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Connecting Smirkboard to Perception via Sweet.net
Applications summary
• Smirkboard– A tool to host audio visual presentations– Allow viewers to shared-annotate such presentations– Administrators can associate presentations with
particular groups
• Questionmark Perception– A tool for hosting online quizzes– Administrators can associate quizzes with particular
groups
Technical Scenario
Sweet.net
IIS
ENTERPRISE
WEBSERVICE
RemoteDatabase Your Web Application
Web Interface
Enterprise Method CallsreadPerson()readGroupsForPerson()
Motives
• Practical: to avoid duplication of data between systems used in a Masters’ module
• Idealistic: to establish a system where the adding of new data sources for access control purposes was really simple
Authentication & Provisioning
• Check username & password against record in external data source
• On success bring in all group and membership info
• Within Smirkboard maintain records of group and media associations
Issue (1) -
• Questionmark Perception encrypts Instructor passwords but not student passwords
• Therefore authentication of students was possible but not lecturers
Issue (2) – Obtaining Persons Based on Role
• You obtain Persons in IMS Enterprise only through their membership of groups
• However, it does have provision for defining roles– SystemRoleType– InstitutionalRoleType
Why would you need lists of Persons based on role?
• Give management rights over assets to fellow instructors
Issue (3) Transience of Data
• Typically user details as they visibly appear in any web application is likely to be sourced from some kind of sql statement invoking the user table whose contents are more or less permanent
Typical Discussion Board
• Usually a system will list contributions to a discussion board by iterating over a join between a table of comments and a table of users– I think x is great by Johnny
• I agree by Jane• I disagree by Peter
Discussion Board PseudoCode
Rs = new recordset(“Select * from comments,users where comments.userid = users.id”)
While not rs.eof
print “<BR>” & rs(“title”) & “ by “ & rs(“username”) & “<HR>”
rs.moveNext
End While
The Heather Case
• Suppose a student enrols at uolife.ac.uk to do a course in Estate Management
The Heather Case
• Suppose a student enrols at uolife.ac.uk to do a course in Estate Management
• She gets given an email address [email protected]
The Heather Case
• Suppose a student enrols at uolife.ac.uk to do a course in Estate Management
• She gets given an email address [email protected]
• In her second year she gets married and changes name to [email protected] and then takes a break from her studies
Returns
• However she comes back to her course 2 years later with her domestic circumstances changed, and instructs central admin to change her moniker back to [email protected]
Returns
• However she comes back to her course 2 years later with her domestic circumstances changed, and instructs central admin to change her moniker back to [email protected]
• She makes a request to the university authorities that all previous transcripts and records of her activity on the student intranet should use her maiden id
Traditional vs SOA-style treatment of user data
• In the traditional example of the db driven web app – it becomes a trivial task to change her name in her student record to change the name appearing by her contributions
Traditional vs SOA-style treatment of user data
• In the traditional example of the db driven web app – it becomes a trivial task to change her name in her student record to change the name appearing by her contributions
• In an context where user data is supplied by calls to a web service there comes a very complicated tradeoff to weigh up
No Permanent User Table - consequences
• We can either have ids stored in the comments table which relate to the user in the remote database– But everytime we iterate over the comments to
produce the discussion page, we would have to make webservice calls for each contribution
No Permanent User Table - consequences
• We can either have ids stored in the comments table which relate to the user in the remote database– But everytime we iterate over the comments to
produce the discussion page, we would have to make webservice calls for each contribution
• More likely we have full text field containing the user’s name at the moment of posting– But then Heather is forever McCartney!!!
Why not just have a temporary user table in the “consumer” web app?
• Because hmills might also leave the university – (and her record might be deleted in the remote database)
• That would mean that in a join between a temporary users table and the permanent comments table, her comment would not figure
• But should her comment be expunged just because her being has been expunged from the university, just as she has from Mr McCartney’s life?
Being Serious
• There will always have to be a complex act of reconciliation between the contents of the remote database (persons,groups,memberships) and the persistent traces they leave in an Enterprise consuming web application
• These traces could be:– The actions of a group while its membership changes
in a remote database– An individual’s progression through a learning design
while their name/title/nickname/status (e.g they haven’t paid their fees) changes in the remote database
Potentially 3 models of dealing with data transience
• (1) total transience: during sessions maintain and verify huge session objects with a list of group memberships which gets negotiated with Smirkboard on every transaction
• (2) moderate transience: every log-in, populate a db table with temporary list of group memberships and flush on next login before repopulation
• (3) small transience: effectively make Smirkboard a “shadow” of Perception, every so often just comparing its memberships and aligning them
Service Oriented Architecture for User Data Conclusions
• For certain uses it offers a compelling case– An application can be written away from the vagaries
of individual db setups – merely requiring that a standard implementation of an ims enterprise service is present
– But with applications of real complexity where user actions have persistent consequences then the complexity of thought required to implement it might make the tradeoff between ease-of-development vs transferability lead developers to renounce the goal of transferability
