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Sub Process vs Start Process

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In new 24.4 we have Synchronous and Asynchronous option for Start Process smart service . Then what's the difference between Subprocess Synchronous and Asynchronous things ?

james.leponeAnswer

Employee

You can see an outline of the differences in staring processes in the docs, here: docs.appian.com/.../Ways_to_Start_a_Process_From_a_Process.html

james.leponeAnswer

Employee

You can see an outline of the differences in staring processes in the docs, here: docs.appian.com/.../Ways_to_Start_a_Process_From_a_Process.html

M

mahalakshmim5743Author

New Participant

Thanks that was very useful

stefanhelzle0001

Brainy

I covered some aspects of this in my recent blog post on version 24.4.

https://appian.rocks/2024/12/09/appian-244-insights/

mikes0011

Brainy

AFAIK this is basically just a case of "feature convergence" - originally-separate features being fleshed-out (separately) to the point where they become nearly interchangeable, if not totally interchangeable.

They may be planning to phase out the classic subprocess node altogether - though it's impossible to say either way. The "start process" node needs a few more improvements before that can happen, though.

the node icon needs to let us differentiate synchronous from asynchronous, like the subprocess node currently does and traditionally always has
it needs to more-flexibly handle opening the subprocess from the parent level; running subprocess instances, for example, as well as subprocess model when defined by expression (at least when defined by something stupidly-easy / nonconditional, like via a single constant)
probably needs the ability to pass variables by reference, for the rare occurrence when it's the only way to handle something
when searching a model by name in the process model editor search bar, we need a way to "drag and drop" the target model as a Start Process node instead of (or preferably, in addition to) the classic subprocess node.

The Expression Guru

P

preethis609221

Participating Frequently

Activity Chaining in start process

The documentation says, we can't get the process variable back from child process. "Chaining through a synchronous Start Process node means the original process will wait for other process to complete before continuing. Any activity chaining in the started process is not connected to the original process, so a broken chain will not return process variables to the original process."

Synchronous Start Process

Here documentation says, we can take the output variable from child process.

Can anyone please clarify what it's referring to as per the latest updates in start process and sub-process?

james.lepone

Employee

What [mention:b45a4f6a20b14a008e4e0ec732a8bf98:e9ed411860ed4f2ba0265705b8793d05] said is right, a long term goal is to move away from the subprocess node and converge the features into one node, start process smart service. However, it is correct to say this requires more improvements and may take a long time, there is no set roadmap as of now.

[mention:4c466563ec39453099f2b9ae708b5bf1:e9ed411860ed4f2ba0265705b8793d05] The most important part of what is being said in that copied text from docs is that the start process smart service no longer (the version of the node prior to 24.4 does do this) uses activity chaining to define synchronous behavior. Instead, you define whether or not to run the child process synchronously in the node configuration (setup tab). If you choose to run the child process asynchronously, no output data is returned. However, if you choose to run the child process synchronously, then the PVs of the child are returned at the end of the child process, NOT the end of the child activity chain.

As to the chaining behavior: If you have an activity chain in your parent process, and that chain is on the flow before the Start Process node, the chain in the parent will wait for the entire child process to complete, that is, we are chaining through the child process rather than into the child process. This is akin to chaining through a call integration node, for example. The subprocess node chains into the child process, where the chain in the parent continues into the child. Start process does not work that way.

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