edutap.data_models

Shared contracts of the eduTAP packages: controlled vocabularies, the Kafka message contract, and settings building blocks whose field names are meant to be identical in every container.

Why this exists

Three duplicates, all of them found in the field.

Vocabularies in three diverging copies. PassLifecycleState existed with eight values in lmu_edutap_common and with six in both lmu_edutap_full_view and edutap.data_provider. WalletType existed in four spellings.

The message contract. Header block, key rule and dead letter envelope have to be identical in six packages. Six copies diverge, and the divergence is invisible until a consumer quietly stops recognising a message.

Settings that should mean the same thing everywhere. environment is the clearest case: the same field name in every container, populated per service by the Swarm compose file, and read by the error tracker and the trace exporter alike.

What belongs here

The runtime package is the odd one out and says so. It is behaviour rather than a contract in the way a vocabulary is, and it is here because the behaviour is what several services have to agree on: the commit order, the dead letter naming, what a stop signal does. It is written against protocols, so the Kafka driver is not a dependency of this package — build_consumer() and build_dead_letter_producer() stay in the service, with its settings class. See the design record of 2026-08-11.

The pass lifecycle is spelled on three axes. IssuanceState is what the issuer did or wants and exists with no exemplar at all; InstanceState is what one exemplar at the holder is doing; HolderState is the summary of the second and is derived, never set. PassLifecycleState conflated the first two and is superseded — it is still reachable under edutap.data_models.vocabulary and warns when used.

Error tracking and trace export live in edutap.observability_settings, not here. The options that decide what may leave a process were chosen against measurements and are worth nothing apart from the sentry_sdk.init() call that applies them.

What does not

Table definitions of individual packages. edutap.db_definitions collects those through entry points, and that collection is what makes one package answerable for one schema. Move them here and nobody owns a schema any more.

Anything LMU-specific. lmu_edutap_common stays what it is; the edutap.* packages must not depend on it.

Dependency direction

This package depends on nothing from the eduTAP estate — only on pydantic, pydantic-settings and structlog. Everything else may depend on it. A library that knows about services is not a library.

structlog is the third and had to be argued for: the runtime loop's log records are structured — topic, partition, offset, reason — and that structure is their entire value in operation. Every consumer already uses it.

Usage

from edutap.data_models import WalletType
from edutap.data_models.messaging import TOPIC_PASS_STATE, build_headers
from edutap.data_models.settings import KafkaSettings


class MySettings(KafkaSettings):
    model_config = {"env_prefix": "EDUTAP_MY_SERVICE_"}


settings = MySettings()                      # aborts without EDUTAP_MY_SERVICE_TOPIC_PREFIX
topic = settings.topic(TOPIC_PASS_STATE)     # edutap.production.pass.state

Reaching a broker that requires mTLS is the same three settings fields everywhere — ca_file, cert_file, key_file, plus password for an encrypted key — and one function that turns them into driver options:

from edutap.data_models.runtime import transport_options

AIOKafkaConsumer(topic, bootstrap_servers=..., **transport_options(settings))

It returns {} when nothing is configured, which is the development case against a broker without TLS. Configuring only some of the three raises instead of falling back: against an SSL-only broker a silent fallback does not produce an unencrypted connection, it produces one that fails during the handshake — and that error names the broker rather than the secret nobody mounted.

The context is built from the standard library, so the Kafka driver stays out of this package's dependencies.

Development

make venv
make lint
make test-local

tox runs the suite across every supported Python version.

Design records

The design is written down under docs/superpowers/specs/.