• Tested on Python 3.9, 3.10, 3.11 and 3.12
• Types and code style checks with mypy, ruff
• hopeit.engine unit tested using pytest, required coverage > 90%
• HTTP server integration tests using pytest_aiohttp
• simple-example client-example and dataframes-example applications and plugins integration tests

Microservices with Data Streams

hopeit.engine is a library and runtime that allows development and deployment of event-driven applications in Python. It provides a way to create APIs, orchestrate workflows using data streams, test, deploy and scale services. It also provides a flexible way to design, understand, run and visualize your apps, events and data dependencies.

Fast and Robust: it relies on pydantic 2.x for dataclasses serialization and schemas, on aiohttp for web services and supports pluggable stream managers to connect to your preferred event queue like Redis Streams. It is async by default and performance is comparable to REST frameworks like FastAPI.

Data-driven & AI Applications: it is particularly well-suited for running data-driven applications like machine-learning training and serving thanks to the tight integration with pandas using the hopeit.dataframes plugin, allowing serialization and data transfer via endpoints and streams.

Typical installation to use aiohttp server and command-line utilities.

pip install hopeit.engine[web,cli]

To enable stream processing via Redis:

pip install hopeit.engine[web,cli,redis-streams]

hopeit.redis_streams

Plugin implementing backend to use Redis for stream processing in hopeit.engine.

pip install hopeit.engine[redis-streams]

hopeit.apps_client

Plugin to invoke other applications based on hopeit.engine using http GET and POST requests, with retrying and circuit breaker.

pip install hopeit.engine[apps-client]

hopeit.apps_visualizer

Plugin that displays a web page with event dependencies, allowing live monitoring of multiple application instances.

pip install hopeit.engine[apps-visualizer]

hopeit.config_manager

Plugin that exposes runtime configuration for servers. Enables hosts to be monitored with apps-visualizer.

pip install hopeit.engine[config-manager]

hopeit.log_streamer

Plugin that can be run in a separate process and parses logs from running hopeit apps, publishing relevant entries to a stream allowing live monitoring of applications activity.

pip install hopeit.engine[log-streamer]

hopeit.fs_storage

Python library that exposes helpers to persist data objects to local filesystem.

pip install hopeit.engine[fs-storage]

hopeit.redis_storage

Python library that exposes helpers to persist data objects to Redis.

pip install hopeit.engine[redis-storage]

hopeit.dataframes

Plugin to support working with pandas dataframes as they were objects, supporting them as web request and response payloads and transferring them through streams.

pip install hopeit.engine[dataframes]

AWS Support

Plugins supporting integration with Amazon Web Services can be found in hopeit.aws repository.

Small organizations: hopeit.engine is intended initially to enable small organizations and companies, which don't have a huge software development infrastructure, to create new systems with the benefits of microservices: quick to develop, simple and small, easy to maintain and operate. These characteristics allow also migration of existing systems piece by piece to microservices. But that's not all: hopeit.engine adds a few features and good practices that all production-grade microservices must have out-of-the-box: modularity, scalability, logging, tracking/tracing, stream processing, metrics and monitoring.

Easy learning: if you want to learn how to develop microservices, hopeit.engine is a good starting point, since it will quickly make you productive and at the same time you will learn all the necessary steps and features that a production-grade microservice should have. Only basic Python knowledge is required. hopeit.engine was successfully adopted by Full-stack and Backend Software Developers, Data Engineers, and Data Scientists coming from different backgrounds.

Data-driven: hopeit.engine was thought keeping in mind that most business logic and decisions are, and will be, driven by data. Working with data is a key part of the library. We embrace pydantic dataclasses and enforce data-types checking on input and output data. The library and plugins provide OpenAPI validation and documentation and a way to share data between applications using streams. hopeit.engine is Data Science/Machine Learning friendly. We try to keep the library compatible with Python ecosystem around Machine Learning: Pandas, Jupyter Notebooks and the Scientific Stack. We aim to enable Data Teams to create their own services in a way people with different skills can contribute.

Streams: hopeit.engine provides the main necessary features for your system to accomplish the objectives of modern, reactive systems: responsiveness, resiliency, scalability and message-driven. The architecture enforced by hopeit.engine will lead you to develop small stateless services, primarily running asynchronous operations, that can recover from failure, can scale up quickly and handle more load, and communicate asynchronously with other services and process data using streams.

For production: With already a few years used in different organizations, we aim to ease the steps needed to put microservices in production. hopeit.engine provides out of the box logging of app events with extra information that allows monitoring, tracking, and measuring requests. It's easily configurable to run in containers and allows extensibility using plugins to add the pieces you need to integrate new microservices into your organization: i.e. plugins are available to integrate authentication and monitoring into your existing infrastructure. The way applications are structured allow for flexible deployment using Docker Containers and Kubernetes.

Check out our docs and tutorials.

hopeit.engine was adopted by the following non-profit organizations:

National Council of Volunteer Firefighters adopted hopeit.engine to create new applications, including APIs for data integration, nation-wide real-time resources monitoring, Firefighters Academy, COVID-19 dashboards, to mention just a few examples. hopeit.engine leverages for this organization the ability to ease development of new features at fast speed and allows them to integrate onto the existing software and decouple components using Microservices architecture.

Social Security Fund for Lawyers and Attorneys of Santa Fe, uses hopeit.engine to automate analysis of texts using Natural Language Processing techniques, integrating relevant information into a workflow management system.

If you want to mention your organization, let us know by opening an issue:

• Enables the development of microservices in Python (3.9+).
• Provides a web server for API endpoints. *
• OpenAPI schema validation and docs. *
• Inter-app connectivity via http client with retrying and circuit breaker. *
• Modular and testable application design: each microservice is an app composed of independent events
• Metrics: event durations, events starts, success, failures. Stream processing rates.
• Tracking/tracing: keep track of request ids among applications and multiple events execution.
• Event publishing and consuming to Redis Streams. *
• Log processing.
• Apps and events dependencies visualization and live monitoring.
• Helps to create elegant and well structure code using your preferred IDE.
• Data Science / Machine Learning friendly: dataframes with schema support via the hopeit.dataframes plugin *
• Testing: provides utilities to test from Notebooks or Python testing frameworks.

hopeit.engine is Open Source, and we encourage people to adopt it, improve it, and contribute changes back. Check LICENSE file. The library also takes advantage of other well-known python open source libraries to deliver the features described above:

• HTTP endpoints and clients are based on aiohttp
• Dataclasses schemas and serialization are provided by pydantic
• Plugin for stream processing is supported using Redis and connected using aioredis
• Dataframes plugin is implemented using Pandas

For a full list of required libraries and licenses check THIRDPARTY file.

A few examples of how microservices can be architected using hopeit.engine

App: is a conceptual unit implementing a cohesive piece of behavior, consisting of at least a configuration file plus a python module. An app implements one or many Events.

Event: is the basic execution unit that is triggered when an endpoint is invoked, or a message is received from a stream. Events can be of GET, POST, STREAM or SERVICE types. GET and POST are triggered from HTTP calls, STREAM when a message is consumed from a data stream and SERVICE events can run continuously.

Steps: each Event can define a list of Steps to be executed when the event is triggered. hopeit.engine ensures the ordered execution of steps and dependency based on its inputs/outputs, allowing each step to be concise and independently testable.

Plugin: a special type of module that can extend the framework or other Apps functionality.

Server: a group of Apps and Plugins, a server configuration file plus an OpenAPI specification file can run together using hopeit.server.web module.

Check Simple Example Application for examples of supported event types, steps, configuration and OpenAPI specification files.

In this schema, we can see a service or App created using hopeit.engine. The app orchestrates the implementation for two Events, each one accessible using an API endpoint. When an external client sends requests to the route associated with the event, the engine will trigger the execution of the steps defined in the event. Multiple events are served concurrently (but not necessarily in parallel) using asyncio

Many Apps can generate a single API specification and run together in a service unit. This sometimes could be desired to simplify operations. This is useful in small organizations where you don't want to deal with a lot of microservices to manage at the beginning. Later on, the apps can be detached easily and run separately if required.

If an external request triggers a process that requires background tasks to run, the process can be split in many events, and even in many services using streams. In this example App 1 is receiving the request and can quickly respond to the client while submitting a message to a stream. This is easily configurable just adding a write_stream section on the App configuration file. Then a second microservice (App 2) consumes the messages in the stream and performs extra processing, in this example, finally saving the result to a database. This is a powerful tool for reactive systems to use. Streams are not only fast, but they allow to design the systems in a modular way, keep every piece small while providing resiliency especially on data processing scenarios. Check the tutorials on how to develop events that can publish and consume events from streams here

hopeit.engine enforces your Apps implementation to be scalable. We mentioned that events are served concurrently using asyncio, but to achieve real parallelism, many instances of an App can run in the same or different server instances. Putting a load balancer (i.e: NGINX or HAProxy, in front of your API Server app instances, will ensure serving a high load of requests in parallel. The same scalability/load-balancing pattern applies to stream events processing. You can run many instances of Apps consuming Redis Streams. By using consumer groups, Redis will act as a load-balancer and each App instance will consume events from the stream in parallel. Apps created with hopeit.engine are also easy to deploy in containers, like Docker. Only a Python runtime and a load-balancer is needed.

Please check the docs.

Thank you!