Software Architecture Themes and Questions

2023-10-05

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A software architect works with a development team to define how features shall be realized. The selected approach should support corporate governance and legal constraints.

A new digital product must fulfill a set of technical aspects to be usable. Technical constraints are the non-functional requirements of the product ^[1].

Some of these technical requirements are encountered again and again when developing digital products.

Any software product must provide solutions to standard problems.

Typical aspects are user interface, persistence, configuration and compatibility issues.

Experienced software designers often have a list of questions any software architecture should answer.

Below the questions I answered every time when implementing a new application.

User Experience

How should the users interact with the product? How can the application streamline customer activities and diminish user mistakes?

Usability: The navigability of the visual components shall follow standards ^[2].
Internationalization and localization: The application shall be usable in various countries through i18n and l16n.
Corporate identity: The user interface shall follow corporate identity such as color palette, logo, and navigation.
Translation: All human-readable texts shall be translated in the supported languages.
Accessibility: The solution shall be accessible to various groups of users. Accessibility laws exist in most of the countries.
User manual: A user manual shall be provided to the users.

Hire a professional interface and usability expert. Trained collaborators are key to designing world-class user interfaces.

Configuration

How should the product be configured during production and at customer site?

Deployment configuration: Defines how the application is deployed on the target system.
Parametrization: Parametrizes the application to a specific country and customer.
Configuration persistence: The configuration of the application through the producing company and the user shall be persisted.
Configuration migration: Existing configurations need to be migrated to new versions of the solutions.

XML is an obsolete technology. Do not use it in new projects. Consider JSON or TOML.

Avoid storing configuration parameters into a relational database.

Data Management

How are data persisted in the application? Which information should be persisted is a requirement. The manner to persist data is a design decision.

Persistence: How does the application persist data?
Archiving: How is older information archived?
Data migration: How is persisted data migrated when a new application version is deployed?
Backwards compatibility: Sometimes the application shall handle older persisted information or configuration without explicit migration. The same constraints can often be requested when communicating with external systems.

Data is often the most valuable asset of an organization.

Organizations often store information over decades. This data must be accessible in the future.

Internal Communication

How do the application components communicate inside the software?

Task communication, synchronization and parallelization: How do threads communicate inside the system? How do components communicate inside the software?
Interprocess communication: How does the application communicate with external systems?
Transaction handling: How are transactions handled to provide atomic changes of a set of related data? Scalability: How to scale the system when more requests must be processed?
Response times: How do we guaranty soft and hard response deadlines?
Availability: How do we ensure that the application is available when needed?

Internal communication shall always use asynchronous communication implemented through the actor model. It provides scalability, availability, and response time. Transaction handling is provided through eventual consistency and storno approach.

By all means avoid the global lock approach which probably will kill your application in the long term.

Errors

How are runtime faults and errors handled in the product?

Interface data validation: Input information shall always be validated to avoid data corruption.
Plausibility checks: Which information is plausible? Which data values hint to an error or corruption? Plausibility checks are also applicable for internal data.
Error and exception handling: How do we detect errors? How do we propagate them through the system and outside? How do we recover from an error? How do we log any error for further offsite analysis?

Error handling is a crosscutting concept in the application. Try using the same approach through the whole system to diminish semantic complexity.

Integration

How can you integrate the product into a landscape?

Deployment: How should the solution be deployed in a landscape? Is incremental update requested? How do we update the configuration of a subset of the landscape in a consistent way?
Authentication: How do we authenticate the users of the application?
Authorization: How do we limit access to specific functionality or data to selected users?
External interfaces: How do we document and validate interfaces to external applications?
Batch processing: Should we process batches of requests?
Business rules: How can our application be integrated in the processes of the organizational landscape?

Modular monolith approach is currently the most cost-effective approach to structure a software application. Communication between bounded domains is primary asynchronous and message based.

Use standards for authentication and authorization to minimize security risks.

Monitoring

How could the organization infer that happened during the product use in the field? What are the operational processes?

Logging: How should you trace interesting activities? Log all exceptions, errors, all data received or sent to another system as a minimum.
Monitoring and data collection for offsite analysis: How should you monitor activities of interest in the system?
Auditing: Legal and governance relevant activities should be audited. Audit logs should often be human-readable due to legal considerations.
Reporting: How can a user create reports?
Disaster recovery: How should our system recover after a catastrophic crash with data or configuration loss?

Monitoring is essential in a successful product. Do not skip it.

The solution should support automatic offsite processing to extract relevant scenarios from huge data sets.

Development Practices

How should the development team work to produce the right product with the right quality?

Coding guidelines: How should you write source code? The selected guidelines shall be automatically enforced with tools. Use available guidelines for your technology stack to increase quality.
Design patterns: How can you design and implement recurring functionalities found in most systems? Use well-documented design patterns and code idioms.
Functional requirement verification: How can you ensure all functional requirements are implemented? Consider automatic acceptance testing.
Non-functional requirements verification: How can ensure all non-functional requirements are correctly implemented? Consider using fitness functions.
Code legibility: How to encourage your developers to write legible and maintainable source code?

The standard digital development approach is agile.

Use the current version of your technology stack. Laggards are losers in the technology field.

Legal Aspects

Which legal restrictions apply to the product ^[3]?

Industry norms: Which standards should you fulfill to avoid being sued?
Data confidentiality: Which confidentiality regulations should you implement to avoid being sued?
Accessibility laws: Which user interface functions should you provide to avoid being sued?

Lessons Learnt

Each architect has preferred solutions for these themes. You can freely select your approach as long as the non-functional requirements are fulfilled.

Beware that the capabilities of your development team will influence which answers should be selected. Avoid solutions overwhelming your developers.

Consider choosing well-known approaches to reduce training and coaching effort.

Invest effort to create an evolvable architecture. The chosen architecture shall adapt to encompass newly discovered requirements.

1. The ISO standard 25010, 25012, 25040 and 25059 is a family of software and data quality standards. They are an example of non-functional requirement nomenclature.

2. Major platforms such as macOS or Android have extensive visual and usability guidelines.

3. Senior designers should be aware of legal and copyright aspects for digital products.