FINOS CALM and architecture as code

Architecture diagrams are useful for communication, but a diagram alone is difficult to validate, compare, or connect to delivery controls. The Common Architecture Language Model—CALM—from FINOS treats architecture as structured, version-controlled data that tooling can validate, render, and govern.

CALM is an open specification rather than a diagram format. Its official introduction describes a machine-readable language and toolchain for keeping design intent closer to implementation.

The core model

A CALM architecture describes several connected concepts:

• nodes represent systems, services, databases, networks, actors, or other architectural elements;
• interfaces describe interaction points exposed by nodes;
• relationships express interaction, connection, deployment, or composition;
• controls attach domain requirements and evidence to relevant elements;
• metadata and decorators add business, deployment, security, or organisational context;
• patterns provide reusable architectural structures and constraints.

The CALM core concepts define this vocabulary. Stable identifiers are important because relationships, controls, generated views, and external systems must refer to the same element over time.

From diagram to decision model

A visual line between an application and database may hide the protocol, identity, network boundary, data class, encryption requirement, and ownership. A structured relationship can make those properties explicit. CALM distinguishes interactions, technical connections, deployment, and composition, allowing tools to ask questions that a drawing cannot reliably answer.

For example, a platform can validate that a confidential-data flow uses an approved protocol, terminates at an approved interface, and has the required control configuration. The resulting diagram remains useful, but it becomes a view generated from governed architecture data rather than the only source.

Patterns and platform recommendations

CALM patterns can define required nodes and relationships without fixing every product choice. An enterprise platform can combine a pattern with a service catalogue:

1. capture workload requirements and constraints;
2. select a compatible architecture pattern;
3. match abstract pattern roles to approved enterprise services;
4. apply controls to nodes and relationships;
5. validate the completed architecture;
6. generate diagrams, documentation, and review evidence.

This model is directly relevant to an Architecture Solution Blueprint platform. CALM can provide a portable representation at the architecture boundary, while the platform supplies organisation-specific recommendations, ownership, certification logic, and workflow.

Controls need evidence

CALM controls distinguish a requirement from its configuration. A requirement might say that a connection must use an approved encrypted protocol; the configuration records how the architecture satisfies it. The controls documentation shows how schemas can define and validate this evidence.

Passing schema validation does not prove the deployed system is compliant. A mature implementation links control configuration to infrastructure policy, tests, runtime inventory, or other evidence and detects drift between declared and observed state.

Adoption sequence

Start with one recurring architecture pattern and a small vocabulary. Map existing platform services to node and interface definitions, encode a few high-value controls, validate in CI, and generate a view that teams already need. Avoid modelling the entire enterprise before proving that the representation improves a real decision.

Version schemas, patterns, and organisational extensions. Provide migration tooling when identifiers or constraints change. Treat exceptions as explicit, time-bound records rather than invalid models stored outside the system.

CALM is most valuable when architecture data participates in delivery: a pull request can validate a change, a platform can recommend compatible services, and governance can review evidence tied to the same model engineers use.