UML for Real-Time
Unified Modeling Language (UML) 
Real-Time Object-Oriented Modeling language (ROOM)

Observations motivate a scheduling problem of measurement
tasks for orchestrating them to prevent conflicts
while still satisfying their periodicity requirements. The nature
of the problem is similar to real-time scheduling even
though the time granularity of periods (order of minutes) is
much coarser than that of the classical real-time systems.

The scheduling problem, however, is not exactly
same as any of the existing scheduling problems in the realtime
literature, because the problem involves multiple measurement
servers running multiple measurement tasks whose
conflict dependency propagates along the chains of paths.
For this problem, we propose to use an EDF (Earliest Deadline
First) heuristic but allowing “Concurrent Executions”
if possible, to construct an offline schedule for a given measurement
task set.
• Offline scheduling algorithm based on
the EDF principle but allowing concurrent execution if
possible, which can significantly improve the schedulability
of a given measurement task set,
• Online mechanism that can steal the
maximum possible slack from the offline calculated
schedule to serve on-demand measurement requests as
soon as possible without violating the periodicity requirements
of all the given measurement tasks,
• Implement an NMI equipped with the
proposed scheduling mechanisms to measure the realworking
network, Internet 2 Abilene network

EDF-CE: For the given task conflict graph, find the measurement
schedule during a hyperperiod
Input: task set  and task conflict graph
Output: start time stij and finish time ftij for each job ij
in a hyperperiod

Connectors capture the key communication relationships between capsules
Ports provide communication access, define protocols 
Capsules correspond to actors in a system, interact through signals 
pending job queue that holds all jobs released but not scheduled, in the EDF order
progresses the virtual time variable time until a hyperperiod while determining the schedule at all scheduling time points, i.e., release
times and finish times
Measurement Level Agreement (MLA)
MLAs could specify that only a certain percentage
(1 - 5)% or only a certain number of bits per second (1-2)
Mbps of the network bandwidth in ISP backbones could be
used for measurement traffic

the algorithm tries to concurrently
start as many jobs as possible in the EDF order at
time as long as they neither conflict nor violate the MLA
Use: The developer recognizes that the requirement for latency, throughput, reliability, and availability are
far more stringent than for general purpose, or business software
EDF
Enhanced EDF Scheduling Algorithms for Orchestrating Network-wide Active Measurements
Measurement conflict
Monitoring network status
Internet Service Providers (ISPs)
Network Measurement Infrastructures (NMIs)
Active measurement tasks actively inject test packets to collect measurements along network paths, running multiple active measurements at the same time over the same path could
result in misleading reports of network performance.
Prasad Calyam (OARnet and The Ohio State University, Columbus, OH, pcalyam@oar.net)
Chang-Gun Lee†, Phani Kumar Arava, Dima Krymskiy (The Ohio Sate University, Columbus, OH, cglee@ece.osu.edu)


Field
Who's interested
Solution
Problem
Real-time detection of network anomalies 
Denial of Service attacks
Periodically run active measurement tasks using measurement servers located at strategic points in their networks
Problems in videoconferencing

The Algorithm
begin procedure
1. Initialize      rt list 

2. Initialize     ft list = {} 

3. Initialize      pending job queue = {}

STAR UML classic
UML RT
Standard
Loop
Hypothesis
ordered list of release times in a hyperperiod
ordered list of finish times
Goal
Why EDF
The result
Conclusion
Modeling a RT algorithm using Star UML and UML for RT
Handra Stefan
Resitnec Dan
Tartan Cosmin
MSE I
RTSD project
Star UML can totally respects UML for RT standard
In UML RT, we can define basic entities that are more understandable
A developer cand better understand the dependencies between entities
Structural communication patterns can be represented
Documentation of steps, conditions, etc.

4. do
5. time = get the next scheduling time point from
rt list and ft list
6. add all newly released jobs at time to
pending job queue in EDF order
7. for each job ij in pending job queue in EDF order
8. if ij does not conflict with any of already
scheduled jobs and
9. scheduling ij at time does not violate MLA
constraint 
10. stij = time and ftij = time + ei
11. if ftij is later than the deadline of ij
12. return error /* infeasible task set */
13. end if
14. remove ij from pending job queue
15. add ftij to ft list in order
16. end if
17. end for
18. until time == hyperperiod
end procedure