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). mcgredo@nps.edu

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

Simulation Deployment: Now

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

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)

Web Applications Web Browser Cloud Lives Here

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

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)

Cloud One thing that makes web apps compelling is the cloud

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

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

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

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

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

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

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

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)

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

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

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

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