EdTech/basiclti-util-java#30

This is the request body looks like that we are sending from our side:

<?xml version='1.0' encoding='utf-8'?>
<imsx_POXEnvelopeRequest
    xmlns=\"http://www.imsglobal.org/services/ltiv1p1/xsd/imsoms_v1p0\">
    <imsx_POXHeader>
        <imsx_POXRequestHeaderInfo>
            <imsx_version>V1.0</imsx_version>
            <imsx_messageIdentifier/>
        </imsx_POXRequestHeaderInfo>
    </imsx_POXHeader>
    <imsx_POXBody>
        <replaceResultRequest>
            <resultRecord>
                <sourcedGUID>
                    <sourcedId>03050aac78e2ffe64d32d829c83e9d665d4d79f3bc3309bc91dbe402984eef2c:::db561a20-9c39-4f53-98f4-142bc545c032:::content:1376</sourcedId>
                </sourcedGUID>
                <result>
                    <resultScore>
                        <language>en</language>
                        <textString>1.0</textString>
                    </resultScore>
                </result>
            </resultRecord>
        </replaceResultRequest>
    </imsx_POXBody>
</imsx_POXEnvelopeRequest>

imsx_messageIdentifier does not have any valid value.

[ryanhiebert]

I do see that this is empty, as the error says: <imsx_messageIdentifier/>. Would you be willing to share the code that generates this XML? Also, would you perhaps have a link to pertinent docs on this field, so that I can figure out what care needs to be taken WRT this field?

[ryanhiebert]

@ranacseruet : Do you think you might be able to get me a minimal example of the problem that I can use as a test case?

[ranacseruet]

@ryanhiebert sorry about the delay, I missed the previous reply.

Code that building this element:
So, I think the library is constructing the element here:

lti/src/lti/outcome_response.py

Line 135 in 2e8719a

message_identifier = etree.SubElement(header_info,

But not being updated with the proper message identifier info.

Sample Code that results to this:
We are using it like this:

outcome_request = OutcomeRequest({
    'consumer_key': lms.lti_consumer_key,
    'consumer_secret': lms.lti_secret,
    'lis_outcome_service_url':
    lms_course.lis_outcome_service_url,
    'lis_result_sourcedid': sync_auth['lis_result_sourcedid'],
})
outcome_response = outcome_request.post_replace_result(
    student_grade_map[thm_user_id],
)

Affected LMS: Blackboard. You can reproduce it by simply testing with blackboard LMS. Where blackboard will accept the grades and update it, but will return a 500 status code as part of the response.

Potential fix:
I think this changes here gives and idea how the java library was fixed: https://github.com/IMSGlobal/basiclti-util-java/pull/31/files#diff-d953de832e77b16adc0630fb675a8512R567 . Basically setting it with current timestamp or so.

Let me know if you have any more questions about this.

[ranacseruet]

Update: we found that its possible to overwrite some attributes through constructor. So, adding this is currently solving the issue:

{
      ...
      'message_identifier': unicode(datetime.now()),
}

So, the constructor code looks like this:

outcome_request = OutcomeRequest({
    'consumer_key': lms.lti_consumer_key,
    'consumer_secret': lms.lti_secret,
    'lis_outcome_service_url':
    lms_course.lis_outcome_service_url,
    'lis_result_sourcedid': sync_auth['lis_result_sourcedid'],
    'message_identifier': unicode(datetime.now()),
})

However, as this is more like an implementation detail, developers using this library shouldn't really be aware of this and should be fixed inside the library itself.