clojure-protobuf provides a Clojure interface to Google's protocol buffers. Protocol buffers can be used to communicate with other languages over the network, and they are WAY faster to serialize and deserialize than standard Clojure objects.

Getting started

Add the dependency to your project.clj

Assuming you have the following in resources/proto/person.proto:

message Person {
  required int32  id    = 1;
  required string name  = 2;
  optional string email = 3;
  repeated string likes = 4;
}

Compile the proto using the protobuf compiler and include the resulting .java code in your project

protoc --java_out=./ -proto_dir=resources/proto person.proto

Now you can use the protocol buffer in Clojure:

(use 'flatland.protobuf.core)
(import Example$Person)

(def Person (protodef Example$Person))

(def p (protobuf Person :id 4 :name "Bob" :email "bob@example.com"))
=> {:id 4, :name "Bob", :email "bob@example.com"}

(assoc p :name "Bill"))
=> {:id 4, :name "Bill", :email "bob@example.com"}

(assoc p :likes ["climbing" "running" "jumping"])
=> {:id 4, name "Bob", :email "bob@example.com", :likes ["climbing" "running" "jumping"]}

(def b (protobuf-dump p))
=> #<byte[] [B@7cbe41ec>

(protobuf-load Person b)
=> {:id 4, :name "Bob", :email "bob@example.com"}

A protocol buffer map is immutable just like other clojure objects. It is similar to a struct-map, except you cannot insert fields that aren't specified in the .proto file.