index.adoc

{smallrye-fault-tolerance} Documentation

{smallrye-fault-tolerance} {smallrye-fault-tolerance-version} is an implementation of Eclipse {microprofile-fault-tolerance} {microprofile-fault-tolerance-version} with additional features not defined by the specification.

It provides a declarative, annotation-based API for guarding method calls:

@ApplicationScoped
public class MyService {
    @Retry // (1)
    public String hello() {
        ...
    }
}

1. If hello() throws an exception, the invocation will be retried several times, until the method returns a value.

It also provides a programmatic API to build reusable guards:

public class MyService {
    private static final FaultTolerance<String> guard = FaultTolerance.<String>create()
        .withFallback().handler(() -> "fallback").done() // (1)
        .build();

    public String hello() throws Exception {
        return guard.call(() -> externalService.hello()); // (2)
    }
}

1. If the guarded call throws an exception, the fallback value will be returned instead.

2. The guarded call simply invokes some external service.

Caution

The fault tolerance strategies provided by {smallrye-fault-tolerance} are best suited for guarding network interactions. To handle ordinary exceptions, it is typically best to use the plain old try / catch / finally blocks. Using {smallrye-fault-tolerance} as a replacement of exception handling is often a bad idea.

Note	Some additional features may have experimental status, marked by the @Experimental annotation. The programmatic API to build reusable guards, as mentioned above, is one example, but there are more.

Runtimes

Runtimes that currently use {smallrye-fault-tolerance} include:

• Quarkus

• WildFly

Navigation

This documentation site has several sections, as you can see in the menu.

How-to Guides

How-tos are task-oriented guides that let you quickly start using some feature. They provide a short overview, but not many details.

Tip	If you’re just starting with {smallrye-fault-tolerance}, start with the how-tos.

References

References are detailed guides that let you understand some feature in depth. They also provide information about more advanced options or features.

Tip	If the how-to guide doesn’t answer a question you have, the reference guide should.

Integration

The articles here address concerns that runtimes integrating {smallrye-fault-tolerance} might have. Useful for people who maintain {smallrye-fault-tolerance} integration into some bigger framework or platform, but not required for application developers.

Internals

A few random articles that describe some parts of the {smallrye-fault-tolerance} code base. Useful for prospective contributors or generally curious users, but not required for application developers.