How do their APIs compare?

These two projects are fundamentally different kinds of software, so their "APIs" aren't really comparable in the same sense — let me break down what each actually is.

jodaorg/joda-time: a language library API

Joda-Time exposes a Java class library API — no network/HTTP surface at all. Its API is a set of interfaces and immutable value classes meant to be used in-process:

• Core interfaces define contracts for reading date/time data without mutation:
  • ReadableInstant — an instant on the millisecond timeline, meant to be used as a parameter type when a method only needs to read a moment in time [src/main/java/org/joda/time/ReadableInstant.java:L17-L36]
  • ReadableDateTime — an instant queryable via calendar fields (year, month, etc.) [src/main/java/org/joda/time/ReadableDateTime.java:L20-L32]
  • ReadablePartial — a "local" time that only supports a subset of fields (e.g., just month/day, no zone) and is Comparable by field order [src/main/java/org/joda/time/ReadablePartial.java:L18-L36]
• Concrete immutable/thread-safe classes implement these: Interval (a span between two instants) [src/main/java/org/joda/time/Interval.java:L27-L49], Years and Weeks (type-safe single-field periods with plus(), minus(), multipliedBy(), dividedBy()) [src/main/java/org/joda/time/Years.java:L23-L39, src/main/java/org/joda/time/Weeks.java:L23-L39], and DateTimeComparator for comparing dates from various input types (String, Calendar, Date, Long, or ReadableInstant) [src/main/java/org/joda/time/DateTimeComparator.java:L23-L45].
• Utility base classes like AbstractPeriod provide shared implementation (getValues(), get(DurationFieldType)) that concrete period types build on [src/main/java/org/joda/time/base/AbstractPeriod.java:L92-L118].

There's no request/response, auth, or transport concern here — the "API" is purely method signatures and type contracts for date/time arithmetic.

yunaiv/yudao-cloud: distributed HTTP/RPC service APIs

Yudao-cloud is a microservices platform, so its APIs are Spring-based HTTP/RPC contracts between services, with heavy use of DTOs, validation annotations, and OpenAPI (Schema) documentation:

• PermissionCommonApi defines cross-service RPC-style endpoints (GET .../has-any-permissions, .../has-any-roles, .../get-dept-data-permission) using @RequestParam and CommonResult<T> wrapper responses [yudao-framework/yudao-common/.../PermissionCommonApi.java:L16-L42].
• ApiErrorLogCommonApi exposes a POST .../create endpoint validated with @Valid @RequestBody, plus an @Async convenience wrapper (createApiErrorLogAsync) that fires the call without blocking on the result [yudao-framework/yudao-common/.../ApiErrorLogCommonApi.java:L17-L34].
• Request/response payloads are explicit DTO classes with per-field validation and Swagger/OpenAPI @Schema metadata, e.g. OperateLogCreateReqDTO (required user ID, type, action, request URL/IP/UA with @NotNull/@NotEmpty) [yudao-framework/yudao-common/.../OperateLogCreateReqDTO.java:L11-L48] and OAuth2AccessTokenCheckRespDTO (userId, userType, scopes, tenantId, expiry) [yudao-framework/yudao-common/.../OAuth2AccessTokenCheckRespDTO.java:L13-L33].

Key contrasts