WebAssembly
as a Common Layer
for the Cloud-edge Continuum
Jämes Ménétrey, Pascal Felber, Valerio Schiavoni
University of Neuchâtel, Switzerland
Marcelo Pasin
HES-SO University of Applied Sciences Western Switzerland
University of Neuchâtel, Switzerland
Presented at FRAME 2022
The 2nd Workshop on Flexible Resource and Application Management on the Edge
Co-located with HPDC 2022
The 31st International Symposium on High-Performance Parallel and Distributed Computing
Minneapolis, United States, June 27 - July 1, 2022

Outline
 Introduction and motivation
 Building the continuum
 WebAssembly under the hood
 Performance
 Conclusion
FRAME 2022
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WEBASSEMBLY AS A COMMON LAYER FOR THE CLOUD-EDGE CONTINUUM

INTRODUCTION AND
MOTIVATION

The scenario in 2022
 Cloud applications are everywhere
 Cloud-backed handheld apps
 High availability and performance
 Flexible management
 Edge processing capacity is expanding
 Proximity, lower latency
 Legal compliance
 Internet of things is being deployed
 Small devices, simple tasks, user-centred
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Disconnected, incompatible silos
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BUILDING
THE CONTINUUM

A continuous environment
 Ideal integration of different silos
 Common execution environment
 No unnecessary differences, seamless
 Java Virtual Machine
 Cloud-edge continuum system before its time
 Has become too large, too heavy (remember: IoT)
 Containers
 Fashionable today for deploying applications (microservices)
 There is one type for every architecture (not homogeneous)
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Security must be a birthmark
 Cloud applications are hard to fully trust
 Providers may be curious
 Other tenants may be malicious
 Edge applications are almost impossible to trust
 No physical control over the machines
 Providers do not trust users
 Edge and cloud are not under the same control
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Trusted execution environments
 Hardware extensions, TEEs
 Available in most current architectures
 Intel SGX, Arm TrustZone, etc.
 Isolated, trusted hardware partitions
 Virtually impossible to tamper with a trusted program
 Not even the lowest level of software can
 Remote attestation
 Proves that a given program is running in the TEE
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Managing the continuum
 Management is orthogonal to our proposal
Discovery, allocation, deployment
Access control, authentication
Federation, aggregation, abstraction
 Manage the continuum remains a challenge
Much easier if the machines run the same software
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WEBASSEMBLY
UNDER THE HOOD

WebAssembly
 Bytecode for the web browsers
 Intended to replace JavaScript for compute-bound operations
 Backed by the big ones: Microsoft, Google, Mozilla
 Several languages can be compiled to WebAssembly
 Compact, few dependencies
 Sandboxing (as in browsers)
 Already being used by standalone applications
 Portability
 Common development (server and client)
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WebAssembly and TEEs
 WebAssembly executed inside TEEs
 Twine
WebAssembly TEEs using Intel SGX
 WaTZ
WebAssembly TEEs using Arm TrustZone
Added remote attestation
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Live migration
 Migrations add flexibility to the continuum
 Applications can start in the cloud and move closer to the users
 Same for the other way around (from the edge to the cloud)
 Migration can be a headache
 Segmented memory, indexed structures
 Complex systems resources
 WebAssembly helps migration
 Sandboxing, linear address space, well-defined system resources
 But… it’s still hard to migrate an open socket in 2022
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Limitations
 WebAssembly is still incomplete
Compiling a large application is still a challenge
 WebAssembly is still slow
JIT compilation, AOT compilation, work in progress
 There is a trade-off for speed
Interpreters are smaller, but slower
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PERFORMANCE

Measuring performance
 How slow is WebAssembly?
 We did a few comparisons of WebAssembly vs. native execution
 Tested hardware
 Intel Xeon E3-1275 server
 NXP MCIMX8M Arm-Cortex-A53
 Applications
 Polybench/C (compiler performance)
 SQLite Speedtest1
 Compared using ahead-of-time compilation
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Performance results
 Slowdown (different max & min depending on architecture)
 Intel 0.8 < slowdown < 3
 Arm 1 < slowdown < 2.5
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Polybench/C
SQLite Speedtest1

CONCLUSION

To conclude
 Our vision for the cloud-edge continuum
 An interoperable, scalable and distributed system
 Heterogeneous hardware, same type of software anywhere
 We hope this will transform the app ecosystem
 Developers will focus more on the business value
 Less dealing with the complexity of the infrastructure
 WebAssembly seems to be a perfect fit
 It abstracts the operating system, device, language
 TEEs can provide the necessary security
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Remaining challenges
 Many challenges remain
 Widening the programming language spectrum
 Extending WebAssembly system interface
 Supporting neural networks or parallel programming
 Building middleware to connect the continuum and compose apps
 Facilitating the deployment and migration of applications
 Taking into account latency, computation power, localisation
 Yet, we are confident that WebAssembly and TEEs are good
foundations to develop future large-scale systems
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Acknowledgements