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Reactive Streams v1.0.1 Release Notes

Release Date: 2017-08-09 // over 6 years ago

  • Announcement:

    After more than two years since 1.0.0, we are proud to announce the immediate availability of Reactive Streams version 1.0.1.

    🚀 Since 1.0.0 was released Reactive Streams has managed to achieve most, if not all, it set out to achieve. There are now numerous implementations, and it is scheduled to be included in JDK9.

    🚀 Also, most importantly, there are no semantical incompatibilities included in this release.

    When JDK9 ships, Reactive Streams will publish a compatibility/conversion library to seamlessly convert between the java.util.concurrent.Flow and the org.reactivestreams namespaces.

    Highlights:

    • Specification
      • A new Glossary section
      • Description of the intent behind every single rule
      • No breaking semantical changes
      • Multiple rule clarifications
    • Interfaces
      • No changes
      • Improved JavaDoc
    • Technology Compatibility Kit (TCK)
      • Improved coverage
      • Improved JavaDoc
      • Multiple test alterations

    Specification clarifications 1.0.1

    Publisher Rule 1

    1.0.0: The total number of onNext signals sent by a Publisher to a Subscriber MUST be less than or equal to the total number of elements requested by that Subscriber´s Subscription at all times.

    1.0.1: The total number of onNext´s signalled by a Publisher to a Subscriber MUST be less than or equal to the total number of elements requested by that Subscriber´s Subscription at all times.

    ⚡️ Comment: Minor spelling update.

    Publisher Rule 2

    1.0.0: A Publisher MAY signal less onNext than requested and terminate the Subscription by calling onComplete or onError.

    1.0.1: A Publisher MAY signal fewer onNext than requested and terminate the Subscription by calling onComplete or onError.

    ⚡️ Comment: Minor spelling update.

    Publisher Rule 3

    1.0.0: onSubscribe, onNext, onError and onComplete signaled to a Subscriber MUST be signaled sequentially (no concurrent notifications).

    1.0.1: onSubscribe, onNext, onError and onComplete signaled to a Subscriber MUST be signaled in a thread-safe manner—and if performed by multiple threads—use external synchronization.

    🚦 Comment: Reworded the part about sequential signal and its implications, for clarity.

    Subscriber Rule 6

    1.0.0: A Subscriber MUST call Subscription.cancel() if it is no longer valid to the Publisher without the Publisher having signaled onError or onComplete.

    1.0.1: A Subscriber MUST call Subscription.cancel() if the Subscription is no longer needed.

    Comment: Rule could be reworded since it now has an intent section describing desired effect.

    Subscriber Rule 11

    1.0.0: A Subscriber MUST make sure that all calls on its onXXX methods happen-before [1] the processing of the respective signals. I.e. the Subscriber must take care of properly publishing the signal to its processing logic.

    1.0.1: A Subscriber MUST make sure that all calls on its signal methods happen-before the processing of the respective signals. I.e. the Subscriber must take care of properly publishing the signal to its processing logic.

    🚦 Comment: Rule slightly reworded to use the glossary for signal instead of the more ad-hoc name "onXXX methods". Footnote was reworked into the Intent-section of the rule.

    Subscription Rule 1

    1.0.0: Subscription.request and Subscription.cancel MUST only be called inside of its Subscriber context. A Subscription represents the unique relationship between a Subscriber and a Publisher [see 2.12].

    1.0.1: Subscription.request and Subscription.cancel MUST only be called inside of its Subscriber context.

    🚚 Comment: Second part of rule moved into the Intent-section of the rule.

    Subscription Rule 3

    1.0.0: Subscription.request MUST place an upper bound on possible synchronous recursion between Publisher and Subscriber[1].

    1.0.1: Subscription.request MUST place an upper bound on possible synchronous recursion between Publisher and Subscriber.

    Comment: Footnote reworked into the Intent-section of the rule.

    Subscription Rule 4

    1.0.0: Subscription.request SHOULD respect the responsivity of its caller by returning in a timely manner[2].

    1.0.1: Subscription.request SHOULD respect the responsivity of its caller by returning in a timely manner.

    Comment: Footnote reworked into the Intent-section of the rule.

    Subscription Rule 5

    1.0.0: Subscription.cancel MUST respect the responsivity of its caller by returning in a timely manner[2], MUST be idempotent and MUST be thread-safe.

    1.0.1: Subscription.cancel MUST respect the responsivity of its caller by returning in a timely manner, MUST be idempotent and MUST be thread-safe.

    Comment: Footnote reworked into the Intent-section of the rule.

    Subscription Rule 9

    1.0.0: While the Subscription is not cancelled, Subscription.request(long n) MUST signal onError with a java.lang.IllegalArgumentException if the argument is <= 0. The cause message MUST include a reference to this rule and/or quote the full rule.

    1.0.1: While the Subscription is not cancelled, Subscription.request(long n) MUST signal onError with a java.lang.IllegalArgumentException if the argument is <= 0. The cause message SHOULD explain that non-positive request signals are illegal.

    👻 Comment: The MUST requirement to include a reference to the rule in the exception message has been dropped, in favor of that the exception message SHOULD explain that non-positive requests are illegal.

    Subscription Rule 13

    1.0.0: While the Subscription is not cancelled, Subscription.cancel() MUST request the Publisher to eventually drop any references to the corresponding subscriber. Re-subscribing with the same Subscriber object is discouraged [see 2.12], but this specification does not mandate that it is disallowed since that would mean having to store previously cancelled subscriptions indefinitely.

    1.0.1: While the Subscription is not cancelled, Subscription.cancel() MUST request the Publisher to eventually drop any references to the corresponding subscriber.

    Comment: Second part of rule reworked into the Intent-section of the rule.

    Subscription Rule 15

    1.0.0: Calling Subscription.cancel MUST return normally. The only legal way to signal failure to a Subscriber is via the onError method.

    1.0.1: Calling Subscription.cancel MUST return normally.

    Comment: Replaced second part of rule with a definition for return normally in the glossary.

    Subscription Rule 16

    1.0.0: Calling Subscription.request MUST return normally. The only legal way to signal failure to a Subscriber is via the onError method.

    1.0.1: Calling Subscription.request MUST return normally.

    Comment: Replaced second part of rule with a definition for return normally in the glossary.

    Subscription Rule 17

    1.0.0: A Subscription MUST support an unbounded number of calls to request and MUST support a demand (sum requested - sum delivered) up to 263-1 (java.lang.Long.MAX_VALUE). A demand equal or greater than 263-1 (java.lang.Long.MAX_VALUE) MAY be considered by the Publisher as “effectively unbounded”[3].

    1.0.1: A Subscription MUST support an unbounded number of calls to request and MUST support a demand up to 263-1 (java.lang.Long.MAX_VALUE). A demand equal or greater than 263-1 (java.lang.Long.MAX_VALUE) MAY be considered by the Publisher as “effectively unbounded”.

    Comment: Rule simplified by defining demand in the glossary, and footnote was reworked into the Intent-section of the rule.

    TCK alterations 1.0.1

    • 🛠 Fixed potential resource leaks in partially consuming Publisher tests (#375)
    • 🛠 Fixed potential resource leaks in partially emitting Subscriber tests (#372, #373)
    • Renamed untested_spec305_cancelMustNotSynchronouslyPerformHeavyCompuatation to untested_spec305_cancelMustNotSynchronouslyPerformHeavyComputation (#306)
    • 👍 Allow configuring separate timeout for "no events during N time", allowing for more aggressive timeouts in the rest of the test suite if required (#314)
    • 🆕 New test verifying Rule 2.10, in which subscriber must be prepared to receive onError signal without having signaled request before (#374)

    - 🚦 The verification of Rule 3.9 has been split up into 2 different tests, one to verify that an IllegalArgumentException is sent, and the other an optional check to verify that the exception message informs that non-positive request signals are illegal.

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