SmallRye Fault Tolerance Documentation

SmallRye Fault Tolerance 6.2.2 is an implementation of Eclipse MicroProfile Fault Tolerance 4.0.2 with additional features not defined by the specification.

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

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)

    public String hello() throws Exception {
        return -> 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.
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.
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 that currently use SmallRye Fault Tolerance include:


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.

If you’re just starting with SmallRye Fault Tolerance, start with the how-tos.


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

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


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.


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.