<!-- -*- coding: utf-8 -*- -->
(2009-05-23)

Spooler

  - manages a queue of test jobs and several backends
  
  - public methods (used by frontends): 
  
    - getStatus
    
    - getBackends
    
    - getBackendStatus, 
    
    - getBackendInputFields
    
    - getBackendTestFields
    
    - appendJob
    
    - getResult,
  
  - normal progress: 
  
     - get spooler handle
     
     - append a job: use 'appendJob' (cf. 'BackendJob' for required 
       key-value-pairs) which will return a a job ID
     
     - get the result (used 'getResult' with the job ID; getResult 
       returns a dictionary)

  - public methods (used by 'backendctl'): 
  
    - addBackend
    
    - removeBackend


Backend

  - execute/process tests

  - attributes: id, name, version, input fields, test environments
  
  - public methods: execute, getInputFields, getTestFields, shutdown
  
  - normal progress:
  
    - spooler calls execute
    
    - execute calls process_execute, which must be implemented by each backend 
    
    - execute returns a dictionary


BackendJob/TestJob

  - at least a dictionary with key-value-pairs

  - required keys: backend, submission/testTerm

  - all other keys are specified by the backend's input schema 


BackendResult/TestResult

  - at least a dictionary with key-value-pairs
  
  - required keys: value, message

  *value*

  - normal case: True/False (e.g., Haskell or Scheme backend) or 0..100 
    (e.g., Keywords backend)

  - error case: a negative integer
   
    - undefinded error: -42
   
   
    - internal error (spooler): -100
    
    - authentication failed (spooler): -110
    
    - backend not registered (spooler): -120
    
    - backend already registered (spooler): -121

    - backend not found (spooler): -122

    - invalid or insufficient job data (spooler): -150

    - unexpected backend result type (spooler): -151

    - internal error during backend call or in backend (spooler): -152
 
    - internal error during job processing (spooler): -153
    
    - no result for a job (spooler): -160
   
   
    - internal error (backend): -200
  
    - authentication failed (backend): -210

    - internal error during test (backend): -215

    - no test data found (backend): -216

    - no test environment/specification selected (backend): -217

    - internal error during syntax check (ProgrammingBackend): -220
    
    - no compiler/interpreter defined (ProgrammingBackend): -221

    - internal error during semantic check (ProgrammingBackend): -230


  *message*

  - backend specific messages used as feedback