The Analog Dependency Atlas: Hand‑Sketching System Boundaries Before You Add One More Microservice

You don’t need another microservice.

At least, not until you actually understand the system you already have.

Teams often reach for a new service as the default answer to scaling, performance, or organizational friction. But when your ecosystem is already a tangle of APIs, queues, gateways, and third‑party SaaS, adding “just one more” can quietly increase fragility instead of resilience.

This is where the Analog Dependency Atlas comes in: the deliberate practice of hand‑sketching your ecosystem and its boundaries before you introduce anything new.

Pen and paper might sound primitive in a world of auto‑generated service maps, but they’re exactly what you need to reveal the dependencies that tools miss, assumptions hide, and incidents later expose.

Why Start Analog in a Digital World?

Dependency graphs, observability platforms, and architecture dashboards are valuable—but they’re not neutral. They show what they’re instrumented to show. They reflect:

• The events that get logged
• The metrics that get collected
• The integrations you remembered to configure

They rarely reflect the whole system you actually run.

Hand‑sketched mapping works differently:

• It forces you to think, not just observe.
• It surfaces implicit knowledge living in people’s heads.
• It reveals gaps in your understanding as missing boxes and unlabeled arrows.

The result is not a beautiful diagram. The result is a conversation—a shared, system‑level understanding that becomes your first defense against accidental complexity.

Step 1: Inventory the Whole Ecosystem (Not Just the “Services”)

Before you can map dependencies, you need to know what actually exists. That means going beyond microservices and capturing the full environment.

Create a complete inventory of:

• Applications
  Web apps, mobile apps, internal tools, admin consoles, cron jobs.

• Microservices & APIs
  Public services, internal services, edge services, legacy endpoints.

• Data Stores
  Databases (SQL/NoSQL), data warehouses, caches, message queues, object storage.

• Compute Substrates
  Servers, VMs, containers, Kubernetes clusters, serverless functions.

• Middleware & Integration Layers
  Message brokers, ESBs, ETL tooling, workflow engines.

• Network & API Edges
  API gateways, load balancers, reverse proxies, service meshes.

• Identity & Access
  SSO providers, IAM systems, secrets managers.

• Third‑Party SaaS & External Services
  Payment processors, email/SMS providers, analytics, logging, feature flags.

This list should feel too long. That’s the point.

Without this inventory, any dependency map is at best a partial truth and at worst dangerously misleading. When incidents occur or changes go wrong, the root cause is often an “invisible” component: a queue nobody knew existed, an old gateway route still in use, a third‑party that became critical over time.

Step 2: Hunt for the Hidden Infrastructure

The most dangerous components in your system are often the ones nobody talks about:

• Middleware that silently transforms or enriches messages
• API gateways that apply authentication, throttling, and routing rules
• Legacy proxies kept for “backward compatibility”
• Shared databases accessed by multiple services

These components carry non‑obvious dependencies:

• A gateway timeout can look like “service X is failing” when the real constraint is at the edge.
• A shared database schema change can break multiple services you didn’t know depended on it.
• A middleware rule can enforce behavior you assume lives in the microservice code.

Pay special attention to these hidden layers when sketching. For each, ask:

• Who depends on this?
• Who owns it (if anyone)?
• What happens if it fails or changes?

Often, the answer to “who owns this?” is silence or finger pointing. That silence is a signal: you have a systemic risk, not just a tech debt item.

Step 3: Hand‑Sketch Before You Diagram

Now, actually draw.

Resist the temptation to open your favorite diagramming tool. Start with paper, sticky notes, or a whiteboard. The goal is discovery, not documentation.

How to Sketch Your Analog Dependency Atlas

1. Draw boxes for everything from your inventory
   Each box is a component: a service, a database, a gateway, a queue, a SaaS tool.

2. Connect them with arrows for real dependencies

   • “Service A calls Service B over HTTP”
   • “Service C writes to Database D”
   • “Web app uses Identity Provider E for login”

3. Label the arrows with protocols and semantics

   • REST / JSON, gRPC, Kafka, S3, Webhooks, etc.
   • Synchronous vs asynchronous
   • Critical path vs best‑effort

4. Highlight external boundaries
   Draw a thick line around your organization. Everything outside is an external dependency with its own reliability, SLAs, and change patterns.

5. Mark unknowns explicitly
   Use question marks where you’re not sure what talks to what, or how. Those unknowns are now tasks, not mysteries.

By the time you’re done, the page will look messy. That’s good. Complexity that was previously implicit is now visible.

Only after this messy analog stage should you consider formalizing a subset of the diagram in a digital tool.

Step 4: Define Ownership and Boundaries for Every Service

A microservice without clear ownership is just a distributed liability.

To get real value from a microservice architecture, you must answer for every component:

• Who owns this service?
  A team name, not a person. Ownership means responsibility for uptime, change, and evolution.

• What is its bounded context?
  What domain concepts does it own? What does it not own?

• What is the contract?
  APIs, SLAs, data models it exposes—and what is guaranteed not to change without coordination.

Compare this with many monolithic systems:

• Everyone can change everything in the codebase.
• Responsibility for failures is diffuse: “the app is down.”
• Coupling is hidden in shared libraries, global state, and big relational schemas.

Monoliths often suffer from ambiguous accountability. Microservices were supposed to fix this, but they only do if you enforce:

• One clearly named team per service or group of services.
• One clear system boundary per service.
• One clear contract that others rely on.

On your analog map, annotate each box with an owner. Anywhere you can’t write a team name, you’ve found:

• A boundary that’s not truly owned
• A platform surface that behaves like shared monolith infrastructure
• A risk hotspot where changes will be slow, political, or brittle

Microservices vs Monoliths: Ownership and Dependency Clarity

In a monolith:

• Dependencies are often code‑level: function calls, shared modules, shared tables.
• They’re hard to see without deep domain and code knowledge.
• Ownership is “the whole team owns the app,” which sounds good but often means “nobody owns anything specifically.”

In a microservice ecosystem done right:

• Dependencies are service‑level and contract‑driven: APIs, events, and schemas.
• They’re visible on a map and (ideally) in tooling.
• Ownership is per service, enabling clearer accountability and faster iteration.

But if you simply carve a monolith into smaller deployable units without explicit boundaries and ownership, you get:

• All the coupling of the monolith
• All the operational overhead of microservices
• None of the clarity about who is responsible for what

Your analog atlas helps you ask the key question:

Are we decomposing by domain and responsibility, or just by directory structure and tech stack?

Step 5: Think Like a Systems Architect, Not a Service Author

Microservices are local solutions. Incidents and reliability problems are global phenomena.

Borrowing from complex systems and optimization, you want a system‑level perspective:

• Identify critical paths: Which chains of services and components must work for a core user journey (e.g., “place order”) to succeed?
• Spot tight couplings: Where does a change in one component force changes in many others?
• Understand feedback loops: Retries, backoffs, circuit breakers, and autoscaling policies can create emergent behaviors like cascading failures.
• Evaluate trade‑offs: A new microservice might improve one team’s velocity while increasing cross‑team coordination cost and systemic risk.

When you’re looking at the entire analog map, ask:

• If this service slows down, what backs up behind it?
• If that SaaS provider goes down, what user journeys are broken?
• Where do we have single points of failure dressed up as “shared platforms”?

Only with this system‑level understanding can you honestly decide whether adding a new microservice is:

• A genuine boundary clarification, or
• Just more surface area for failure and coordination.

When (and Whether) to Add That Next Microservice

Once your Analog Dependency Atlas is in front of you, use it as a decision tool. Before you add one more microservice, validate:

1. Is there a clear new boundary?
   Does the proposed service encapsulate a cohesive domain or capability, or is it just carving code along technical lines?

2. Is there a clear owner?
   Is there a team eager and accountable to own it long‑term?

3. Does it reduce or increase systemic coupling?
   Do you retire old dependencies, or just add new ones on top?

4. Can you express its contract cleanly on the map?
   If the API or event model is hand‑wavy, the service boundary probably is too.

If you can’t answer these confidently, the most resilient move might be to improve what you have instead of multiplying services.

Conclusion: Draw First, Deploy Later

Modern systems fail not because we lack tools, but because we lack shared understanding.

An Analog Dependency Atlas—your hand‑sketched, brutally honest view of everything your system depends on—forces that understanding into the open:

• You inventory all components, not just the glamorous microservices.
• You expose hidden infrastructure and third‑party risks.
• You clarify ownership and boundaries so every box on the page has a responsible team.
• You think at the system level, weighing trade‑offs across the entire ecosystem.

Before you add the next microservice, pick up a pen. Draw the system you actually have. Only then decide if a new box—and all the arrows that come with it—is truly the best next move.