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1 |
| -# Event driven processing of Application Packages with Argo Events and Workflows |
| 1 | +# Event-Driven Water Bodies Detection Using Argo Workflows and Argo Events |
2 | 2 |
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| 3 | + |
| 4 | +## Introduction |
| 5 | + |
| 6 | +This learning resource demonstrates an event-driven system for detecting water bodies using cloud-native technologies. The system leverages Argo Events to handle and react to external event sources and Argo Workflows to execute data processing pipelines, including a water bodies detection algorithm encoded in the Common Workflow Language (CWL). |
| 7 | + |
| 8 | +The workflow is triggered by events simulated through Redis, an external event source, which queries a SpatioTemporal Asset Catalog (STAC) endpoint. The STAC endpoint provides geospatial data, which serves as the input for the detection algorithm. The automation is achieved using Kubernetes-native tools, making the setup scalable, modular, and suitable for Earth observation and geospatial applications. |
3 | 9 | This project demonstrates an event-driven workflow for detecting water bodies in Sentinel-2 satellite imagery using Argo Events, Argo Workflows, and Calrissian.
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4 | 10 |
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5 | 11 | It utilizes a Redis stream to trigger workflows that process Sentinel-2 imagery and generate outputs using CWL (Common Workflow Language).
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6 | 12 |
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7 |
| -## What Are Argo Workflows and Argo Events? |
8 | 13 |
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9 |
| -### Argo Workflows |
| 14 | +## Key Components |
| 15 | + |
| 16 | +This setup integrates the following technologies and concepts: |
10 | 17 |
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11 |
| -Argo Workflows is a Kubernetes-native workflow engine that lets you define and run multi-step processes in the form of Directed Acyclic Graphs (DAGs). |
| 18 | +### Argo Workflows |
12 | 19 |
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13 |
| -Each "step" in a workflow can be a container or an operation, enabling automation of complex tasks like data processing, ETL jobs, or ML model training. |
| 20 | +* Automates the execution of tasks using predefined workflow templates. |
| 21 | +* Supports the execution of CWL workflows using Calrissian, a lightweight executor for CWL in Kubernetes. |
| 22 | +* Includes two templates: |
| 23 | + * CWL Execution Template: Executes general CWL workflows, such as preprocessing tasks. |
| 24 | + * Water Bodies Detection Template: Encodes the algorithm for detecting water bodies in geospatial data. |
14 | 25 |
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15 | 26 | ### Argo Events
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16 | 27 |
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17 |
| -Argo Events is an event-driven automation framework for Kubernetes. It allows workflows and other tasks to be triggered in response to various events, such as webhooks, message queues, or timers. |
| 28 | +* Provides an event-driven architecture for triggering workflows. |
| 29 | +* Uses a Jetstream Event Bus to handle event communication. |
| 30 | +* Includes: |
| 31 | + * Redis Event Source: Queries the STAC endpoint to generate simulated events. |
| 32 | + * Event Sensor: Listens for Redis events and triggers the water bodies detection workflow. |
| 33 | + |
| 34 | +### Redis as an Event Source |
| 35 | + |
| 36 | +* Simulates events by querying the STAC endpoint. |
| 37 | +* Acts as a lightweight, flexible mechanism to mimic real-time event streams. |
| 38 | +* Ensures seamless integration with Argo Events via an event source configuration. |
| 39 | + |
| 40 | +### STAC Endpoint |
| 41 | + |
| 42 | +* Serves as the primary data source, providing geospatial data in a standardized format. |
| 43 | +* Enables the workflow to focus on processing relevant datasets for water bodies detection. |
| 44 | + |
| 45 | +## High-Level Architecture |
| 46 | + |
| 47 | +The system is designed to handle the following flow: |
| 48 | + |
| 49 | +1. Event Generation: |
| 50 | + |
| 51 | +* Redis queries the STAC endpoint and generates events containing metadata about geospatial assets (e.g., imagery of specific regions). |
| 52 | + |
| 53 | +2. Event Propagation: |
| 54 | + |
| 55 | +* The Redis Event Source forwards events to the Jetstream Event Bus. |
| 56 | + |
| 57 | +3. Event Sensing and Workflow Triggering: |
| 58 | + |
| 59 | +* The Event Sensor monitors the Jetstream Event Bus for relevant events. |
| 60 | +* Upon detecting an event, the sensor triggers the execution of the water bodies detection workflow. |
| 61 | + |
| 62 | +4. Workflow Execution: |
| 63 | + |
| 64 | +* The Argo Workflow templates process the event's input data using the CWL-based algorithm. |
| 65 | +* The water bodies detection results are stored or published for further use. |
| 66 | + |
| 67 | +## Why Use This Setup? |
| 68 | + |
| 69 | +This setup showcases the power of combining event-driven paradigms with container-native workflows for scalable geospatial analysis. |
18 | 70 |
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19 |
| -By connecting event sources (like a Redis stream) to sensors that listen for events, you can trigger automated workflows. |
| 71 | +It is particularly suited for Earth observation and scientific workflows because: |
20 | 72 |
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21 |
| -## Overview |
| 73 | +* Scalability: Kubernetes ensures workflows can handle varying loads effectively. |
| 74 | +* Modularity: Components can be easily reused or replaced for other applications. |
| 75 | +* Automation: Events trigger workflows without manual intervention, enabling real-time processing. |
22 | 76 |
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23 |
| -The project workflow involves: |
| 77 | +Through this resource, you'll learn to implement a cloud-native pipeline for water bodies detection, which can be extended to other geospatial or scientific applications. |
24 | 78 |
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25 |
| -* Event Source: A Redis stream that holds Sentinel-2 image acquisitions. |
26 |
| -* Sensor: Listens for events from the Redis stream and triggers a workflow to detect water bodies. |
27 |
| -* Argo Workflow: Executes a CWL-based workflow using Calrissian to process Sentinel-2 images. |
28 |
| -* Calrissian: An execution engine for running CWL workflows in Kubernetes, integrated with Argo Workflows. |
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