1. Simulation as a Service, Scalability, and Network Architectures
Don McGregor
Research Associate
MOVES Institute
Understanding global peace and conflict means understanding of human communities in the midst of and in response to change. US Joint Forces Command noted that “changes in the strategic landscape… new technologies, and the adaptation and creativity of our adversaries will alter….operations a great deal. Here too, the past can suggest much about the future – the nature of change, its impacts on human societies….”
This presentation provides an overview of the project and research methodology, progress to date and planned go-forward efforts.
2008. The Joint Operating Environment, United States Joint Forces Command Center for Joint Futures (J59).

2. Simulation Deployment Models
How are simulations currently deployed?
How will they be deployed?
What are the impacts on scaling simulations?

3. Simulation Deployment: Now

4. Simulation Deployment: Now
Compiled C++/Java code installed on a desktop
The desktops are mostly local network, or possibly multiple-site but connected via TCP/IP
Can exploit broadcast and multicast—the networking gear helps scalability

5. Current Problems
It’s expensive and inflexible to deploy desktop applications
It’s expensive to upgrade or even just update
High management costs
Upgrades are slow to come because of the above (often multi-year product life cycles)

6. Web Applications
Web Browser
Cloud Lives Here

7. Web Applications
The business trend is to use web-based applications rather than desktop applications
Fast deployment of new software—update once on server, use on web browser, faster life cycles (sometimes days or hours)
Much cheaper
Exploit cloud on server side
Mobile devices welcome, agile across multiple architectures (Linux/Windows/Android/IOS etc)
But
Less capable than compiled applications (not as bad as you might think)
Some UI issues since it’s running inside a web browser

8. Web Applications
The economics of this are compelling, as a quick survey shows
Few write desktop mail applications anymore—gmail, Google Calendar, etc
Enterprise apps are mostly web based
Google Docs & Office Online vs. MS Office Desktop (limitations of the genre)

9. Cloud
One thing that makes web apps compelling is the cloud

10. Cloud
There are economies of scale for data centers, which drives the cost of compute cycles and storage down
At the limit, CPU and disk are free and infinite on the cloud (OK, not quite, but close and trending that way)
Able to flexibly get more when needed, scale down when not needed

11. Simulation as a Service
So, change the business model. Enables rental of simulation services from the cloud instead of buying & installing applications on the desktop
Can still do it the old way if you like, and own the server software, run on a government cloud
Analogous to Software as a Service
MS Exchange, Office Web Apps, Google Docs

12. Scalability for Simulations
Simulations are different from office applications
If you send an entity position update, potentially that has to go to all other simulation participants
In a virtual world “My position is (17, 23, 42)” may have to be sent to every other participant

13. Network Updates
(x,y,z)
On a LAN or some WANs we can use broadcast or multicast
to prevent having to send out N-1 repeats of the message

14. Scalability
In web networking technologies there is no broadcast or multicast. Everything is unicast
Websockets (TCP), WebRTC (UDP) Javascript in the web page
This means we need other techniques for what is called Area of Interest Management (AOIM) or Data Distribution Management (DDM)
We can’t rely on the networking gear to do this for us, as with bcast or mcast

15. Scalability
This moves the needle away from peer-to-peer architectures (classically DIS and HLA) and towards client-server architecture, since P2P often relies on bcast and mcast

16. Scalability
All the packets are flowing through the server a single server probably can’t handle it. That’s the bad news. But: • We have infinite CPU and disk on the server side, because that’s on the cloud, if we parallelize across multiple hosts • We can examine each packet and make decisions about what to send to each client. This reduces the bandwidth used and client load

17. Scalable Client-Server
Application servers
(clustered) do DDM
Databases
Web Resources
(maps, open
source data, etc)
Web Server
(can be clustered)
Existing Simulations
Clients
Cloud (server side, free and infinite CPU and storage)

18. Scalable Client-Server
The clients connect over unicast, send and receive all updates unicast
All updates go through the server side and can be examined on the server side
Existing simulations and protocols can be gateway’d
The DDM/AOIM can be spread across multiple CPUs on the cloud side. This lets us do elaborate and computationally expensive DDM on the server side.  CPU efficiency is not important on the cloud side
This doesn’t address latency

19. Server-Side DDM Thoughts
Flexibility is more important than efficiency
Scripting languages such as JavaScript are flexible; use this for a DDM language? NodeJS? Javascript executed from Java?
Perhaps the client can generate the filter scripts for the packets it desires and send these to the server
Unknown: what is the effect on latency? Needs an instrumented example to investigate

20. Server-Side DDM Thoughts
This is oriented towards DIS, but exactly the same problems occur in HLA; RTI implementations for the web will face the same issues
Likewise with WebLVC
The economic benefits of cloud-based simulation are likely to be so compelling that 25 year old assumptions about P2P DoD protocols may need to be rethought

21. Server-Side DDM
In general, the superior economics of the cloud and web-based simulation drive simulation to client/server over peer-to-peer
Possible issues with bandwidth, latency mean likely limited to ashore and small-to-medium virtual environments
Mashups with open source internet data sources—live feeds, map data, GIS data….
Optional changes to business model—buy vs. rent simulation software
Plenty of techniques for having existing and web-based sims co-exist
It’s a worthwhile research topic