Request and response
APIs where the caller needs an answer, a decision or a consistent read within a bounded time.
Integration / Services
Integration & APIs
API, event-driven and enterprise integration architecture designed for clear ownership, evolution, security and operability.
Integration shapes the enterprise
Integration is architecture, not plumbing.
Poor integration creates coupling, duplicated logic, hidden dependencies and fragile change. Good integration establishes ownership, contracts and failure behaviour at every boundary.
The integration estate
Boundaries decided deliberately.
Every interface is a commitment. Where it sits, who owns it and how it fails determines how easily the estate can change.
Choose the interaction deliberately
The mechanism should follow the semantics.
Each pattern fits different timing, consistency and failure requirements. Using one for everything is how estates become fragile.
Events
Notification of something that has happened, where consumers decide what to do about it.
Messaging and commands
Directed work with explicit delivery expectations, where the sender needs the work performed.
Batch and files
High-volume, periodic exchange where timing and atomicity requirements suit it better than a live interface.
Workflow and orchestration
Long-running, multi-step processes with compensation, visibility and human steps where they belong.
Replication and synchronisation
Deliberate copying of data where read patterns or availability justify it, with ownership made explicit.
API and event decisions
What has to be decided before interfaces proliferate.
| Theme | The decision | What it costs to leave it implicit |
|---|---|---|
| Contracts | What each interface guarantees, in terms consumers can rely on. | Every consumer is coupled to behaviour nobody has documented. |
| Versioning | How interfaces change while consumers migrate independently. | Deployments that must be coordinated across teams indefinitely. |
| Discovery | How the estate is found and understood by the teams that join it. | Duplicate capabilities built because nobody knew one existed. |
| Error semantics | What failures mean, what is retryable and what the caller should do. | Retry storms and silent data loss across interface boundaries. |
| Ownership | Who is accountable for each interface and its consumers. | Interfaces nobody can change and nobody will retire. |
Contracts and ownership are cheapest to establish at the first consumer, and most expensive to retrofit at the hundredth.
Operate the integration estate
Integration has to be run, not only built.
Availability of the estate depends on how interfaces behave when their counterparts do not.
- 01
Dependency health
Visibility of which interfaces are degraded and what that means for the business journeys above them.
Standing visibility
- 02
Correlation
Traceability across asynchronous boundaries where a single business action spans several systems.
End-to-end tracing
- 03
Failure handling
Dead-letter handling, quarantine and replay procedures that are exercised rather than assumed.
Recovery procedures
- 04
Version support
A defined period of support for each interface version and a credible retirement process.
Lifecycle policy
- 05
Consumer impact
Change assessed against the consumers it affects, including the ones nobody has spoken to.
Change assessment
Modernise without a big-bang rewrite
Establish seams, then move consumers.
Legacy interfaces can be encapsulated before they are replaced.
We create contracts around existing behaviour, migrate consumers incrementally and retire point-to-point integrations only once evidence shows they are unused. The estate changes while continuing to operate.
- Encapsulate first
- Migrate incrementally
- Prove then retire
- Keep it operating
Engagement enquiries
Discuss the integration estate.
Describe the systems that must work together, the change that is difficult today and who owns each boundary. That is usually enough to identify the architectural problem.
Useful links
No middleware product is recommended before the interfaces and their ownership are understood.