Luigi De Masi created CAMEL-24871:
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Summary: Add Jev-backed semantic predicates for the Choice EIP
Key: CAMEL-24871
URL: https://issues.apache.org/jira/browse/CAMEL-24871
Project: Camel
Issue Type: New Feature
Components: camel-ai, eip
Reporter: Luigi De Masi
h2. Motivation
Support semantic conditions in Camel's Choice EIP using Jev, TypeSafe AI's
decision model. A route author should be able to express a condition such as
"Does this message request a refund?" and use the result in
{{choice().when().otherwise()}} with an explicit probability threshold.
Jev's Noul primitive evaluates a yes/no proposition against supplied text or
structured state and returns a probability between 0 and 1. It does not return
a separate confidence field. This maps naturally to a Camel predicate once the
route author defines the threshold and how to handle uncertainty.
h2. Proposed behavior
Provide reusable Jev evaluation and predicate support, with the public DSL and
module placement to be agreed during design. The integration should allow route
authors to:
* Select the message body or explicitly chosen exchange data as the state, and
configure the question and optional yes/no criteria.
* Configure the model, credentials, request timeout, and probability threshold;
allow pinning a model version.
* Retain the probability on the exchange so the route can distinguish a
positive match, a negative result, and an uncertain result while preserving the
original message body.
* Evaluate multiple independent questions in one request when they share the
same state, then reuse their results in successive predicates.
* Route timeouts, API errors, and invalid or missing results through Camel's
error handling. These failures must not silently become a false predicate or
ordinary business fallback.
h2. Example routing behavior
For a refund-request question, an illustrative policy is:
* {{p >= 0.9}}: route to the refund-request handler.
* {{p <= 0.1}}: route to the normal handler.
* Otherwise: route to review or another configured fallback.
These thresholds are examples to validate against the application's data, not
universal defaults. The predicate classifies intent; downstream code remains
responsible for deciding and authorizing any business action.
h2. Design considerations
{{Predicate.matches(Exchange)}} is synchronous. Making an HTTP call directly
from each predicate would block the evaluating thread and could introduce
successive remote calls when several {{when}} branches are checked. A preferred
starting point is a Jev evaluation step before the choice, followed by
predicates reading exchange-scoped results. Any direct predicate facade should
document its blocking behavior and avoid implying automatic batching of
independent predicate invocations.
Preserve the Choice EIP's existing first-match behavior: when several
independent predicates match, branch order determines which handler runs.
Asking one Jev Choice question for the best category is a different operation
and should not silently replace that behavior. No change to Camel's core
Predicate contract is proposed.
Typed responses do not guarantee correct classifications. Document uncertainty
handling and the model's limitations, including sensitivity to irrelevant or
adversarial message content. Keep the submitted state explicit rather than
forwarding the entire exchange by default.
h2. Acceptance criteria
* A documented example routes messages through {{choice/when/otherwise}} using
Jev results, including an uncertainty branch.
* Automated tests with a stubbed HTTP service cover threshold boundaries,
uncertain results, overlapping matches and first-match priority, body
preservation, and timeout/error/invalid-response handling.
* Multiple questions can share one evaluation request and their results can be
reused without a remote call per branch.
* Documentation describes synchronous predicate constraints, model selection,
credentials, timeouts, and error handling. Tests do not require live
credentials.
h2. References
* [Jev introduction|https://docs.typesafe.ai/introduction]
* [Noul primitive and probability
semantics|https://docs.typesafe.ai/primitives/noul]
* [HTTP API|https://docs.typesafe.ai/api]
* [Model limitations|https://docs.typesafe.ai/model-jaggedness/jev-1.13]
* Camel {{core/camel-api/src/main/java/org/apache/camel/Predicate.java}}
* Camel
{{core/camel-core-processor/src/main/java/org/apache/camel/processor/ChoiceProcessor.java}}
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