arc-arnob / columbia_use_case_software_architecture

BlazeGuard: Architecture for Firefighting Resource Management"

Defining the problem

1. Problem Description

In January of this year, Colombia experienced numerous wildfires¹, burning away tens of thousands hectares of wilderness². Even though the Firefighting Corps of the Nation are well trained in order to combat these emergencies, there are still challenges that they need to overcome to do so more efficiently. In particular, we want to focus on two pressing issues that hinder the corps in their efforts for the specific case of Colombia:

• Difficulty in coordinating resources during emergencies.
• Difficulty in detecting wildfires.

Our mission is to help in the protection of Colombia's wilderness and communities from the devastating impact of wildfires by delivering cutting-edge software technology that aids in wildfire detection and resource management.

1.1 Analysis of Existing Solution

To understand how these issues are identified and why they are present, we have delved into the management of wildfires in Colombia today. The protocol used by the Firefighter Corps in Colombia is called the Incident Command System (ICS), and was originally designed in the US, and further adapted to a general use within South American countries³. This protocol consists of 8 steps that are followed until the emergency is contained⁴:

• Inform the base of arrival to site.
• Take command of the situation and establish a command post (CP).
• Evaluate the situation.
• Establish a security perimeter.
• Define objectives.
• Define strategies.
• Determine Resources needed.
• Prepare the information to transfer command. To follow the protocol, the Corps are provided with a software to optimize their efforts. This software consists mainly of a digital platform for filling documents to track everything that can occur during emergencies [Appendix A], with some extra functionalities that can help in the planning of tasks. Based on the review of the existing software (which mainly focuses on the ICS) and interviews of a Volunteer Firefighter ⁵, we found two challenges that the ICS protocol does not handle.

Most of this information, and information presented in the section 1.2 was obtained by means of an interview with a Volunteer Firefighter in Bogotá. The video interview and transcript is present in Appendix C.

1.2 Main Challenges

Difficulty in coordinating resources during emergencies.

Resources are expensive and limited therefore, it is necessary to use and distribute them in an efficient way in order to optimize their use. Furthermore, the areas subject to wildfires can be spread out and distant, and there are several types of resources that can be needed depending on the situation. Coordination of resources is therefore crucial to effectively suppress wildfire emergencies. Resource management is not handled in any way by either the ICS or the existing software.

Difficulty in detecting wildfires.

In order to minimize the damage made by wildfires, Firefighter Corps need to promptly respond to these emergencies. This heavily relies on how quickly wildfires are detected and subsequently Corps are alerted. Currently most Corps rely on visual detection of fires by traveling through historical high risk areas ⁵. An exceptional case occurs in a specific region in Colombia, Aburra Valley, where the SIATA system uses sensors placed around the valley to measure different environmental variables, and sends alerts to the firefighter corps when needed ⁶. A big issue with this approach is the sole reliance on SIATA to do this tasks, a failure on their part could hinder the corps in being alerted.

1.3 Stakeholder Analysis

To properly design a system that tackles the targeted challenges, it is necessary to understand the needs of everyone involved. Using stakeholder analysis we derive usecases , scenarios and requirements of the system. The main stakeholders in our case, are presented in the following diagram:

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Manage Closely: These stakeholders are our main focus, since they will be the main users of the software. The Incident Command Officer (ICO), who is typically a Firefighter Captain or Commander, directs operations on-site and has the authority to request additional resources. Similarly, the Resource Manager, manages resource requests . Both these stakeholders play crucial roles, and ensuring their needs are met is essential for the system's success.

Keep Satisfied: Colombian Government: The government, as a stakeholder in the system, holds significant power due to its authority, jurisdiction, and control over policies and resources related to wildfire management. However, its interest in the operational details of the system may be relatively low compared to other stakeholders.

Keep Informed: We must keep these groups informed throughout the software development process: Incident Responders are the actors directly engaged in fire suppression efforts. Emergency services, including police, medical professionals, and other responders, play vital roles in coordinating emergency response efforts, although their specific involvement may vary. Developers have the technical expertise to influence the system's design and functionality to meet the objectives. Additionally, Data Providers, such as sensor mainframes, offer valuable data that aids in wildfire detection. Keeping these stakeholders informed ensures that the system meets the diverse needs of all involved parties.

Monitor: Media outlets, although their influence on system operations is limited, maintain an observational role. It's important to maintain communication with the media to ensure accurate reporting. Resource suppliers engage primarily in transactional interactions, providing essential resources for emergency response efforts. Monitoring their activities ensures timely access to necessary resources, optimizing emergency response efforts.

1.4 Ethical Considerations

Before designing a system, it is necessary to consider its ethical impacts. We found three main sources of concern:

Civilian population

The main objective of designing this system is to minimize any harm the civilian population may endure. To do so, it is necessary that the system is reliable and that it is an useful tool for firefighter corps to use in the handling of emergencies. The consequences for civilians can, in the worst case scenario, be fatal. Therefore, the system should not perpetuate any bias in resource management or hinder/delay the Firefighter Corps in any way. Additionally, the data sources the system gets the information from, should be reliable and notify of wildfires with no false positives or negatives.

Firefighters

The main ethical concern related to the firefighters is to keep in mind that they are still people even though the system allows to handle them as resources. For this reason, it must be essential that resource managers ensure that firefighters that are sent to handle an emergency are not overly overworked (eg. sending a firefighter to handle an emergency when they were just closing another one). Also, during the handling of the emergency, the ICO must be able to keep track of the amount of work that's being done by the firefighters under his command, so they won't get too overworked, specially since their working conditions are extremely dangerous and need to be in full capacity to minimize the risk. In other words, the system should account for human resources and their rights as personnel.

Environment

The concern is to mitigate the potential indirect environmental impact of this system. This impact may arise when dispatching resources to an Incident Command Officer (ICO) during emergencies in remote areas, where the absence of proper roads necessitates vehicles to forge paths wherever feasible to ensure resource delivery. Additionally, the system should address the environmental implications of resource allocation and coordination. Distributing all resources nationwide could result in environmental harm due to increased carbon emissions.

1.5 Sources of Ambiguity

To ensure a robust system design, it's vital to address and resolve ambiguity before proceeding to solution design. Here are some key areas where ambiguity needs to be tackled:

Data Sources: IoT and sensor data may vary in format and frequency of measurement. Determining which sensors and data sources our system will utilize requires clarity. Data sources should be reliable in performance and data needs to be accurate. To clear out this ambiguity, this project's focus will not comprehend the data sources in it self, but rather assume the presence of existing data sources. The systems focus is the compatibility with several different data sources.

Understanding Colombian Government Systems: Limited insights into government systems hinder tailoring efforts until official agreements are made. Uncertainty exists regarding current processes for collaboration and resource sharing. A solution is needed that can adapt to existing databases and streamline integration.

Coordination and Collaboration: Cooperation and support from various sections and partner organizations are essential. The system should be user-friendly such that collaboration will be easy. By addressing this ambiguity, we lay a solid foundation for designing a system that effectively meets the needs of stakeholders and operates smoothly within the Colombian context.

System's goal and solution: The scope of managing wildfires is huge. There are numerous factors, both human, machine and environmental. To be able to propose a solution for a system, the team should have a clear, concise and common understanding of what the system is trying to solve. The system cannot address the enormous scope of the problem at hand hence, we created a list of requirements appendix to help the team stay focused, aligned and effective in development process.

Explanation of terms: For the team, and who ever is interested in the projects it is important to have a clear understanding of what we mean with domain specific terminology. These are words or phrases that can be general, used in different manner or vague. To prevent problems or misunderstanding arising due to this we have defined the most ambiguous terms used by the project:

• Firefighter Corps: Refers to the organized group of firefighters responsible for combating wildfires and managing emergency situations related to wildfires.
• Incident Command Officer (ICO): A designated officer within the Firefighter Corps who assumes command and control responsibilities at the scene of a wildfire emergency. The ICO is typically a senior-ranking firefighter tasked with directing firefighting efforts, making critical decisions, coordinating resources, and ensuring the safety and effectiveness of response operations.
• Resource Manager: Entity responsible for managing and coordinating the allocation of resources needed to combat wildfires. This role involves assessing resource requirements, organizing available resources, responding to resource requests from Incident Command Officers (ICOs), and ensuring efficient utilization of resources during firefighting operations.
• Users: Resource Managers and Incident Command Officers (ICO).
• Personnel: FireFighters and ICO's.
• Resources: Personnels and equipment used for firefighting.
• Base camp: Designates a central location established by firefighters at or near the scene of a wildfire emergency. The base camp serves as a logistical hub for coordinating firefighting operations, managing resources, providing support services to personnel, and facilitating communication between responders. Base camps can be both permanent and temperate.
• Resource Requests: Requests made by Incident Command Officers (ICOs) to Resource Managers for specific resources needed to address wildfire emergencies. These requests typically include equipment, personnel, supplies, or other resources necessary for firefighting operations.
• Dispatch: Allocate resources to be used for emergency within one base, marking the resources as unavailable

2. Solution Design

2.1 Proposed Solution and Benefits

The proposed solution envisions a resource management system specifically designed for firefighters in the handling of wildfire emergencies. This solution provides the following benefits:

• Having user roles for different user permissions and access. Ensuring safe and reliant use of systems.
• An active record of available and non available resources for better resource management.
• Analyzing tool to support allocation of resources in an effective and environmental way
• Retrieve information from different sources to detect and alarm about wildfires.

This system aims to streamline coordination between active firefighters and the emergency command centers, gather data from multiple sources to enhance emergency detection and response, and efficiently manage both human and material resources.

As mentioned before, to be able to align the development within a team there should be a clear and common understanding of the systems goal on a functional level. To minimize ambiguity the team has taken advantage of the analysis of the existing system and stakeholders to define requirements using MoSCoW prioritization, see Appendix. To further understand the users point of view, user actions our systems supports are defined from these requirements and visualized in the use case diagram below.

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2.2 Quality Attributes

We derived quality attributes for the system based on the defined requirements and stakeholder needs. Based on that we define the desirable qualities of the system further categorized into internal and external attributes. We also identified some risks and recommendations in Appendix.

Internal Quality Attributes:

1. Maintainability: is prioritized for stakeholders, like developers, who require informed updates. Our focus is on ensuring that our low-level code is designed in a manner that allows for easy testing, modification, and independent reuse.

2. Testability: This remains a priority for developers. Our approach will involve adopting modular and domain-driven design principles to facilitate effective testing of the codebase.

External Quality Attributes:

1. Scalability: This is essential for stakeholders using the system and with high interest. Our system is designed to handle increased workloads without sacrificing performance as the organization's wildfire management needs grow over time.

2. Performance: The system should perform efficiently, with fast response times and minimal latency, to support time-sensitive decision-making and resource allocation. This is crucial for stakeholders like ICO's and resource managers during emergency situations.

3. Security: The system should prioritise the security of sensitive data, ensuring that only authorized users have access to certain information and that communication channels are encrypted to protect against unauthorized access.This is primarily important for the Colombian government.

2.3 Scenarios

After analysing stakeholders and defining requirements of the systems, we can use this information to prepare user scenarios. Scenarios lets us envision the usage of the proposed solution. This contributes to understanding the domain, but also a valuable resource for supporting the architectural design process, as it can reveal context and dependencies within the system. Next up is an overview of the use case scenarios for the system. The complete definition of each scenario is in the Appendix at the end of this document.

Overview of Scenarios

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• UC1 An User logs in to the system: either a Resource Manager or an ICO wants to log in to the system.
• UC2 An ICO sets up a Command Post/Base Camp: upon detection of a emergency and ICO arrives to scene, they want to set up a base camp to handle the emergency.
• UC3 An ICO requests resources to a Resource Manager: when needed, an ICO can request resources to be delivered to the current base camp.
• UC4 An ICO modifies a resource request: after sending a resource request, in case they need to adjust resources ordered or delete the request.
• UC5 An ICO closes the current Command Post/Base Camp: once an emergency is contained, an ICO can close the current base camp, as it is not needed any more.
• UC6 A Resource Manager processes requests from ICOs: a Resource Manager can evaluate resource requests sent by ICOs.
• UC7 An ICO assigns a task to a Firefighter: an ICO can assign a task to a firefighter under their command to complete during an emergency.
• UC8 An ICO marks a task as completed: once a firefighter completes an assigned task, the ICO can mark it as completed to free up the firefighter.
• UC9 An ICO updates the status of a wildfire: an ICO can update the status of a wildfire they are currently managing.

2.4 Initial concept

{{}} Below, we outline our initial architectural concepts, informed by our domain analysis. To explain the idea and concept behind this post, we provide a visual high-level overview of the system's external dependencies and interactions, in the form of a context diagram. BlazeGuard is tailored to Colombia and aims to coordinate with various external systems, including the NASA API, LookOut Wildfire Detection Service, LookOutCam app and SIATA.

Technical dependencies

• SIATA: Provides a comprehensive system for the detection and monitoring of environmental variables in Colombia's Aburrá Valley. The data includes information on air quality, weather conditions, and other environmental factors relevant to wildfire risk assessment. Integrating with SIATA, gives access to real-time environmental data.
• NASA API/FIRMS: An NASA API that offers daily global fire data, including data for Colombia. The data includes satellite-based fire detections, active fire locations, and fire intensity measurements. By leveraging the FIRMS API, the wildfire resource coordination system can access daily reports on active wildfires and their locations across Colombia.
• LookOut wildfire detection service: This is a distributer of surveillance cameras to detect wildfires. These give our system hourly reports based on camera surveillance.
• LookOutCam App: This is an application allowing users to report fires, detected smoke or other signs of wildfire they might discover. By making BlazeGuard integrable with LookOutCam our systems supports detection of fire that cannot be done by sensors, or that might be detected by humans before IoT devices.

Organizational dependencies

• The systems relies on the working forces within wildfire (see Stakeholders) incorporating our system for coordination, allocation and status update of resources.
• Responsible entities should provide the software and training to all users.
• We assume that incoming external aid will be reported through APC, Agencia Presidencial de Cooperacion Internacional, therefore, no changes to the organizational dependencies from the system used in Colombia today.

For the next iteration of development of BlazeGuard, we need to have an understanding of how the system works, not only the high-level context it is in ( the context view). As the problem description explains, the system relies on two different user types, resource manager and regular user (ICO). The reason for this it to allow different actions with authorization. Functionality is dependent on user type. The users interact with the system through a web application, which is dependent on the data from the sensor mainframe and location services. The service API's provide CRUD features.

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The Domain Model below captures the essential entities, attributes, relationships, and behaviors relevant to the domain, providing a structured framework for understanding and discussing the problem at hand. In our model we have the following relationships and behaviors for the entities.

• The base has an ICO personnel and equipment assigned to it.
• Each equipment requires skill to run.
• Each personnel has a rank(military ranks) and tasks assigned to them.
• Each personnel has status available/non-available to dispatch associated with them.
• Users are defined as ICO and resource managers with admin and non admin user types respectively.
• All personnel can view wildfire details , sensor data and post incident details on the dashboard.

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3. Proposed Roadmap

We have divided our roadmap into 4 phases as illustrated below, we intend to follow this plan for our system. This is partly inspired by aim42's software improvement phases. We understand and evaluate the system, then implement the solution and further improve and optimize the system. This iterative cycle aligns stakeholder requirements, aids developers in strategic planning, and guides project development to ensure adaptability to change.

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4. Pricing Model

BlazeGuard's pricing model is structured around our mission to safeguarding Colombia's wilderness and communities from the destructive force of wildfires. Recognizing the essential nature of our mission, we prioritize sustainability over profit. Hence, we propose a Recurring Revenue Model designed to ensure the continuous support and enhancement of our wildfire detection and management system. Under this model, we request an annual payment from the the government or beneficiaries, tailored to cover the costs of maintaining the software and providing ongoing support.

Architecting the Solution

In order to aid Colombia’s firefighters in containing the increasing amount of wildfires that occur due to 'El Niño' phenomenon ⁷, we designed BlazeGuard, a wildfire alert and resource management system. In this document we will explain the process of designing BlazeGuard, by explaining its architecture through different views of the system, important architectural decisions made, and a Proof of Concept to show the strengths of the decisions made for the system.

A complete overview of this document is as follows:

• Introduction
• Solution Strategy
• Building Block View
• Runtime View
• Deployment View
• Architectural Decisions
• Exploring the design choice
• Proof of Concept

1. Introduction

During problem analysis step ⁸, we identified some critical aspects of the system, it’s environment and the users. Before diving into the architectural design, we will remind the reader of the key points from the problem analysis. Below, you will find the use-case diagram originally presented in our Blog post 1, outlining the functional requirements of BlazeGuard. Through a stakeholder analysis we identified high-priority expectations of BlazeGuard and the corresponding software architecture requirements, all of which are explored in the next section.

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After outlining the functional requirements of the system through the use case diagram, the next step is to delve into the structural aspect of the system by representing its domain model. This transition is facilitated through the creation of an Entity-Relationship (ER) diagram, which captures the essential entities and their relationships within the system.

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Our domain holds multiple types of Users, mapped as Personnel. Each personnel is assigned a rank and belong to a certain Base. Personnel and Equipments together form the resources that are available for firefighting emergencies, and Equipments are mapped to Personnel through Skill. For ICO to keep track of what Personnel entities are doing we created a Task Mappings relation, that map Tasks to Users. Moreover, to keep track of availability of Equipments and Personnel we have Status.Other independent tables are Post Incident Details, that is used to log firefighting reports, and Sensor Data, which is a Time series database. The microservice boundaries are inspired from the domain discussed, hence supporting our Domain Driven Design principle.

2. Solution Strategy

Here we propose the solution strategy we followed for BlazeGuard's design. We aim to implement robust architectural paradigms, follow best practices in software design, and prioritize code quality and maintainability. BlazeGuard aims to deliver a robust solution that meets the needs of stakeholders. The solution approaches, derived from the quality goals, are summarized in the table below.

Quality Goals

Key Quality Goal	Scenario	Solution Approach
Scalability	High workload during wildfire emergencies	Microservices Architecture
Testability	System should be testable and any changes in the system are flagged quickly	Test Driven Development
Resilience	System should not lose critical information, in case of downtime or service failure	Event-Driven Communication
Maintainability	Easy to understand, modularized components in codebase and comprehensive documentation	Clean Code Architecture, SOLID Principles

Solution approaches are motivated by the desire to build a scalable, testable, resilient, and maintainable system, our key quality goals. These are identified as the most significant quality attributes from the problem analysis. The table below provides a summary of how they were derived from our stakeholder analysis. We will be elaborating on and reference the table further in this section.

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By keeping these quality goals in mind, readers can better grasp the reasoning behind our chosen solutions and how they align with the project's overarching objectives.

We will now elaborate on our solution approaches which can be divided into two categories: Technology Decisions, and Design Principles and Guidelines.

Technology Decisions

Microservices: allows for the decomposition of the system into smaller, loosely coupled, manageable services that can be developed, deployed, and scaled independently ⁵. Each microservice is responsible for a specific domain or functionality within the BlazeGuard ecosystem, this enables the system to scale horizontally by distributing the workload across the independently deployable services. The specific services for BlazeGuard are defined and explained in section 3, Building Block View.

Event-driven architecture: The communication between microservices is determined by how events control the flow of information exchange and interaction among components. Events signify incidents within the system, that trigger actions across services. With Event-Driven architecture, BlazeGuard ensures efficient collaboration among its components without tight dependencies ⁹. Utilizing Kafka as the event bus, BlazeGuard manages communication between its microservices.

Design Principles and Guidelines

Clean Code Architecture: ensures that the system’s code base remains modular, readable, and maintainable ¹⁰. This approach promotes separation of concerns, making it easier to understand and modify the code as the system evolves. By adhering to these principles, developers can navigate the codebase more efficiently, reducing the risk of introducing errors or unintended side effects during maintenance or updates.

SOLID Principles: SOLID principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) guides the design of software components, fostering code that is flexible, robust, and extensible ¹⁰. Dependency inversion and interface segregation principles help minimize dependencies between modules, reducing coupling and enhancing modularity. By following these principles, we aim to reduce code complexity and minimize dependencies between modules, enhancing the system’s overall stability.

Test Driven Principles: Ensuring robust testing practices is essential to validate the system’s functionality and reliability. Test-Driven Development (TDD) promotes testability by requiring tests to be written before code implementation, fostering a comprehensive suite of automated tests that validate the system’s behavior ¹¹.

Now, we will explain the quality attribute table introduced earlier, highlighting which approaches support each quality goal (italicized) and meet the corresponding stakeholder expectations from the Detailed Quality Attributes table{:target="_blank"} (marked with [i]).

Scalability Microservices architecture and event-driven paradigm : As we have seen in Technological Decisions, Microservices and Event Driven architecture will allow BlazeGuard to handle sudden spikes in activity, that is periods of high wildfire activity, effectively meeting several stakeholders needs [1].

Testability The Test Driven Principles in conjunction with the Microservice Event-Driven architecture, will allow the developers to write tests for each of the systems components in isolation. Through unit testing, integration testing, and end-to-end testing the expected behavior of the system can be verified for each component before it integrates into the larger system, ensuring that all parts function correctly. BlazeGuard seeks to satisfy the developers need for an understandable and an effective code structure [8], the ICO's need for a reliable system [4] and the incident responders need for a safe work environment [7].

Resilience BlazeGuard adopts an event-driven architecture combined with microservices. This architectural choice enables the system to withstand and recover from failures gracefully. Additionally, event-driven architecture facilitates the implementation of robust error handling mechanisms, such as retries, circuit breakers, and dead-letter queues, which enhance the system's resilience to failures. By prioritizing resilience, BlazeGuard aims to meet the needs of stakeholders, so that critical information is not lost [2].

Maintainability Emphasis on Clean Code architecture and adherence to SOLID principles enhances maintainability of the system. By adhering to these principles, the system can accommodate evolving requirements and needs without requiring extensive refactoring or redesign. Together these solutions solve the Resource managers and ICO's need for an adaptive system [3], [4], [5], [6] while also making it easy for developers to understand and work on the existing as well as new features, faster [9].

Hopefully, these decisions serve as an understanding for developers , stakeholders and architects alike. These decisions are, the cornerstones upon which the architecture of BlazeGuard is built. They provide a direction and rationale for the subsequent system implementation.

3. Building Block View

To further understand the system and architecture in detail, we provide visualization of five different levels of abstraction:

1. Context view: Context and environment the system exists in, external dependencies
2. Container view: Overall architecture of the entire system
3. Component view: Detailed overview of container
   • BlazeGuards microservices
   • API Pattern
4. Class view: Detailed overview of each class within the components.
5. Code view: Detailed description of the class.

Context view

A context diagram offers a high-level view of a system’s environment, depicting its boundaries and interactions with external entities. It serves as a foundational element for understanding a system’s functionality within its operational context.

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The model depicts how BlazeGuard fits into the existing environment, with the external dependencies that detect wildfires at different report frequencies. These dependencies include the NASA API, LookOut Wildfire, LookOut Cam, and SIATA ^{10 11 12}. Keeping in mind the quality attributes, especially maintainability, BlazeGuard should be adaptive to new data sources.

Container View

Now that we understand how BlazeGuard fits in the environment, let us focus on the system boundary. The following figure shows a high level view of the entire system that will operate as a unit.

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In the figure, it is shown how the Users, Resource Managers and ICOs, access the system through a Website that is a Single Page Application (SPA). This SPA, developed using JavaScript and Vue is the main access point for all the app's features. It communicates with the backend, an API Application built with Java, TypeScript, and Python, facilitating services through secure HTTPS/JSON protocols. This API Application is the gateway to both external sensor data sourced from the Mainframe Sensor System and internal databases that include time-series and SQL databases. Through this architecture, BlazeGuard ensures efficient data retrieval and manipulation, supporting critical wildfire detection and reporting functions.

Component View

This view depicts the major building blocks of the system and the interactions among them, showcasing the components within our system.

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In the model, each component, or microservice, is designed around a distinct domain, adhering to the principles of Domain-Driven Design (DDD). This approach helps aligning the system with the business needs, facilitating a more intuitive development and maintenance process. By employing DDD, we define microservice as the domain's subdomain. This results in each microservice managing its distinct domain logic. This enhances system modularity and maintainability, supporting our architectural goal of creating loosely coupled components. The Kafka Client, which functions as the event bus, is used for the transmission of messages among the most critical services like the fire locator service, and the resources request and request management services.

Now we will be summarize each microservice:

API Gateway: This gateway serves as the secure entry point for users, directing requests to the appropriate microservices with efficiency and security.

Dispatcher Service: This service coordinates the allocation and dispatch of firefighting resources to incident sites, ensuring a rapid response to wildfire outbreaks.

Location Service: Acting as the system’s navigator, this service provides precise location data crucial for mapping the spread and intensity of wildfires.

Fire Locator Service: Constantly analyzing sensor data, this service is on the lookout for anomalies that may indicate a wildfire, serving as an early warning system.

Request Resource Service: This service handles the request of resources from the ICOs during a wildfire fighting operation.

Post-Incident Recovery Service: Focused on learning and adaptation, this service facilitates post-incident assertion to aid in recovery and prepare for future incidents.

Resource Management Service: Overseeing the distribution of resources, this service allows for allocating resources to where they are needed.

Alert System: This system ensures that all relevant parties receive timely notifications about wildfire detections and resource request and deployments, keeping everyone informed and ready to act.

We chose Java Spring boot as our development framework. For databases, we opted for a combination of SQL and NoSQL time series databases. Specifically, we selected MongoDB for the Fire Locator Service due to its NoSQL nature and time series capabilities, while we settled on MySQL for all other services.

API Pattern

For interaction amongst the services we decided to go with a data-oriented approach to ensure clarity and ease of use. To address the inherent linkage between services and their functionalities, the concept of a Solution-Internal API¹³ was used. This architectural pattern restricts access to APIs exclusively to internal components within Blazeguard ecosystem. By logically decomposing the application into distinct components, each equipped with its own set of APIs, the system ensures that only authorized services within the application backend can interact with designated functionalities. This approach enhances security and encapsulation within Blazeguard Wildfire Resource Management System, safeguarding sensitive data communication between internal components.

Classes View

The components we talked about are now turned into code artifacts. In each service, we define its domain and use cases, which interact with its own interface and data layer. We create each service in a particular way, which we will explain in the next section. Looking at this view, we noticed it's quite complex, which might make it harder for the team to communicate as the project grows.

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Code View

The Code View diagram provides a detailed structural overview of the services that follow the Clean Code Architecture pattern. At its core, the diagram features the domain layer, which is fundamental to the application. This layer houses the business logic and essential entities that drive the application's primary functions through various use cases. The separation of data layer allows us to keep our system extensible to any type of data source without changing any line of code in the domain or interface layers.

Surrounding the core domain layer are two critical interface layers: the external interfaces and the data layer. The external interfaces are comprised of controllers or adapters that manage incoming requests and output data to users or external systems. The data layer, on the other hand, handles interactions with the database.

The domain layer serves as an intermediary between the data layer and external interfaces, orchestrating the execution of business logic through use cases.

Dependencies between layers adhere to the Dependency Inversion Principle, with higher-level modules depending on abstractions rather than concrete implementations. This modular structure promotes separation of concerns, facilitates testability, and enables flexibility and maintainability throughout the software system. We arrived to this decision by following Conway’s Law¹⁴ which is essentially the observation that the architectures of software systems look remarkably similar to the organization of the development team that built it.

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4. Runtime view

To understand how the building blocks of the system behave, we’ve decided to depict two sceranios in our sequence diagram.

1. Begins with an event, triggered by the Fire Locator Service. This event initiates a notification process directed towards the Incident Command Officer (ICO). Subsequently, the ICO may decide to engage the Dispatcher Service to allocate resources to their designated base.
2. Extends the narrative, illustrating situations where the ICO might require additional resources. In such cases, a Resource Manager is involved to review and approve the request for transferring resources among bases.

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It's imperative to note that the services deployed in our system operate under high emergency conditions, where any downtime could potentially result in severe consequences, including ecological damage and possibly loss of life. Therefore, we've opted for a microservices with event driven architecture to ensure resilience and reliability.

5. Deployment View

The deployment diagram illustrates the system, designed for incident response, featuring a network of components and their interconnections. At its core are the Users, initiating requests and engaging with the system through various workstations, including an ICO workstation and an Resource Manager(RM) workstation. Anchoring the system are multiple servers, comprising a message handler server (where the Kafka client is hosted), a database server (which holds the complete inventory of the corps and other important information), and a final server that hosts services such as the fire detection or the alert system. External entities, labeled as Third Parties, contribute data related to wildfire detection to the fire locator service. The flow of data starts with Requests originating from user Workstations, funneled to the main server, which orchestrates interactions with all of its components.

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The Message Handler facilitates message routing, while the Base Camp serves as a central coordination hub. Kafka supports real-time messaging, FIRMS provides satellite data of active hotspots, sourced from NASA, and LookOut Cam provides direct fire detection via live visualization using cameras. SIATA aids in retrieving a more precise and frequent measurement of meteorological data. The Resource Manager Service oversees resource allocation during incidents, while the Alert System disseminates critical information. Post-Incident Recovery Service assists in restoring normalcy, and databases store configuration and inventory data. The Fire Locator Service pinpoints fire locations. Finally, it is important to note that the third parties services will likely expand in the future, as more systems get deployed throughout Colombia.

6. Architecture Decisions

In this section, we delve into a significant architectural decision we have made: adopting a Microservices Event-Driven Architecture, our hybrid approach. We aim to provide a detailed explanation of our rationale, explore alternative options, conduct a thorough analysis of their tradeoffs, and ultimately justify our chosen design approach.

Exploring the design choice: Microservices and Event-Driven architecture

Layered Architecture

Layered Architecture is a design pattern that organizes software components into distinct layers, each responsible for a specific set of functionalities ¹⁵. These layers are arranged hierarchically, with each layer building upon the functionalities provided by the layer beneath it. Layers in Layered Architecture:

• Presentation layer: The topmost layer of the architecture, responsible for handling user interaction and presenting information to users. This layer typically includes user interfaces, such as web interfaces, mobile apps, or desktop applications.
• Application layer: The middle layer that contains the core business logic and application-specific functionalities. This layer orchestrates the flow of data and processes within the system, handling business rules, validations, and workflow logic.
• Data Access layer: The bottommost layer responsible for interacting with the data storage systems, such as databases or external services. This layer abstracts the details of data persistence and retrieval, providing a unified interface for accessing and manipulating data

Even though it sounds seem very organized it still has some drawbacks, namely:

• Communication overhead between layers can impact performance.
• Tight coupling risks if layer boundaries aren’t well-defined.
• May become overly complex with numerous layers.

Monolithic Architecture

Monolithic Architecture is a traditional approach where the entire application is developed and deployed as a single, cohesive unit ¹⁶. It lacks the modularity and scalability advantages of Microservices. While less common now, it’s still seen in some legacy systems. The fact that there are many Legacy systems still using this we conclude that it still delivers value but with some drawbacks:

• Limited scalability, as the entire application must be scaled.
• Difficulty in maintaining and updating due to tight coupling.
• Deployment of updates can be riskier.

Microkernel Architecture

Microkernel Architecture, also known as ”plugin architecture,” separates the core system from extended functionalities, enabling flexibility and customization ¹⁷. However, it may introduce complexity and performance overhead. This architecture seemed a good option for our usecase but we had to drop it since we were not sure what external sensor mainframe our system might integrate in future. With this we identified more drawbacks:

• Communication between core and plugins can introduce overhead.
• Plugins may have dependencies on specific core versions.
• Managing interactions between core and plugins can become complex.

Peer-to-Peer Architecture

In the traditional client-server model, a central server is the main hub that provides services to many client devices. This model works well, but it’s very centralized, meaning the server is the most important part of the network. On the other hand, Peer-to-Peer (P2P) architecture changes things by breaking away from this centralized setup. Instead, it promotes a more equal model where each node, or ’peer’, is just as important as the others in the network ¹⁸. In a P2P network, every peer has a double role – it acts as both a client and a server. This means that peers can directly communicate with each other and share things like processing power, storage space, and network capacity without relying on a central server. This decentralization is at the heart of P2P architecture, giving it some special advantages and making it a great option for lots of different applications. Though this brings in some inherent advantages like robustness, scalability and efficiency, it comes with it’s own set of drawbacks:

• Security concerns due to direct connections between nodes.
• Scalability challenges in very large networks.
• Lack of central control can lead to coordination issues

With all the above knowledge we went ahead and did a tradeoff analysis of five architectures, four explained above and one is our hybrid Microservice Event Driven Architecture.

Trade-off Analysis

Here we perform a tradeoff analysis,

Architecture Pattern	Performance	Scalability	Testability	Ease of deployment	Easy of development
Layered Pattern	Low	Low	High	High	High
Monolithic Pattern	Variable	Low	High	Low	High
Microkernel Pattern	Low	High	High	High	High
Peer-2-Peer Pattern	High	High	High	High	High
Microservice Event Driven	High	High	High	High	High

For the layered architecture's case, performance could be low due to overhead of multiple layers. Scalability might be constrained by layer dependencies. Although testability is good since layered architecture aids unit testing.

For the monolithic architecture's case, we believe performance could be high since direct function call reduces network call overhead. Scaling would be difficult since it requires duplicating the entire monolith architecture. Testability would be high as components can be tested within the monolith.

When it comes to the microkernel architecture, performance is said to be low due to indirection overhead. Scalability is high due to plug and play extensions which also extends to ease of testing as core and extension can be tested easily.

A Peer-to-Peer (P2P) system is often considered optimal across all criteria for several reasons: distributed computing capabilities, the ability to add any number of nodes, the ability to test peers individually, and the dynamic joining and leaving of peers from the network, among others.

For Microservice Event Driven architecture, performance is high due to distributed nature and scalable services. Testing is simplified with independent microservices, enhancing test coverage. Deployment is agile with independent services, minimizing downtime. Development benefits from modular design and rapid iterations.

In choosing the Microservice Event-Driven architecture, we're drawn to its many advantages and adaptability. This architecture relies on events or messages to connect different parts of the application, triggered by changes in its state. It offers several benefits: Firstly, it enables easy communication between services, allowing us to add or remove them as needed without hassle. Secondly, it allows us to introduce new services without disturbing the existing ones, making it simpler to add new features. Thirdly, it reduces the risk of failure by allowing services to communicate asynchronously. Lastly, it ensures swift communication between services, enabling real-time updates and interactions. These advantages are aligned with our project's needs, making Microservice Event-Driven architecture the ideal choice for ensuring scalability, flexibility, resilience, and speed in our system's design.

7. Proof of Concept

Now that we've explained and justified our decision-making process, it's time to move on to some proof of concepts (PoC) of the system. Our PoCs are a simplified, experimental version of components of the final system, aimed at demonstrating BlazeGuards resilience and maintainability. Ultimately, a successful PoC should instill confidence in the viability of the idea and help guide future development and investment decisions.

We performed two experiments namely:

• Code Maintainability: using Springboot with clean architecture.
• Resilience: using Kafka event bus.

Given that no similar system has been deployed in Colombia, the ability to develop and integrate the system quickly and continuously will be crucial in ensuring its long-term serviceability. We chose not to demonstrate common metrics like scalability and fault tolerance since these are inherent to common architectures like Microservices.

1. Code Maintainability:

This experiment aims to evaluate the maintainability of our codebase. To do this, we will analyze code readability, adherence to coding standards, and ease of understanding and modifying the code. We aim to ensure that our codebase remains maintainable and extensible over time, by adherence to clean coding practices and SOLID principles. This experiment showcases a practice which introduce an overhead of scaffolding and writing contracts within the code. However, while it may appear redundant for small-scale projects, it plays a vital role in ensuring the maintainability and extensibility of large-scale projects over time, such as BlazeGuard.

Spring Boot stands out as the most known framework for Java-based web applications, emphasizing simplicity in application setup with its "just run" approach. Its architecture reflects this simplicity, structured in layers with hierarchical communication between them. At the core of Spring Boot's architecture lies its simplified design as shown in the diagram below, characterized by layered communication. Notably, the Repository and Data Transfer Objects (DTOs) layer introduces additional dependencies, particularly impacting the Model layer. Additionally, all layers rely on framework code, rendering them susceptible to changes in the its interface. While these issues may seem insignificant in smaller projects with fewer developers, they escalate with project scale and complexity. As projects grow, these dependencies result in more substantial and costly code modifications.

{{}}

The simple architecture is implemented with following folder structure: {{}}

Methodology: Addressing the problem outlined above, we propose a solution by applying Clean Code Architecture, which is domain-centric and aligns with our objective of adopting a Domain-Driven Design approach. This architecture is structured with defined communication protocols between its layers to ensure clarity and maintainability in the system's evolution. Spring Boot combined with Clean Architecture principles, necessitates isolating domain logic from framework details. This involves utilizing gateways and interfaces for dependency inversion within layers.

The proposed architecture consists of three layers: Infrastructure, Use Case, and Entity, with a strict hierarchy ensuring inner layers remain unaware of outer layers. The Infrastructure layer integrates framework-dependent code such as controllers, JPA repositories, and domain model schemas. This decision aims to bridge conventional Clean Architecture layers, enhancing clarity. The subsequent layers operate independently from framework code. The Use Case layer houses system logic and DTO contracts for data exchange between application layers. The Entity layer encompasses domain models and contracts for database interaction, ensuring consistency in data manipulation. {{}}

The Clean Architecture is implemented with the following folder structure: {{}}

Metrics: We used SonarQube¹⁹ for measuring metrics for our POC. SonarQube helps make applications last longer by simplifying code, removing duplicates, and preventing bugs. It promotes clean architecture and more unit tests, making software easier to maintain and adapt to changes.

Readability and Maintainability:

SonarQube use clean code approach to measure the readability and maintainability²⁰. {{}}

We implemented the same business logic in two ways, one using the Simple architecture, rms-simple and other using the clean architecture, rms-clean-code-arch. It's evident from the readings in the figure above that rms-clean-code-arch have less reliability and maintainability issues. Although this came with a cost of code duplication due to redundant code needed to make framework work with the framework free domain layer.

Code Cognitive Complexity

This defines how hard it is to understand the code's control flow²¹. From the figures below it is evident from metrics that clean code²² did cause a decreased cognitive complexity but had an increased cyclomatic complexity due to addition of code that facilitated contracts and constraints on communication amongst the layers. {{}} {{}}

2. Resilience, Shutting and resuming a service:

This experiment holds significant importance as certain services are crucial for wildfire management. Any service failure should gracefully fallback and recover to ensure uninterrupted operations. Through this experiment, we aim to illustrate the rationale behind incorporating Event-Driven Architecture into Microservices. We will intentionally shut down selected services subscribed to the Message Broker and then restart them after a period. We anticipate the restarted servers to resume receiving messages that were not yet consumed due to the earlier failure. We have implemented producer and consumer services for our system. The producer service collects data from the sensor mainframe and generates emergency alert messages. These alerts are then consumed by notification services subscribed to the 'Wildfire-Alert' topic. If we shut down the consumer service, the alert messages produced will queue up, awaiting consumption. Upon restarting the services, the queued messages are processed, and alerts are dispatched accordingly.

To follow or extend our proof of concept, you can refer to our repository ²³.

Appendix A: Use Cases

UC1 - An User logs in to the system.

Preconditions:

• The user is registered in the system.
• The user is in possession of their credentials.

Postconditions:

• The user successfully logs in the system

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an user to successfully log in the system:

{{}}

UC2 - An ICO sets up a Command Post/Base Camp.

Preconditions:

• The ICO is registered in the system
• The ICO is assigned to respond to the wildfire

Postconditions:

• Base camp is successfully set up

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to successfully set up a base camp to handle a wildfire emergency:

{{}}

UC3 - An ICO requests resources to a Resource Manager.

Preconditions:

• The ICO has a base camp setted up.

Postconditions:

• A request is successfully sent to the Resource Manager (RM)

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to send a resource request to the RM:

{{}}

UC4 - An ICO modifies a resource request.

Preconditions:

• The ICO has previously sent a resource request

Postconditions:

• The request is successfully modified in case it has not been dispatched yet.

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to modify a resource request they have already sent:

{{}}

UC5 - An ICO closes the current Command Post/Base Camp.

Preconditions:

• The ICO is assigned to a base camp.
• The wildfire emergency's status currently being handled has its status changed to contained/completed.

Postconditions:

• The base camp is successfully closed.

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to close the base camp they are assigned to:

{{}}

UC6 - A Resource Manager processes requests from ICOs.

Preconditions:

• The Resource Manager is logged into the system.

Postconditions:

• The resource request is handled.

Flow Diagram

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for a Resource Manager to handle a resource request from an ICO:

{{}}

UC7 - An ICO assigns a task to a Firefighter.

Preconditions:

• The ICO is logged in the system.
• The ICO has at least one firefighter currently assigned to the base camp.

Postconditions:

• The task is successfully assigned to the firefighter

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to assign a task to a firefighter:

{{}}

UC8 - An ICO marks a task as completed.

Preconditions:

• The ICO is logged in the system.
• The ICO has assigned a task to a firefighter in the basecamp.
• The firefighter has completed the task.

Postconditions:

• The task is successfully marked as completed, freeing the firefighter from it.

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to mark a task assigned to a firefighter in the base camp as completed:

{{}}

UC9 - An ICO updates the status of a wildfire.

Preconditions:

• The ICO is assigned to a base camp.

Postconditions:

• The status of the wildfire is successfully changed.

Flow Diagram:

The following diagram displays the flow of this use case. It clearly displays the steps that are to be followed for an ICO to change the status of a wildfire:

{{}}

Appendix B: Requirements

Functional Requirements:

To further be able to prioritize development, the team has divided the requirements into different severity levels (must, should, could, won't and non functional) for the project.

Must

• A user must login/logout
• A user must receive a notification when a wildfire is detected.
• A user must be able to view wildfire incident details like severity, containment status, location etc.
• A user must be able to view all base camps.
• An ICO must be able to see the inventory of resources currently at their base camp.
• An ICO must be able to view all basecamp locations.
• An ICO must be able to dispatch the resources of their own base camp in case of an incident.
• An ICO must be able to request resources to the resource manager.
• An ICO must be able to view which resources they are allocated.
• A resource manager must be able to dispatch the resources of all base camp in case of an incident.
• A resource manager must be able to log new resources in the inventory.
• A resource manager must be able to view resource requests from ICOs.
• A resource manager must be able to accept dispatch requests.
• A resource manager must be able to deny dispatch requests. A resource manager must be able to modify dispatch requests.(if 10 resources are requested , but only 8 are available, the resource manager must be able to approve 8).
• A resource manager must be able to view and track the inventory of total resources of the corps(including all allocated resources to all other base camps) based on availability and utilization in real time.
• A resource manager must be able to add new users to the system.

Should:

• A user should be able to access information on historical wildfire incidents.
• A user should be able to generate reports on past wildfire incidents, including details like location, size , duration and impact.
• A resource manager should be able to access historical data for resource allocation.
• An ICO should be able to document and track incident-related communications, decisions, and actions within the system for accountability and record-keeping purposes.
• An ICO should be able to generate incident reports summarizing key information, actions taken, and outcomes for post-incident analysis and documentation.
• An ICO should not be able to overwrite a resource manager

Could:

• A resource manager could give a reason for the denial/partial denial of a request.
• A resource manager could conduct resource allocation simulations within the system to optimize resource deployment strategies based on different scenarios.
• A resource manager could communicate with resource suppliers directly through the system to request additional resources.

Won't:

• A non-ICO user wont be able request resources
• An ICO wont be able to handle two separate base camp wildfire incidents simultaneously.

Non-Functional Requirements:

• The system will provide well documented RESTful API.
• The system will have a design that is easy to implement.
• The system will be designed using SOLID principles.
• The system will contain microservices architecture for modularity and scalability.
• The system will comply with interoperability standards and protocols established by relevant organizations like NIMS, ICS, EDXL.
• The system will provide security features for authentication , authorization and accountability using the identity service.
• The system should be able to integrate data for wildfire detection from multiple sources
• The system should have an intuitive user-friendly interface for users with varying level of familiarity with technical systems.
• The system should be interoperable with existing government databases, weather forecasting services and communication platforms for data exchange.
• Comprehensive documentation and technical support will be provided for the system to facilitate effective utilization.

Quality Attributes:

1. Maintainability:

   • Background: Developing maintainable code is crucial for the long-term sustainability of our software system. Without proper maintainability practices, the codebase can become difficult to manage and update, leading to increased technical debt and decreased developer productivity.
   • Risks Identified: The risk of poor maintainability includes longer development cycles, increased likelihood of introducing bugs during modifications, and difficulty in onboarding new developers to the project.
   • Recommendation: To address this risk, we recommend implementing modular design principles, clear documentation, and consistent coding standards to ensure that the codebase remains maintainable throughout its lifecycle.

2. Testability:

   • Background: Testability is essential for ensuring the reliability and stability of our software system. Without adequate testability measures, it becomes challenging to verify the correctness of the code and detect potential defects early in the development process.
   • Risks Identified: Inadequate testability can lead to increased regression issues, decreased software quality, and difficulties in achieving test coverage goals.
   • Recommendation: To mitigate these risks, we recommend implementing modular design patterns, dependency injection, and automated testing frameworks to improve the testability of our codebase.

3. Scalability:

   • Background: Scalability is essential for ensuring that our software system can accommodate growing user bases and data volumes without experiencing performance degradation or service disruptions.
   • Risks Identified: Risks associated with scalability limitations include decreased user satisfaction, increased downtime, and potential loss of business opportunities.
   • Recommendation: To mitigate these risks, we recommend adopting scalable architectures, distributed computing paradigms, and horizontal scaling strategies

Appendix C: Interview with Volunteer Firefighter

Interview video is present in the following url (spanish): https://youtu.be/M0NXRZvkQ9k The full transcript of the interview in english is present in the following document: https://docs.google.com/document/d/1HFL6Uxy1Oo1XIRbS0rddSTvBzY8dvc7OfmHIKStZ_6I/edit?usp=sharing

Note that due to the length of the interview, it was not practical to transcribe and translate it manually, so ChatGPT was used.

Footnotes

1. M. Rios. "Colombia declares a disaster due to wildfires as it calls for international help. CNN.
   https://edition.cnn.com/2024/01/25/americas/colombia-disaster-wildfires-el-nino-intl-latam/index.html. Last accessed March 25 2024. ↩

2. J. C. Granados. "Gobierno colombiano declara situación de desastre y calamidad en el país ante el grave impacto de incendios forestales". Mongbay. https://es.mongabay.com/2024/01/gobierno-colombiano-declara-situacion-de-desastre-y-calamidad-en-el-pais-ante-el-grave-impacto-de-incendios-forestales/ ↩

3. Interview with Volunteer Firefighter Nicolas Lastre. https://youtu.be/M0NXRZvkQ9k ↩

4. idc appdrones. "Operaciones de Emergencia: Sistema Comando de Incidentes". IDC. https://idc.apddrones.com/humanitario/operaciones-de-emergencia-sistema-comando-de-incidentes/#:~:text=El%20Sistema%20Comando%20de%20Incidentes%20es%20una%20herramienta%20de%20manejo,incidentes%20y%20manejo%20de%20eventos. Last accessed March 25 2024. ↩

5. Mircoservices https://aws.amazon.com/microservices/ ↩ ↩² ↩³

6. SIATA https://siata.gov.co/sitio_web/index.php/ ↩

7. Wildfire report https://edition.cnn.com/2024/01/25/americas/colombia-disaster-wildfires-el-nino-intl-latam/index.html ↩

8. Problem Analysis https://gitlab.ewi.tudelft.nl/in4315/2023-2024/desosa2024.gitlab.io/-/blob/master/content/projects/03-wildfires/posts/r1_problem_analysis.md?ref_type=heads ↩

9. Event Driven Architecture https://aws.amazon.com/event-driven-architecture/ ↩

10. SOLID Principles https://blog.cleancoder.com/uncle-bob/2020/10/18/Solid-Relevance.html ↩ ↩² ↩³

11. TDD Real World Example https://medium.com/@dees3g/a-guide-to-test-driven-development-tdd-with-real-world-examples-d92f7c801607 ↩ ↩²

12. NASA firm API https://firms.modaps.eosdis.nasa.gov/map/#d:24hrs;@0.0,0.0,3.0z ↩

13. Solution Internal API https://microservice-api-patterns.org/patterns/foundation/SolutionInternalAPI ↩

14. Conway's Law https://martinfowler.com/bliki/ConwaysLaw.html ↩

15. High assurance software architecture and design https://www-sciencedirect-com.tudelft.idm.oclc.org/science/article/pii/B9780323902403000151 ↩

16. Monolith Vs Microservice https://www.atlassian.com/microservices/microservices-architecture/microservices-vs-monolith ↩

17. Architecture Patterns https://www.oreilly.com/library/view/software-architecture-patterns/9781098134280/ch04.html ↩

18. Cognitive Complexity https://medium.com/@nikhiljain1203/peer-to-peer-architecture-a-deep-dive-into-the-future-of-networking-d0f07945dca5 https://www.sonarsource.com/resources/cognitive-complexity ↩

19. Sonarqube https://docs.sonarsource.com/sonarqube/latest/ ↩

20. Sonar Clean Code Approach https://docs.sonarsource.com/sonarqube/latest/user-guide/clean-as-you-code/ ↩

21. Sonarqube Cognitive Complexity ↩

22. Sonar Clean Code https://docs.sonarsource.com/sonarqube/latest/user-guide/clean-code/definition/ ↩

23. POC github repo https://gitlab.ewi.tudelft.nl/in4315/2023-2024/groups/team-3/ ↩