W3C Workshop on Web and Machine Learning

🌱 A virtual event with pre-recorded talks and interactive sessions

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Minutes of 2nd Live Session (September 22 2020)

Scribe: Dominique Hazael-Massieux

Present: Dominique Hazael-Massieux, Roy Ran, Jason Mayes, Zoltan Kis, Liu Yaoming, Kelly Davis, Anssi Kostiainen, Takio Yamaoka, Chai Chaoweeraprasit, Yakun Haung, Mina Ameli,  Jay Kishigami, OnePlus 5T?, P Laszkowicz, Rowan, Christine Runnegar, Wenhe Li, Dengyu Guang, Mehmet Oguz Derin, Ningxin Hu, Anita Chen, Seongwon Lee, Rolf Fricke, Andrew Brown, Chun Gao, Fuqiao Xue, Sheela Kurupathi, James Powell, Qaing Chen, Jonathan Bingham,  Wolfgang Maass, Dan Druta, Irene Alvarado, Alberto Perez, Joshua Meyer, Kyle Philips, Marie-Claire Forgue, Wendy Seltzer, Theoharis Charitidis, Rachel Aharon, Bernard Aboba, Rafael Cintron, Benjamin Bogdanovic, Jun Weifu, Mirza, Ping Yu, Chris Needham, Mark Crawford, Zhenjie

Regrets: Sangwhan Moon, François Daoust,

Agenda - Slides

Anssi: Introducing live session #2. What will we cover today? Last Tuesday, we discussed opportunities and challenges, today focuses on Web Platform foundations, broken into two parts: creating and deploying models, and extended foundations for ML. We'll be looking at what ML practitioners do on a regular basis, but have been missing with on the Web. Web Platform Foundations: the missing parts.

A quick recap on practicalities: please raise your hand if you want to speak; introduce yourself if talking for the first time. Please help correct the minutes as needed. We're operating under the Code of Ethics and Professional Conduct.

Dom: please make sure to speak slowly to help the interpreter

Anssi: the goal of oru session today is to understand how machine learning fits in the Web technology stack; we have identified a number of discussion topics for today - we've picked "only" 6 topics today to leave enough time based on our experience last week.

The first half of the meeting will touch on ML model formats, protecting ML models, in browser training, and training across devices.

The second half will look at extending Web foundations for ML: in particularly how WASI-NN and WebNN related one with another, and will finish with heterogeneous parallel computing.

Considerations for creating and deploying models

ML model format #74

Anssi: Many talks touched on this topic. The high level issue is that there is no standard format for packaging & shipping ML models, and ML model formats evolve rapidly. A proposal that has emerged is to focus on an API that enables loading models rather than pick a particular format, which is what the community has already taken up. Sangwhan Moon (who is unable to join us today) mentioned in his talk that there is no consensus on a format at the moment. I'm inviting Jonathan to comment on this, as the author of ML model API explainer, based on the perspective of the TensorFlow team. What are the abstractions we should be considering on a long and short term basis?

Jonathan Bingham: First, in the ML space, there are multiple model formats that are in wide use today. TF is one of them (the one I'm most familiar with) - in addition to the TF models, there are ONNX models, CoreML models, many ML practitioners use PyTorch. What we've seen with all these formats is that they're evolving rapidly. TF has over a 1000 compute operations that have been defined, growing by 20%+ per year. The other formats have been growing rapidly. PyTorch has hundreds, all formats are growing around 20%+ per year. This growth and lack of stability makes us think it's not stable enough for standardization. We in TF think we have have an approach to deal with this, by defining compute at a lower level than operations, using e.g. MLIR, or compute primitives - these lower level compute elements can be composed to form operations, providing a smaller set that would need to be standardized.Our Recommendation would be to avoid premature standardization and hope that the field provides good solutions to this problem. I know that folks at other companies (incl Microsoft) have worked on ONNX which is meant as an interoperable format, which could be a great format for the Web. It too has been growing rapidly but with attention to backwards compatibility. It could be ONNX is a good long term solution, or MLIR as a good long term solution,  or support multiple formats as a long term approach. It feels a bit early to pick one.

Anssi: Inviting Chai, lead of DirectML and informed of ONNX to share his perspective based on his work on the WebNN which he co-edits with Ningxin

Chai: the ML space is still evolving; we have ONNX, TF, PyTorch and all the JS frameworks. Presenting a single API is a future prospect given these rapid evolutions. The way we look at these systems is that fortunately, every single framework or ML API turns out to be implemented using the front-end/back-end architecture - there is already the architecture that allows the FE to operate unchanged, while the backend could change. My direct experience with DirectML is that we built DirectML in the OS (in Windows) and it's used by multiplied FE frameworks, namely ONNX runtime, WindowsML, and recently TF. When you implement the BE you get to see the difference and the commonalities across these FE that you're serving. What's encouraging is that in the BE, it's not much different. That's how we're approaching the WebNN API design as well. We've looked across all these frameworks to find the commonalities across them to make sure that the spec can support the needs of all these frameworks. Some APIs / frameworks move faster than others

, but there is a lot of overlap across them and that works in our favor. We can keep making progress on what would be a Web backend API for ML, while we wait and see how developers eventually converge into some framework or APis in the future. TF.js is widely adopted, and ONNX is used a lot on desktop settings, so there may be convergence in the future, but we don't have to wait or to force that unification too early. That's the current line of thinking in the ML CG. The second thing about MLIR: it could become that binding between BE & FE in the most flexible way - as becomes evident in TFRT (?). It's quite promising - that development would help glue this in a better way moving forward.

Ningxin: I'd like to add one aspect that was mentioned in Jonathan's talk - we've found that there is actually the model execution time spent on compute-intensive operators - there aren't so many of them (e.g. Convolution, matmul). E.g. for computer vision, over 90% of time is spent on these operators. In the CG, we have started with a very small core set of operators focused on the most compute-intensive ones, which is enough to provide good hardware acceleration.

Dom: looking at this from a different perspective - would this work across platforms (desktop vs mobile) or OSes? How would a developer deal with this?

Chai: I believe the way to achieve OS portability is to have the framework sit on top of the Web API that can be implemented in the browser across different OS. e.g. if TF.js, currently sitting on WebGL could sit on top of WebNN (which brings it on par to native performance). WebNN can then build on top of the OS APIs which would help achieve OS portability, the OS then takes care of hardware portability.

Dom: how would that extend to the ML loader API?

Chai: I think that will become clearer in the future once we have a standardized backend.

Anssi: what about the role of converters - can anyone speak on this? TF and ONNX have converter projects - is that part of an interim solution?

Otherwise, it sounds like the proposed approach is our best bet for the time being

Dom: are we connected well enough with ONNX and MLIR to make sure we have stable alignments of interest? Are other long term candidates in this space we should establish connections with?

Anssi: we have good connection with ONNX; Jonathan has served as a contact point with MLIR, so there is a shared understanding of what everyone is doing.

Protecting ML models #67

Anssi: Protecting ML models; some ML providers need to ensure their models cannot be extracted from a browser app. E.g. the model is built and tuned to solve their business specific issues, and are not willing to share it with the world. The proposal is to investigate existing access control mechanisms for videos, learnings from 3D assets.

In the discussion in the GH issue, it became evident that the problem of content protection has emerged in many places: for videos in particular, for 3D assets in the game of Web based games. What we've learned from these efforts is that it's not an easy problem to solve. I would like to invite Jason Mayes to share his views from TF - his talk mentioned the requirements they've heard from ML providers.

Jason: Model security has been a big issue for us, which we can't solve without browser support. By default, ML can be explored or exported in a browser. There are use cases where this isn't a concern, but there are many use cases e.g. in the corporate ecosystem where ML models are the results of significant investments, large IPR assets. The only way to get these ML run in a way that keeps them protected is to do it server-side - with all the known issues (latency, privacy). Comparing it to video - videos are single files to be protected - in ML, we need to protect also pre- and post-processing operations. An approach might be to flag JS code as needing to run in a secure environment (e.g. protected memory) from the server, which would prevent the developer to pick into it.

Dom: browsers are expected to act as agents of the user - anything that puts them as odd to that is going to be a challenge - as W3C has experience in EME. @@@ comparison to native … Assuming we could do as Jason describes, this would become abused by spammers and other creative people when it comes to use other people's resources. Security protection. Understand that ML providers are putting efforts in shaping their models.

Users expect to use their devices, so i'm surprised they don't want to lose control. Native platforms.

Wendy: W3C Strategy lead and legal counsel . EME was controversial, faced formal objections and contested appeal over the presence of DRM in the platform. One of the issues raised there which would be a challenge here would be security considerations. How can we guarantee the security of a system where pieces of it are blocked from view? With ML, I could anticipate the questions being even greater on the security and privacy front - how do we guarantee to the  that the piece of code they're asked to run is safe, not privacy invasive, is not exfiltrating information, etc. I would expect that to be a challenging discussion - even if I understand the desire to to protect the asset.

Anssi: it was indeed controversial in the context video - possibly one of the most controversial technical issues in W3C's history. What would be a sensible next step in this space? Are requirements similar? How much would it help if we were just to "hide" these assets - making them more tedious to extract them? Or allow some level of obfuscate them? How hard do we need to make it to prevent access to them? We should understand the use cases, derive requirements and see what our options are.

Zoltan: would the model loader API that would take a URL and metadata on privacy/security considerations - the model would then not be exposed. Is that a feasible path forward?

Jason: in terms of obfuscation - that's a big no, there will be tools to un-obfuscate, so not a real issue, and the said providers will stick to server-side or native. Another point is that this may be linked to the ML model format - once we have a well-defined format, there could be guarantees that the format can't e.g. phone home, only for mathematical operations - that might help removing some of the security/privacy concerns.

Ping Yu: I'm from Google in the TFJS project; we've discussed this with a lot of clients and JS platform vendors - how they could create such a secure execution. There are 2 needs: IPR protection and user security. From the vendor point of view, the encryption layer usually implemented in native with negotiation with the server side for the keys. When the model is executed, it's executed in a separate context which isolates the memory from other JS. This gives some security to the model provider - it depends on how much the adversary is ready to invest in breaking the encryption. If everything is done on the client side, there will always be ways to reverse-engineer. To make sure users aren't exposed to malicious models, various browsers are applying heuristics to determine what makes a "safe" browser. Definitely a hard problem.

Dom: could we use a distributed approach where the latency-sensitive bits would be kept on the client stuff, and the IPR sensitive stuff would be left on the server-side, connecting the two with a low latency channel (e.g. WebTransport)

Ping: there have been explorations in this space indeed

Anssi: Let's look into this

Comments on Chat

Christine Runnegar: +1 to Wendy re security considerations, and ditto for privacy

In-browser training #82

Anssi: our current efforts are focused on inference rather than training. The proposal under consideration is to understand real-world usages (e.g. Teachable Machine) and target transfer learning as the initial training use case for browser related work. Inviting Irene and Kyle to share their experience with Teachable Machine.

Irene: I'm here with my colleague Kyle working with the creative lab at Google; we've worked with engineers to make ML technologies more accessible and easy for people to use. We've developed a project called Teachable Machine, a Web tool that allows training a classification model in the browser . (ML training code) You don't need to know anything about ML to use the tool - children as young as 8 years old have been using it successfully. You can create an image, audio or pose classification model (the latter based on PoseNet). It has been used to create games, engineers and designers have used it for prototypes, teachers have been using it. It's based on TF.js which is a key piece of our capabilities. In terms of in-browser training - we're using transfer learning: the training in the app is relatively quick because of that. In all cases, we're having the user re-training a 2-dense layers.  The tool makes it very easy to collect the samples, and the training happens in the browser. We lazy-load the base model in the browser - the size of the base models range from 1.6 MB to 6MB (for the audio one). We haven't focused on mobile too much, not so much because of hardware limitations, but more because of the UI which would have to be rethought quite a bit on mobile. Also, the WASM backend didn't exist for TFJs when we developed this last year - we would use it today. Another big motivation of using TFjs was privacy: none of the collected samples are sent to the server. The data can be optionally saved to a Google drive, but that's not a requirement, and it means people can train their models without ever sharing data with the server. One challenge we've hit is that it's really hard to show how long a training would take - if there was an API to help with that, it would have been really useful. This means it was also hard to give an estimate in the limits of the app - depending on the underlying hardware, you could use many different sample set sizes. We also wanted to make it possible to convert between models (e.g. TF to TF lite) - still lots of challenges in this conversion, which required a lot of custom code. We found that a lot of users didn't mind to wait a long time for the training to finish (e.g. up to 1/2h) - there are not so many tools that help achieve this with an easy tool, and then people were fine with the wait.

Anssi: very engaging tool - my 8 years old kid has used it successfully. It also drives the point that transfer learning is possible in the browser today. I heard your need for training time estimation - not sure we have any API for that; you also mentioned the problem with running training in a background tab - this could work with the System Lock API, I'll make sure this gets considered in the said work.

Irene: that's indeed was a challenge

Kyle: indeed, relying on requestAnimationFrame meant people were puzzled as to why their training was not proceeding. Another issue is memory usage: if loading a lot of images in a given tab, you might hit the limit. Also, different browsers have very different speeds, which can be hard to communicate to the end-user.

Anssi: there is ongoing work around memory usage

Dom: WebPerf has work on this https://github.com/w3c/device-memory/

Kyle: when starting a training, it can create an initial UI lock due to heavy compute usage - we didn't find a way to prevent that

Anssi: WebNN isn't focused on training in the current phase of our work; transfer learning sounds like the 1st initial use case we should look at for the future work in this space - Chai, what do you think?

Chai: WebNN is a graph API - that's good for transfer learning. That's one of the advantages of focusing on graph APIs. The model is able to implement transfer learning, but the exact API shape to make that happen is still to be discussed.

Oguz: I want to mention a possible use case of WebGPU in this aspect. Since WebGPU will make it easier to play around with synthetic data, people like authors of next generation textbooks might make use of it on topics like differentiable rendering by creating widgets that might demonstrate training of faster-to-converge networks, or maybe just some latents.

Irene: all of the ML code is open-sourced, so it could be reworked into different teachable machines!

Anssi: hopefully we can help make the platform even better in the future for this kind of project.

Training across devices #83

Anssi: this one is looking a bit further in the future - training across devices. The summary of this issue: we want to understand the role of edge computing in the platform. We would need to define edge computing among other things. Multiple talks touched this area, with federated learning, distributed learning, reinforcement learning. I would like to invite Wolfgang Maass to introduce thoughts on this.

Wolfgang: let me first introduce our research goals: consider any device belonging to a user as their agent, trusted with data and models allowed to operate on these data. As a user, I want to work with models in a very natural way: train it, merge it with other models that others have shared with me. Some models can be shared, some can't. There are also privacy issues - e.g. GDPR allows to stop sharing, which would apply here. We're working based on that perspective. All the tools that have been mentioned (TF, PyTorch, …) don't really provide that kind of flexibility to operate in multi-agent kind of systems. With federated learning, you always have different control formats. We're looking at enabling models for flow back and forth

Anssi: Thank you, your talk provides more details on this - go check his talk if you want to learn more. Inviting Yakun Huang to present his thoughts.

Yakung: from BPUT - edge computing can provide high-bandwidth / low latency with 5G. Edge computing would allow to provide high-computing from mobile Web to edge. To do that, you need dynamic offloading decisions based on dynamic network conditions and the status of mobile devices.

Anssi: I would like to invite Zoltan to share what's happening in the Web & Networks IG in this space.

Zoltan: Edge computing is a very broad topic - right now, the focus is computing offloading, with edge a particular focus due to lower latency. With regard to ML, the question is whether a generic computing is enough, or does it need to be specific to ML? If the latter, any hints as to what kind of accelerators would be preferred? What metadata about the compute loads would need to be shared to identify the right edge nodes? The IG has looked into various solutions using e.g. worker-based architectures, with links from the github issue. We're particularly interested in understanding what's needed to qualify a ML computing offloaded task.

Dom: +1 to Zoltan description - would want to hear from the ML crowd what role they see Edge Computing play in this space

Anssi: we're at the end of our scheduled time, with 2 issues left that will be rescheduled. Next live session tomorrow at the same time.