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Temporal .NET – Deterministic Workflow Authoring in .NET

temporal.io

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Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#41

Post by kkoste »

lorendsr wrote: post #2

For those not familiar with workflows as code, a workflow is a method that is executed in a way that can't fail—each step the program takes is persisted, so that if execution is interrupted (the process crashes or machine loses power), execution will be continued on a new machine, from the same step, with all local/instance variables, threads, and the call stack intact. It also transparently retries network requests…

What's the difference between workflows as code and using an eventbus? Or is the same? With RabbitMQ if a machine dies whilst processing message it will automatically requeue that message such that another consumer can process it.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#42

Post by overbytecode »

avdempsey wrote: post #38

We’ve been using temporal (the Python SDK) for some new projects at Internet Archive. It’s early days but we’re very excited. We run our own infrastructure, and we get more power-loss events or other intermittent issues than most. The durable execution of workflows that temporal promises seems like it was made for us. And once code is “temporalized” we get to eject a bunch of ad-hoc resiliency stuff into the sun, and…

Can I ask what issues or difficulties you faced going the self-hosting route? We’re a small outfit and we’re thinking of self-hosting temporal to save costs, would be interested to hear about your experience.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#44

Post by kodablah »

overbytecode wrote: post #43

I’m confused on something. What’s the difference between Temporal and something like Dagster/Airflow/Prefect? Is there a difference between ETL and workflows? Or is just branding?

From my limited understanding, Dagster and Airflow are limited DAG-based tools compared to Temporal that lets you write your logic in the programming language directly (loops, conditionals, coroutines, other libraries, etc) so long as you remain deterministic. Prefect I am also not that familiar with so I can't tell if their "flows" have limited logic they can do from Python, but they do not seem to support things like signals/queries at first glance.

One big difference is those three are Python only, and Temporal is Go, Java, JS/TypeScript, Python, PHP, and .NET. Usually another difference between most workflow tooling and Temporal (granted I have not checked with these) is the care they take in handling errors, retry, replay, cancel, etc so that'd be worth checking as well.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#46

Post by kodablah »

progmetaldev wrote: post #24
kodablah wrote: post #22

Earlier quoted context omitted.

Hrmm, I will investigate using an expression tree for this (now's the time while it is alpha). I was hoping to avoid people having to create lambdas. I hope I don't run into overload ambiguity with the existing `ExecuteActivity` calls where you can just pass an existing method as Func param. I will investigate this approach, thanks! Of course the "Ref" pattern is user-choice/suggested-pattern, it's not a requirement…

If it's possible to use both approaches without cluttering your API, that may be the best solution. I know a lot of more junior devs that have a difficult time wrapping their head around expressions in C#. Excellent library!

After looking at it, I am concerned it is not possible for a clean experience. We have to give guidance and samples and we have to choose a way of referencing methods in those. Having ambiguous approaches is a bit rough. We may have to just move to expressions.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#47

Post by lorendsr »

kkoste wrote: post #41
lorendsr wrote: post #2

For those not familiar with workflows as code, a workflow is a method that is executed in a way that can't fail—each step the program takes is persisted, so that if execution is interrupted (the process crashes or machine loses power), execution will be continued on a new machine, from the same step, with all local/instance variables, threads, and the call stack intact. It also transparently retries network requests…

What's the difference between workflows as code and using an eventbus? Or is the same? With RabbitMQ if a machine dies whilst processing message it will automatically requeue that message such that another consumer can process it.

The major differences between an event bus and a workflow engine is the workflow engine:

- Creates and updates events/messages for you

- Maintains consistency between the events and timers and the state of the processing flow. More info on why this is important for correctness/resilience: https://youtu.be/t524U9CixZ0

The difference between workflow code and using an event bus is that with the former, the above is done automatically for you, and in the latter, it's done manually, which can be a lot of code to write and get right, and is harder to track/visualize what happened in production and debug. It would also take a lot of events to get an equivalent degree of reliability—the message processor would need to do a single step and then write the next event to the bus. So a 10-line workflow-as-code function would translate to 10 different events in the bus route.

Also, the event bus route doesn't have the new possibilities I listed in the parent comment.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#48

Post by lorendsr »

overbytecode wrote: post #43

I’m confused on something. What’s the difference between Temporal and something like Dagster/Airflow/Prefect? Is there a difference between ETL and workflows? Or is just branding?

ETL tools target that specific use case, versus Temporal workflows are much more general purpose—for any backend code you want to run reliably. I wrote some more about this here: https://community.temporal.io/t/what-are-the-pros-and-cons-o...

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#49

Post by blpanuto »

I am currently scouting temporal for a personal project of mine, and after about two weeks reading documentation and trying out the samples, it's almost second nature to me.

The Typescript SDK is amazing. It strikes a nice balance, being straightforward to use without most of the common pitfalls related to non-determinism, thanks to the Temporal SDK using Node's VM module to execute code with patched sources of non-determinism, like `Date` and `math.random`.

The only caveat is running it (Temporal Server). After mulling it over, for this project I sticked with running everything in a single VPS. If for some reason I get more users one day, maybe consider a Kubernetes managed service. Temporal Cloud is also an option, just not for me at the moment (region constraints, plus it's a pet project so no money)

But the local developer experience is actually amazing. Temporal is a joy all around, to be honest.

Re: Temporal .NET – Deterministic Workflow Authoring in .NET

#50

Post by progmetaldev »

kodablah wrote: post #46
progmetaldev wrote: post #24

Earlier quoted context omitted.

If it's possible to use both approaches without cluttering your API, that may be the best solution. I know a lot of more junior devs that have a difficult time wrapping their head around expressions in C#. Excellent library!

After looking at it, I am concerned it is not possible for a clean experience. We have to give guidance and samples and we have to choose a way of referencing methods in those. Having ambiguous approaches is a bit rough. We may have to just move to expressions.

I completely understand. Either way, I still think the library is great and appreciate the work done to create it.
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