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Why Dependencies Are the Hardest Part of Documenting Large Architectures

19 Jun 2025 5 min read
Why Dependencies Are the Hardest Part of Documenting Large Architectures

You know your system is complex. You've got dozens of services, APIs talking to APIs, data flowing through pipelines you haven't touched in months.

But ask a simple question — "What happens if we change this?" — and suddenly nobody's sure.

That's the dependency problem. And it's why documenting large architectures is so hard.

Dependencies are invisible until something breaks

In a small system, you can hold the whole thing in your head. You know that Service A calls Service B, which writes to Database C. Simple.

But systems grow. Teams split. New integrations get added "temporarily" and never removed. Before long, the architecture becomes a web of connections that exist only in scattered knowledge — a bit in someone's head, a bit in an old wiki page, a bit in code comments nobody reads.

The result? Dependencies stay invisible. They're not documented anywhere that matters. And you only discover them when something breaks.

  • A "minor" database change cascades into three downstream failures
  • An API deprecation affects services nobody knew were using it
  • A team renames a queue and breaks a workflow in another department

Every senior engineer has stories like this. The common thread is always the same: nobody knew what was connected to what.

What teams actually need

To document large architectures effectively, teams need visibility into:

  • Upstream dependencies — What does this component rely on?
  • Downstream dependencies — What relies on this component?
  • Integration touchpoints — How do systems connect at the boundaries?
  • Impact analysis — If I change X, what else is affected?

Without this, architecture documentation becomes a collection of isolated diagrams — pretty pictures that don't answer the questions that matter.

Implicit vs explicit dependencies

Implicit dependencies Explicit dependency graphs
Knowledge lives in people's heads Relationships captured in a model
Discovered during incidents Visible before changes happen
Partial, fragmented documentation Complete picture of connections
"Ask Dave, he knows" Self-service exploration
Manual impact analysis Automated dependency tracing
Implicit vs explicit dependencies comparison
Visual comparison showing how implicit dependencies remain hidden and fragmented, while explicit dependency graphs make all connections visible and queryable.

Most organizations operate on implicit dependencies. It works — until it doesn't. Until Dave goes on vacation. Until the incident happens at 2am and nobody remembers which systems depend on the one that's down.

Explicit dependency graphs flip this. Instead of discovering connections reactively, you can explore them proactively. You can ask "what depends on this?" and get an answer without scheduling a meeting.

Model-backed dependency visualization

The key insight is that dependencies need to live in your architecture model, not just your diagrams.

Model as single source of truth generating multiple views
A central architecture model serves as the single source of truth, generating multiple consistent views on demand.

When dependencies are part of the model, you can generate views dynamically. Filter by domain, system, or tag. Zoom in on what matters. Trace paths through the architecture without manually drawing every possible view.

Example of a system-wide dependency graph
A dependency graph centered on Dynamics 365 FO, revealing its connections to Magento eCommerce, Visma, and Reflex WMS.

Here's an example focused on Dynamics 365 FO. The graph reveals how this system connects to Magento eCommerce, Visma Account Receivable, and Reflex WMS. You can immediately see the integration touchpoints and trace what would be affected by a change — without digging through documentation or asking around.

Example of filter options in dependency graph
Filter controls allow you to narrow the dependency graph by domain, system, or tags to focus on relevant connections.

Filtering lets you cut through the noise. Large architectures can have hundreds of components. Being able to narrow down to just what you need — a specific domain, a particular integration pattern, a set of tags — makes the difference between a useful tool and an overwhelming wall of boxes.

Making dependencies explicit in Revision

Revision's dependency graphs are built directly from your architecture model. Every relationship you capture is queryable. Every component knows what it connects to.

This means your documentation stays consistent. Update a relationship in one place, and every view that includes it reflects the change. No more outdated diagrams showing connections that no longer exist.

For teams doing serious application integration management, this changes how you work. You can map integration touchpoints clearly, avoid duplicate solutions, and share a living view of how systems connect — not a snapshot that was accurate six months ago.

The bigger your architecture gets, the more critical this becomes. Dependencies are the hardest part of documentation. Making them explicit is how you turn architecture from scattered knowledge into something your whole team can use.

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