Basic Function

A basic function does not rely on any other cloud resource to be triggered. It can be invoked from other functions, possibly returning some data, or triggered on a cron schedule.

Basic Usage

A method is annotated with @BasicServerlessFunction. This allows it to be invoked by a BasicServerlessFunctionClient.

For example:

class BasicHandler {
    
    @BasicServerlessFunction
    public long getCurrentTime() {
        Calendar cal = Calendar.getInstance();
        return cal.getTimeInMillis();
    }
}

This function can then be invoked with no arguments using a BasicServerlessFunctionClient.

As with all serverless functions, a basic function must be inside of a class with a default constructor available.

Method Details

Parameters

Can have at most one parameter, a custom user type. This is deserialized using the jackson library so for more customisation annotations can be placed in the target class.

If it is a cron function then the method should have no parameters otherwise the function will fail (as no parameters are included in the request).

Return Type

The return type is serialized, again using jackson, and sent back to the invoker. If it is a cron function then this return type will be unused in the cloud provider, but can still be used to verify in unit tests.

Annotation Specification

@BasicServerlessFunction

Optional Parameters

• cron - A schedule expression of the form cron() or rate(). Specifies when to trigger the function automatically.
• timeout - How long the function is allowed to run for before timing out, in seconds. Defaults to 10.
• memory - The amount of memory the function runs with, in MB. Defaults to 1024.
• stages - The stages that the function is deployed to.