Architectural Kata Series
2nd problem: Hot Dog Stand Point-of-Sale (POS)
Last time, as part of our architectural kata series, we discussed building a testing software system and creating the best user experience. We discussed different subjects such as microservices, API gateway, and database structure. Check it out here.
The problem we are going to discuss today is HotDiggetyDog:
Considering the specifications and requirements for the Hot Diggety Dog point-of-sale system, we will begin an architectural kata to develop a solution that meets the project’s objectives.
The objective is to create a Point-of-Sale (POS) system that caters to hot dog stand operators who work in a dynamic and mobile environment. The system must enable approximately fifty stand operators to interact with thousands of customers through social media. Since operators work on the streets, the solution must be lightweight and more efficient than manual sales tracking processes. The aim is to develop a system that simplifies sales and inventory management, integrates with social media for customer engagement, and notifies potential customers of nearby hot dog stands.
Key features
Discounts and Sales Tracking
We will use unique identifiers for each sale, including timestamp and location data. We will apply discount logic at the point of purchase through the mobile app and aggregate sales data in the backend for analytics and reporting.
Inventory Updates and Management
To make sure we have efficient inventory management, ensuring real-time synchronization is essential. We can implement WebSocket or use Firebase to achieve real-time data synchronization between the mobile app used by operators and the inventory management staff.
Receiving timely notifications for low stock levels is essential to optimizing inventory management. To do this, we could use cloud functions that trigger notifications for inventory-management staff when stock levels for specific items fall below a threshold.
Social Media Integration
API Integration involves using social media platforms’ APIs( e.g.,Twitter Facebook) to automatically post updates about the hot dog stand’s location or promotions. However, it is essential to consider user privacy and platform limitations while implementing this strategy.
Geo-targeting could be an approach to delivering social media notifications to users within a certain radius of the hot dog stand. This technique utilizes location data to achieve this.
Exportable Data for Accounting
To ensure that the accounting software can easily use data from the system, it is important that the data can be exported in CSV or Excel formats. This can be achieved by implementing export functionality in the backend, which enables users to generate reports based on custom date ranges and metrics.
System Overview
To understand the architecture better, let’s imagine a process that starts from the mobile application used by hot dog vendors and flows through the API Gateway, which directs requests to the appropriate microservices. These microservices interact with the distributed database and caching layer to retrieve and store data. Serverless functions are triggered by specific events, such as changes in stock levels, and all operations are monitored for performance and reliability. The integration layer manages the integration with external systems, such as social media platforms and accounting software, ensuring seamless data flow and functionality expansion.
Dividing the system into modular components improves maintainability and flexibility. Clearly defined APIs enable independent development and version control mechanisms to manage different module versions. A modular logging system aids in easy debugging and troubleshooting of specific components.
System Components and Architecture
- Client Layer
A good solution in this scenario would be a mobile application built using React Native or Flutter( for cross-platform compatibility). It will serve as the primary interface for hot dog stand operators to manage sales, discounts, and inventory. This application must be lightweight, mobile-friendly, and capable of running smoothly on a smartphone or tablet.
We must ensure the app is accessible and conside color contrasts, button sizes, and voice-over compatibility for street transactions.
2. Application Layer
The system handles a wide variety of tasks: data processing, inventory, sales tracking, social media integration, and accounting exports. To manage incoming requests, we can create an API Gateway. This way, we will have a single entry point for all client requests, allowing request routing, composition, and protocol translation.
Further, in terms of scalability and flexibility, it would be a good direction to consider a microservices architecture for the backend. Each microservice will handle a specific domain so we can better manage the system as a whole.
In addition, we can also utilize AWS Lambda or Google Cloud Functions for lightweight, event-driven components, such as sending inventory alerts or processing discount calculations. Serverless architectures can dynamically scale to handle requests without provisioning servers, making them a cost-effective and efficient solution.
3. Data Layer
The Hot Diggety Dog POS system requires a database that can handle dynamic data such as sales, inventory, and user profiles. Considering this, we can consider MongoDB due to its flexibility in handling such data. The system can organize and retrieve data more efficiently by using collections to store relevant information. Scaling the system is also possible with MongoDB through horizontal expansion using sharding. This allows data to be distributed across multiple servers to maintain performance under increased load.
4. Integration Layer
When it comes to the integration layer, clearrely from the perspective of social media platforms as mentioned before we are going to integrate with their respective APIs for location-based promotions and updates.
For communication between our POS, inventory management component, and accounting component, a viable solution would be to use RESTful APIs or message queues. Asynchronous communication between these systems through APIs or message queues helps to improve inventory management and accounting processes.
5. Infrastructure Layer
We should consider deploying our POS system on a cloud platform like AWS, Google Cloud, or Azure. Doing so will allow us to use their global infrastructure, ensuring high availability and fault tolerance. Additionally, the system will automatically scale up or down based on real-time demand (e.g., lunch rushes or weekend events). This way, we can be confident that our business can handle critical sales periods.
Content Delivery Network (CDN): To reduce latency, it is recommended to use a Content Delivery Network (CDN), to serve static assets closer to users. Customers and operators can quickly access menus, promotional images, and app resources using a CDN, even during peak traffic.
Load Balancers: We can also consider to use load balancers to distribute traffic across servers or containers, enhancing the application’s responsiveness and availability. Load balancers distribute incoming traffic among multiple servers to prevent any single server from becoming overwhelmed during peak times.
6. Observability and Monitoring
Monitoring and logging systems are necessary because they help us ensure efficient operations and a seamless user experience for hot dog stand operators and customers. Additionally, it is essential to configure alerting mechanisms to respond to critical issues quickly.
Non-functional requirements
In the specific context of the Hot Dog Stand POS system, tailored non-functional requirements are paramount to its success in the dynamic street environment. Here are the most crucial ones and why they were chosen for our context and requirements:
1. Performance:
Fast and responsive performance is crucial for efficiently handling transactions, especially during high-traffic periods. Azure’s scalable infrastructure allows the POS system to scale resources dynamically based on demand. By utilizing Azure App Service and AKS, for example, resources can be automatically scaled to handle surges in traffic, ensuring optimal performance for operators and customers.
2. Reliability
Azure provides fault-tolerant services like Azure SQL Database and Cosmos DB, which are reliable for data storage and processing. These services’ automated monitoring and alerting features can detect and address issues proactively, ensuring that the POS system operates reliably in diverse conditions. Moreover, Azure’s SLA-backed service level agreements guarantee high uptime, ensuring consistent POS system performance.
3 . Availability
Since our application works in a dynamic environment, reliability is critical. To maintain accessibility and responsiveness at all times, we can ensure redundancy across multiple availability zones to prevent interruptions. Load balancers distribute incoming traffic to avoid server overload and continuous monitoring of system health helps detect and resolve issues swiftly. Auto-scaling dynamically adjusts resource allocation to accommodate fluctuations in demand.
4. Security
Ensuring security is crucial to safeguarding sensitive transaction data and customer information from unauthorized access or breaches and maintaining trust and compliance with regulations. Azure offers comprehensive security features, such as encryption, identity management, and threat detection, that protect the POS system against cyber threats. Azure Active Directory enables secure authentication, while Azure Security Center continuously monitors potential vulnerabilities and generates actionable insights to mitigate risks.
5. Scalability
Scalability is crucial for accommodating growth in transaction volume and user base. It ensures the POS system can smoothly scale up or down to meet increasing demand. With Azure’s cloud-native architecture and services like AKS and Cosmos DB, the POS system can handle spikes in transaction volume during busy periods without sacrificing performance or reliability.
6. Resilience
It is important to regularly backup data and have a disaster recovery plan in place. Additionally, consider monitoring system health and logging for quick troubleshooting.
Conclusion:
We must carefully consider functional and non-functional requirements to build a reliable, user-friendly, and comprehensive point-of-sale (POS) system. By utilizing modern technologies and following best practices in software development, we can create a POS system for Hot Diggety Dog that meets and exceeds the merchant’s expectations. This will ensure a scalable, secure, and efficient platform for years.
Previous articles on the subject
Mastering Modern Application Development: A Comprehensive Guide
