Annotations in Providence

The explicit use of annotations is one of the big differences between Apache Thrift and Providence, and is used for a fair bit of type modifications.


Annotations are specified by adding a set of key-value pairs inside parentheses after a type or field is defined, where the key is a qualified identifier, and the value is a quoted string literal. Note that the annotations apply to whatever was defined before itself. E.g.:

struct MyStruct {
    1: string field (annotation.on.field = "value")
    2: i32    other (annotation.on.other = "value")
} (annotation.on.struct = "value")

Or in IDL syntax:

ANNOTATIONS          ::= '(' ANNOTATION [ [',' ';'] ANNOTATION ]* ')'



Annotation Specifications

A number of annotations that modify different subsystems are:

Container Type

The set and map container types uses by default an ImmutableSet or the ImmutableMap guava classes respectively, which uses a simple hash storage. Two other variants exists, which is controlled by the container annotations.

  • container = "SORTED": On fields with set or map type only, will replace the default hash-based container with a sorted container. In java that is the ImmutableSortedMap or similar.
  • container = "ORDERED": On fields with set or map type only, will replace the default hash-based container with an order-preserving container. In java that is the LinkedHashMap or similar.

Java Specific Annotations

  • java.implements Each java message (union, struct, exception) can implement additional interfaces specified by this annotation. Full package and class name. Note that the message is still a full implementation, so the interface methods need to be implemented (declared) by the generated code, or have default implementations.
  • java.exception.class Which exception class to inherit from. This must be the full class path of an exception. Note that whether it is an exception is not checked in the generator, it is plainly trusted as the exception class. The exception must have a constructor with a single string argument which sets the exception message.
  • java.service.methods.throws Which replaces the declared exceptions with the given exception class on the service interface only. Also note that:
    • The property is not inherited, and only applies to the methods declared on the service with the annotation.
    • All the declared exceptions must extend the given exception.
    • The exception class must be available at compile time, and have a constructor that takes the message string only.
    • Any exception that not declared, including those that extend the base exception class will be handled as an application level failure, throwing PApplicationException.
    • The client will still only throw the declared exceptions (and IOException).
  • java.public.constructor will create a public constructor with all fields as params. Note that this used to be default on, but is now default off and triggered with this annotation.


  • message.field: Which field should be used for exception messages. This will default to "message", and will fail silently using the default exception message based on toString() if the field is not found.
  • deprecated = "<message>": Will mark the associated methods, service or class as being deprecated (should not be used). Since the syntax for deprecating a class is different for each language, it is handled in annotation, and should e.g. generate @Deprecated annotations in java.
  • json.compact = "": Enables the use of the compact syntax in the json serializer.
  • ref.enum = "program.EnumName": If successfully referencing an enum will add setter for the enum in the builder and a refFieldName() getter that returns the enum name if set AND valid.