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Exercise Management and Sheets

This page describes a major part of the STAT System XCend Schema, namely the exercise management, including groups, sheets and student results.

Schema

  element exercises {               
    element exercise * id {         
      attribute lecture             { string }
      attribute term                { string }
 
      element assistant * account   {[ exists //accounts/account[./account] ]}

    element group * id {        [ count(./id, ..exercise/student/group) <= ./maxSize ]
      attribute day             { "Monday" | "Tuesday" | "Wednesday" | "Thursday" | "Friday" | "Saturday" | "Sunday" }
      attribute time            { string }
      attribute location        { string }
      attribute curSize         { integer [ . = count(../id, ..exercise/student/group) ]}
      attribute maxSize         { integer [ . >= 0 ]}
 
      element tutor * account   {[ exists /account[./account]/tutor[..exercise/id]/group[..group/id] ]}
    }

      element sheets {              
        element sheet * id {        
          attribute maxPoints       { double [ . >= 0 ]}
        }                           
      }                             
      element students {            
        element student * id {      [ exists //accounts/account/student[./id] ]
          attribute group ?         { ident [ exists ..exercise/groups/group[.] ]}
          element result * sheet {  [ exists ..exercise/sheets/sheet[./sheet] ]
            attribute points        { double [ . >= 0 && . <= ..exercise/sheets/sheet[../sheet]/maxPoints ]}
          }                         
        }                           
      }                             
    }                               
  }

Procedures

Change Attributes

changeAttributes(ident uid, ident id, string lecture, string term) {
  assume exists /account[uid]/admin || exists /account[uid]/assistant[id];
 
  assume exists /exercise[id]; # implicitly true in OO implementations
 
  update /exercise[id]/lecture lecture;
  update /exercise[id]/term term;
}

Assistant Management

The procedures from User Accounts and Roles for the assistant role can be directly reused.

grantAssistantRights(ident uid, ident username, ident exerciseId) {
  assume exists /account[uid]/admin;
 
  assume exists /account[username]; # implicitly true in OO implementations
  assume exists /exercise[exerciseId];
 
  assume not exists /account[username]/assistant[exerciseId]);
  assume not exists /exercise[exerciseId]/assistant[username]; # implied by integrity and the assumption before
 
  insert /account[username] <assistant exercise=[exerciseId] />;
  insert /exercise[exerciseId] <assistant account=[username] />;
}

revokeAssistantRights(ident uid, ident username, ident exerciseId) {
  assume exists /account[uid]/admin;
 
  assume exists /account[username]/assistant[exerciseId]; # implies the account exists, which is implicitly true anyway
  assume exists /exercise[exerciseId]/assistant[username]; # implied by integrity and the assumption before
 
  remove /account[username]/assistant[exerciseId];
  remove /exercise[exerciseId]/assistant[username];
}

Group Management

The tutor role from section User Accounts and Roles and the students depend on groups, which restricts deletion.

createGroup(ident uid, ident id, ident groupId, string day, string time, string location, integer maxSize) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id];
  assume not exists /exercise[id]/group[groupId];
 
  assume maxSize >= 0;
  assume day = "Monday" || day = "Tuesday" || ...;
 
  insert /exercise[id] <group id=[groupId] day=[day] time=[time] location=[location] curSize=[0] maxSize=[maxSize] />;
}

deleteGroup(ident uid, ident id, ident groupId) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id]/group[groupId];
 
  assume size(/exercise[id]/group[groupId]/tutor) = 0;
  assume count(groupId, /exercise[id]/student/group)) = 0;
 
  remove /exercise[id]/group[groupId];
}

Group Procedures

changeAttributes(ident uid, ident id, ident groupId, string day, string time, string location, integer maxSize) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id]/group[groupId]; # implicitly true in OO implementations
 
  assume maxSize >= 0;
  assume /exercise[id]/group[groupId]/curSize <= maxSize;
 
  update /exercise[id]/group[groupId]/day day;
  update /exercise[id]/group[groupId]/time time;
  update /exercise[id]/group[groupId]/location location;
  update /exercise[id]/group[groupId]/maxSize maxSize;
}

Sheet Management

The student results depend on sheets.

createSheet(ident uid, ident id, ident sheetId, double maxPoints) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id];
  assume not exists /exercise[id]/sheet[sheetId];
 
  assume maxPoints >= 0;
 
  insert /exercise[id] <sheet id=[sheetId] maxPoints=[maxPoints] />;
}

deleteSheet(ident uid, ident id, ident sheetId) {
  assume exists /account[uid]/assistant[id];
 
  assume exists /exercise[id]/sheet[sheetId]; # implies existence of the exercise
 
  assume size(/exercise[id]/student/result[sheetId]) = 0;
 
  remove /exercise[id]/sheet[sheetId];
}

Student Management

Students themselves depend on an account, but nothing depends on them; Their results stand for themselves.

Transcend

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