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lib/ocaml/README.md

Thrift OCaml Software Library

License

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Library

The library abstract classes, exceptions, and general use functions are mostly jammed in Thrift.ml (an exception being TServer).

Generally, classes are used, however they are often put in their own module along with other relevant types and functions. The classes often called t, exceptions are called E.

Implementations live in their own files. There is TBinaryProtocol, TSocket, TThreadedServer, TSimpleServer, and TServerSocket.

A note on making the library: Running make should create native, debug code libraries, and a toplevel.

Struct format

Structs are turned into classes. The fields are all option types and are initially None. Write is a method, but reading is done by a separate function (since there is no such thing as a static class). The class type is t and is in a module with the name of the struct.

enum format

Enums are put in their own module along with functions to_i and of_i which convert the ocaml types into ints. For example:

enum Numberz { ONE = 1, TWO, THREE, FIVE = 5, SIX, EIGHT = 8 }

==>

module Numberz = struct type t = | ONE | TWO | THREE | FIVE | SIX | EIGHT

let of_i = ... let to_i = ... end

typedef format

Typedef turns into the type declaration: typedef i64 UserId

==>

type userid Int64.t

exception format

The same as structs except that the module also has an exception type E of t that is raised/caught.

For example, with an exception Xception, raise (Xception.E (new Xception.t)) and try ... with Xception.E e -> ...

list format

Lists are turned into OCaml native lists.

Map/Set formats

These are both turned into Hashtbl.t's. Set values are bool.

Services

The client is a class “client” parametrized on input and output protocols. The processor is a class parametrized on a handler. A handler is a class inheriting the iface abstract class. Unlike other implementations, client does not implement iface since iface functions must take option arguments so as to deal with the case where a client does not send all the arguments.