Host a Custom Skill as a Web Service

You can build a custom skill for Alexa by implementing a web service that accepts requests from and sends responses to the Alexa service in the cloud.

The web service must meet certain requirements to handle requests sent by Alexa and adhere to the Alexa Skills Kit interface standards. For more information, see Host a Custom Skill as a Web Service in the Alexa Skills Kit technical documentation.

ASK SDK Web Service Support

The Alexa Skills Kit SDK (ASK SDK) for Python provides boilerplate code for request and timestamp verification through the ask-sdk-webservice-support package, which integrates with the Skill Builder object. This package only provides the verification components and a base handler to call the skill invocation, and is independent of the underlying framework used for the web application development.

Installation

You can install the ask-sdk-webservice-support package through pip.

Generic Web Service Handler

The WebserviceSkillHandler class registers the skill instance from the SkillBuilder object, and provides a verify_request_and_dispatch method that verifies the input request before invoking the skill handlers.

You can enable or disable request or timestamp verification for testing purposes by setting the boolean parameters verify_signature and verify_timestamp on the WebserviceSkillHandler instance. You can also provide additional custom verifiers that need to be applied on the input request before skill invocation.

The verify_request_and_dispatch method takes the http_headers and http_body from the web service, and returns the response in string format, on successful skill invocation. You have to convert the input and output into the web service-specific request and response structures.

Usage

from ask_sdk_core.skill_builder import SkillBuilder
from ask_sdk_webservice_support.webservice_handler import WebserviceSkillHandler

skill_builder = SkillBuilder()

# Implement request handlers, exception handlers, etc.
# Register the handlers to the skill builder instance.

webservice_handler = WebserviceSkillHandler(
    skill=skill_builder.create())

# Convert the HTTP request headers and body into native format
# of dict and str respectively, and call the dispatch method.
response = webservice_handler.verify_request_and_dispatch(
    headers, body)

# Convert the response str into web service format and return.

Framework-Specific Adapters

Flask and Django are two web service frameworks that are commonly used to build web services in Python. The ASK SDK provides framework-specific extensions to the ask-sdk-webservice-support package for both Flask and Django that handle the request and response conversion internally. This provides an easy way to integrate SDK skills that you've already developed to make them work with your web service.

flask-ask-sdk Extension Package

The flask-ask-sdk package provides a Flask extension that can register a Flask application along with a custom skill. It also provides helper methods to register the skill invocation as a URL endpoint to the Flask application.

The flask-ask-sdk package follows the Flask extension structure. The SkillAdapter class constructor takes the following:

  • A skill instance.
  • A skill id to register the skill instance in the extension directory.
  • An optional flask application, to register the extension in the application.

The class also provides an init_app method, to pass in the Flask app instance later, to instantiate and configure the extension.

The request and timestamp verifications are enabled by default. You can use the app configurations VERIFY_SIGNATURE_APP_CONFIG and VERIFY_TIMESTAMP_APP_CONFIG to disable or enable the respective verifications by setting boolean values to them.

You can use the SkillAdapter's dispatch_request method to register the skill as an endpoint url-rule. It handles the request and response conversion, request and timestamp verification, and skill invocation.

Installation

You can install the flask-ask-sdk package through pip.

Usage

from flask import Flask
from ask_sdk_core.skill_builder import SkillBuilder
from flask_ask_sdk.skill_adapter import SkillAdapter

app = Flask(__name__)
skill_builder = SkillBuilder()
# Register your intent handlers to the skill_builder object

skill_adapter = SkillAdapter(
    skill=skill_builder.create(), skill_id=<SKILL_ID>, app=app)

@app.route("/")
def invoke_skill():
    return skill_adapter.dispatch_request()

django-ask-sdk Extension Package

The django-ask-sdk extension package provides a Django extension that you can use to register a custom skill as an endpoint in the Django application.

The extension provides a SkillAdapter view class. You can instantiate the view class with a custom skill instance, built through the ASK SDK Skill Builder object, and register it in the urls.py file of the Django app so that the skill is invoked at the corresponding endpoint.

The request and timestamp verifications are enabled by default. You can use the constructor arguments verify_request and verify_timestamp to disable or enable the respective verifications by setting boolean values to them.

Installation

You can install the django-ask-sdk extension through pip.

Usage

If you develop a skill using the SkillBuilder instance, then you can use the following in example.urls.py to register it as an endpoint in a Django app called example:

import skill
from django_ask_sdk.skill_adapter import SkillAdapter

view = SkillAdapter.as_view(skill=skill.sb.create())

urlpatterns = [
    path("/myskill", view, name='index')
]
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Last updated: Nov 28, 2023