Choosing between Lambda functions and activities

Lambda functions and self hosted activities have their own strength. Below table should help you to decide whether Lambda functions or activities (or combination of both) is more suitable for your need¹.

Features	Lambda functions	Activities
Access to specialized hardware	Not available. In Lambda function you can't access specialized hardware (e.g. GPU)	Available, self hosted activities can be executed on specialized machines or device.
Cancel the running task	Not available, you can't cancel a running Lambda function	Available, you can cancel a running activity
Timeout the running task	Available, you can configure the Lambda function to finish within a specific period	Available
Scalability	Available, out of the box	You have to put the efforts to start/stop additional workers
Human approvals	Available, Guflow provides intuitive signal API to support human approvals	Available
Choice of programming languages	You can write the Lambda functions in good number of programming languages	Guflow provides you rich APIs to develop the activities. Hence your first option will be .NET.
Cost2	Likely to be low because you will pay only for the time when Lambda functions are executing	Likely to be more because your worker machines(docker or EC2) will be up and running even when there is no active workflow
Host maintenance	None, AWS takes care of keeping the host, Lambda functions executes on, up to date.	You will be responsible for keeping the EC2 instance or container safe and up to date3

1. Guflow does not give preference to either Lambda functions or self hosted activities. With same ease you should be able to program Lambda functions and self hosted activities. In fact feel free to mix activities and Lambda functions in same workflow if that is what suites your need.
2. You should evaluate cost for your case independently.
3. You should evaluate update and upgrade process for EC2 instances or docker images.