Actie: an Actor Framework for Stateful Serverless Functions

The advent of serverless computing has rapidly transformed the software development landscape by significantly reducing the effort required to build and maintain computing infrastructures. A key player in this transformation is the Function-as-a-Service (FaaS) model, which emerged in the early 2010s and is now supported by many leading cloud providers. FaaS has gained widespread popularity for enabling developers to build scalable, easy-to-deploy functions, billed on a per- invocation basis. This makes it a perfect fit for compute-intensive, highly parallelizable workloads such as Internet of Things and data processing. However, its adoption has been limited by inherent issues such as its low-level abstraction and stateless nature.

To address these challenges we present Actie, a framework designed to simplify the development of stateful and complex serverless applications. Actie’s main contribution lies in its programming abstraction, inspired by the actor model, which enhances FaaS-based applications by enabling a more intuitive design. In addition, Actie introduces a novel state management system, designed to be transparent to developers while improving performance. This mechanism leverages the local memory of serverless functions to create a caching layer, thereby reducing data access and persistence latency. To validate our concept, we implemented Actie on Apache OpenWhisk, a well-known open-source serverless platform. This practical showcase proves the framework’s effectiveness in real-world scenarios. When compared to traditional serverless implementations, Actie demonstrates notable improvements in terms of development complexity and runtime performance, highlighting its potential to contribute to serverless computing advances.

Credits

Actie is the outcome of the master's thesis research conducted by Matteo Merz at Politecnico di Milano. For further information, please consult the original document, available here.

Getting started

Actie Command-line Interface (CLI) is a tool that provides a consistent interface to interact with Actie services. Here a quick guide to install and initialize an Actie project.

Install Actie

First of all, clone the project. Then, move to the project folder and install the required dependencies

cd actie
pip install -r requirements.txt

Now you can install the framework itself

pip install -e .

Create an Actie project

To create a new Actie project, use the Actie CLI as follows

actie create <PROJECT_NAME>

In order to connect to OpenWhisk, you should provide the credentials to access an OpenWhisk running instance. Set them into the config.json file in the main folder of the project, toghether with the host of the storage server.

{
    "wsk": {
        "host": <WSK_HOST>,
        "auth": <AUTH>
    },
    "storage": {
        "host": <STORAGE_HOST>
    }
}

N.B. The OpenWhisk instance should be aligned with the forked version available here.

Build and deploy an Actie project

To deploy an Actie project, the first step is to build it, using the following command

actie build

It generates the executables of each defined actor. After that, you can simply use the following command to package and register these executable into OpenWhisk.

actie deploy

Invoke deployed actors

A deployed actor can be invoked by an OpenWhisk instance as follows.

import json
from lib import OpenWhisk

wsk = OpenWhisk.init()
wsk.invoke(
    <ACTOR_FAMILY>, <ACTOR_NAME>,
    json.dumps({
        'action': <STRING>,
        'args': <DICT>
    })
)