com.netflix.hystrix

Interface HystrixObservable<R>

Type Parameters:

R -

All Superinterfaces:

HystrixInvokable<R>

All Known Implementing Classes:

HystrixCollapser, HystrixCommand, HystrixObservableCollapser, HystrixObservableCommand

public interface HystrixObservable<R>
extends HystrixInvokable<R>

Common interface for executables that implement the Observable methods HystrixObservable.observe() and HystrixObservable.toObservable() so client code can treat them the same and combine in typed collections if desired.

Method Summary

Methods

Modifier and Type	Method and Description
rx.Observable<R>	observe() Used for asynchronous execution of command with a callback by subscribing to the Observable.
rx.Observable<R>	toObservable() Used for asynchronous execution of command with a callback by subscribing to the Observable.

Method Detail

observe

rx.Observable<R> observe()

Used for asynchronous execution of command with a callback by subscribing to the Observable.

This eagerly starts execution of the command the same as HystrixCommand.queue() and HystrixCommand.execute().

A lazy Observable can be obtained from HystrixObservable.toObservable().

Callback Scheduling

• When using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD this defaults to using Schedulers.computation() for callbacks.
• When using HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE this defaults to using Schedulers.immediate() for callbacks.

See https://github.com/ReactiveX/RxJava/wiki for more information.

Returns:

Observable<R> that executes and calls back with the result of the command execution or a fallback if the command execution fails for any reason.

Throws:

HystrixRuntimeException - if a fallback does not exist

• via Observer#onError if a failure occurs
• or immediately if the command can not be queued (such as short-circuited, thread-pool/semaphore rejected)

HystrixBadRequestException - via Observer#onError if invalid arguments or state were used representing a user failure, not a system failure

java.lang.IllegalStateException - if invoked more than once

toObservable

rx.Observable<R> toObservable()

Used for asynchronous execution of command with a callback by subscribing to the Observable.

This lazily starts execution of the command only once the Observable is subscribed to.

An eager Observable can be obtained from HystrixObservable.observe()

Callback Scheduling

• When using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD this defaults to using Schedulers.computation() for callbacks.
• When using HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE this defaults to using Schedulers.immediate() for callbacks.

See https://github.com/ReactiveX/RxJava/wiki for more information.

Returns:

Observable<R> that executes and calls back with the result of the command execution or a fallback if the command execution fails for any reason.

Throws:

HystrixRuntimeException - if a fallback does not exist

• via Observer#onError if a failure occurs
• or immediately if the command can not be queued (such as short-circuited, thread-pool/semaphore rejected)

HystrixBadRequestException - via Observer#onError if invalid arguments or state were used representing a user failure, not a system failure

java.lang.IllegalStateException - if invoked more than once