Any contains an arbitrary serialized protocol buffer message along with a URL that describes the type of the serialized message.

Protobuf library provides support to pack/unpack Any values in the form of utility functions or additional generated methods of the Any type.

Example 1: Pack and unpack a message in C++.

 Foo foo = ...;
 Any any;
 any.PackFrom(foo);
 ...
 if (any.UnpackTo(&foo)) {
   ...
 }

Example 2: Pack and unpack a message in Java.

 Foo foo = ...;
 Any any = Any.pack(foo);
 ...
 if (any.is(Foo.class)) {
   foo = any.unpack(Foo.class);
 }

Example 3: Pack and unpack a message in Python.

 foo = Foo(...)
 any = Any()
 any.Pack(foo)
 ...
 if any.Is(Foo.DESCRIPTOR):
   any.Unpack(foo)
   ...

Example 4: Pack and unpack a message in Go

  foo := &pb.Foo{...}
  any, err := anypb.New(foo)
  if err != nil {
    ...
  }
  ...
  foo := &pb.Foo{}
  if err := any.UnmarshalTo(foo); err != nil {
    ...
  }

The pack methods provided by protobuf library will by default use 'type.googleapis.com/full.type.name' as the type URL and the unpack methods only use the fully qualified type name after the last '/' in the type URL, for example "foo.bar.com/x/y.z" will yield type name "y.z".

JSON

The JSON representation of an Any value uses the regular representation of the deserialized, embedded message, with an additional field @type which contains the type URL. Example:

 package google.profile;
 message Person {
   string first_name = 1;
   string last_name = 2;
 }

 {
   "@type": "type.googleapis.com/google.profile.Person",
   "firstName": <string>,
   "lastName": <string>
 }

If the embedded message type is well-known and has a custom JSON representation, that representation will be embedded adding a field value which holds the custom JSON in addition to the @type field. Example (for message google.protobuf.Duration):

 {
   "@type": "type.googleapis.com/google.protobuf.Duration",
   "value": "1.212s"
 }