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ddd-ts-kit

ddd-ts-kit/aspects-outside-in

Architecture id: aspects/outside-in. Default severity: error in recommended, error in strict.

Applies to: every production file under the source root, except infrastructure/ of a context and the platform directory; domain/ and application/ are left to the layer rules.

Why

Section titled “Why”

Logging, metrics, retry, timeout, circuit breaking and caching are applied from outside the code they wrap: the policy of a whole application is read in one place, the composition root, and changes without touching a class. The decorator form is the exception, kept for an adapter whose policy is part of what the adapter is (a client of a provider that documents its own retry and timeout rules). On a route, in a module file, in a published language or in the shared kernel, a decorator hides a policy where nobody looks for one.

Reported

Section titled “Reported”
  • an import of @ddd-ts-kit/aspects/decorators in presentation/, in <context>.module.ts, in published-language/, in any other production file of a context outside infrastructure/, in the shared kernel, in main.ts and in any other source under the source root (apps/<context>/main.ts included)

Incorrect:

src/contexts/billing/presentation/http/issue-invoice.route.ts
import { Retry } from '@ddd-ts-kit/aspects/decorators';

Correct:

src/contexts/billing/billing.module.ts
import { retry, timeout } from '@ddd-ts-kit/aspects';


builder.bind(PaymentGateway).toClass(StripePaymentGateway, [PaymentSettings]).with(retry({ attempts: 3 }), timeout(2000));


// src/contexts/billing/infrastructure/external/stripe-payment.gateway.ts
import { Retry } from '@ddd-ts-kit/aspects/decorators';

Details

Section titled “Details”

Only the /decorators entry is judged: the wrappers of @ddd-ts-kit/aspects (retry, timeout, aspects, the bus middlewares) are what a module file and main.ts are expected to import. Static imports, type-only imports, export ... from, dynamic import() and require() are all read.

In domain/ and application/ every entry of @ddd-ts-kit/aspects is already refused by layer-domain-purity and layer-application-inward: this rule stays silent there, so that one import gives one report. Tests and files outside the source root (scripts, config files) are not judged.

Options

Section titled “Options”

None. platformDir and sourceRoot of ddd-ts-kit.config.json say where the platform and the sources are.

rules."aspects/outside-in" in ddd-ts-kit.config.json set to off silences the rule, and // ddd-ts-kit-disable-next-line aspects/outside-in -- <reason> silences one line, exactly as for ddd-ts-kit check.

Limits

Section titled “Limits”
  • A decorator re-exported by a file of infrastructure/ or of the platform and imported from there is not followed.
  • A home-made decorator built on weave or on an aspect of the root entry is not recognised.
  • With layer/domain-purity or layer/application-inward set to off, nothing reports the decorators in that layer.

With the CLI checker

Section titled “With the CLI checker”

ddd-ts-kit check reports the same id from the import specifiers it reads in the text of the files, with the same exemptions. This rule is the authority.