1. The Task Management Component (TMC) [Coad/Yourdon]
The OOD Process - IV
The Task Management Component
(TMC)
[Coad/Yourdon]

2. The OO Co-Design Process The Task Management Component
extend
HIC
TMC
PDC
DMC
high-level
Design
Miniworld
refine &
map
detailed
Design

3. TMC - What is it? Task: A stream of activity. Support in your OOD
multitasking
concurrency
priorities
transactions
set of activities as atomic action
role-back, commit, etc.
map your needs to the infrastructure
tool-specific solutions
guided by a common architecture

4. TMC tasks check the type of task(s) you need check priorities
event-driven tasks
clock-driven tasks
etc.
check priorities
identify a coordinator
define each task object

5. TMC tasks - types: event-driven I
life-cycle
task sleeps
triggered upon event & arrival of data
data line
data buffer
read & format data
place in an internal buffer (send messages directly)
notify objects.services
check on proper sequence
handle errors

6. TMC tasks - types: event-driven II
might be programmed as a “distributed“ solution
scenario as in OOA
error handling
low dependency of involved activities (services)
if any of the above conditions does not hold
centralized task object
in IS world: “transaction handler”
also called “controller”

7. TMC tasks - types: clock-driven I
life-cycle
task sets a wake-time and sleeps
triggered by time
read & format data (if necessary)
notify objects.services
check on proper sequence (if necessary)
handle errors
set a new wake-time
go to sleep

8. TMC tasks - types: clock-driven II
might be programmed as a “distributed“ solution or
centralized task object
less usual than for event-driven
complements event-driven tasks
in principal equivalent

9. TMC tasks - check priorities
priorities help to manage resources
not easy to design and implement
use existing task managers and priority schemata
indicates need for a coordinator
identify and isolate critical tasks
stringent reliability constraints
critical to the success or failure of the system

10. TMC tasks - identify a coordinator
task of tasks manager
three or more tasks
priorities and interrupts
complex transactions
adds overhead
encapsulates task-management
only trigger services, do not implement them in the coordinator

11. TMC tasks - define task objects
name
description
priority
services included
sequence of call
error handling
coordinates by
trigger or time (interval)
communicates via
data comes where from, goes where to

12. A Task-Object Pattern Task Coordinator coordinate task name
1,1
task
name
description
priority
services_included
coordinates_by
communicates_via
initialize
start
terminate

13. Use existing solutions.
Keep tasks to a minimum.
Use existing solutions.
Think in Architectures!