In other words C# and those new languages won't be able to serialize the
descriptor?

On 9 October 2015 at 19:44, 'Feng Xiao' via Protocol Buffers <
protobuf@googlegroups.com> wrote:

> The decision is not to support proto2 in C# (and probably also for all
> other languages that are new in v3.0.0+).
>
> On Fri, Oct 9, 2015 at 10:42 AM, Teddy Zhang <lostind...@gmail.com> wrote:
>
>> Will the C# implementation support proto2 message as well?
>> What is the compatibility story between proto2 and proto 3? I assume the
>> wire format is compatible as long as no proto 3 exclusive features are used.
>>
>>
>> On Tuesday, August 4, 2015 at 5:43:36 AM UTC-7, Jon Skeet wrote:
>>
>>> That looks like you're expecting a protobuf.net-style approach - to
>>> which the answer is "no" and will continue to be "no".
>>>
>>> The C# support will continue to be based on generated code, but there's
>>> a new code generator and runtime now in the master branch. The main changes
>>> from the previous code are:
>>>
>>> - proto3-only support (no proto2 at all)
>>> - mutable generated types rather than the Java-style builders and
>>> immutable messages
>>>
>>> Jon
>>>
>>> On Monday, 3 August 2015 22:50:06 UTC+1, The Nguyen Xuan wrote:
>>>>
>>>> Does this version support object type in C# ?
>>>>
>>>> ex:
>>>>
>>>> [ProtoMember(1)]
>>>> public object A {get;set;}
>>>>
>>>> thank.
>>>>
>>>> Vào 11:51:01 UTC+7 Thứ Năm, ngày 11 tháng 12 năm 2014, Feng Xiao đã
>>>> viết:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I just published protobuf v3.0.0-alpha-1 on our github site:
>>>>> https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-1
>>>>>
>>>>> This is the first alpha release of protobuf v3.0.0. In protobuf
>>>>> v3.0.0, we will add a new protobuf language version (aka proto3) and
>>>>> support a wider range of programming languages (to name a few: ruby, php,
>>>>> node.js, objective-c). This alpha version contains C++ and Java
>>>>> implementation with partial proto3 support (see below for details). In
>>>>> future releases we will add support for more programming languages and
>>>>> implement the full proto3 feature set. Besides proto3, this alpha version
>>>>> also includes two other new features: map fields and arena allocation. 
>>>>> They
>>>>> are implemented for both proto3 and the old protobuf language version (aka
>>>>> proto2).
>>>>>
>>>>> We are currently working on the documentation of these new features
>>>>> and when it's ready it will be updated to our protobuf developer guide
>>>>> <https://developers.google.com/protocol-buffers/docs/overview>. For
>>>>> the time being if you have any questions regarding proto3 or other new
>>>>> features, please post your question in the discussion group.
>>>>>
>>>>> CHANGS
>>>>> =======
>>>>> Version 3.0.0-alpha-1 (C++/Java):
>>>>>
>>>>>   General
>>>>>   * Introduced Protocol Buffers language version 3 (aka proto3).
>>>>>
>>>>>     When protobuf was initially opensourced it implemented Protocol
>>>>> Buffers
>>>>>     language version 2 (aka proto2), which is why the version number
>>>>>     started from v2.0.0. From v3.0.0, a new language version (proto3)
>>>>> is
>>>>>     introduced while the old version (proto2) will continue to be
>>>>> supported.
>>>>>
>>>>>     The main intent of introducing proto3 is to clean up protobuf
>>>>> before
>>>>>     pushing the language as the foundation of Google's new API
>>>>> platform.
>>>>>     In proto3, the language is simplified, both for ease of use and  to
>>>>>     make it available in a wider range of programming languages. At the
>>>>>     same time a few features are added to better support common idioms
>>>>>     found in APIs.
>>>>>
>>>>>     The following are the main new features in language version 3:
>>>>>
>>>>>       1. Removal of field presence logic for primitive value fields,
>>>>> removal
>>>>>          of required fields, and removal of default values. This makes
>>>>> proto3
>>>>>          significantly easier to implement with open struct
>>>>> representations,
>>>>>          as in languages like Android Java, Objective C, or Go.
>>>>>       2. Removal of unknown fields.
>>>>>       3. Removal of extensions, which are instead replaced by a new
>>>>> standard
>>>>>          type called Any.
>>>>>       4. Fix semantics for unknown enum values.
>>>>>       5. Addition of maps.
>>>>>       6. Addition of a small set of standard types for representation
>>>>> of time,
>>>>>          dynamic data, etc.
>>>>>       7. A well-defined encoding in JSON as an alternative to binary
>>>>> proto
>>>>>          encoding.
>>>>>
>>>>>     This release (v3.0.0-alpha-1) includes partial proto3 support for
>>>>> C++ and
>>>>>     Java. Items 6 (well-known types) and 7 (JSON format) in the above
>>>>> feature
>>>>>     list are not implemented.
>>>>>
>>>>>     A new notion "syntax" is introduced to specify whether a .proto
>>>>> file
>>>>>     uses proto2 or proto3:
>>>>>
>>>>>       // foo.proto
>>>>>       syntax = "proto3";
>>>>>       message Bar {...}
>>>>>
>>>>>     If omitted, the protocol compiler will generate a warning and
>>>>> "proto2" will
>>>>>     be used as the default. This warning will be turned into an error
>>>>> in a
>>>>>     future release.
>>>>>
>>>>>     We recommend that new Protocol Buffers users use proto3. However,
>>>>> we do not
>>>>>     generally recommend that existing users migrate from proto2 from
>>>>> proto3 due
>>>>>     to API incompatibility, and we will continue to support proto2 for
>>>>> a long
>>>>>     time.
>>>>>
>>>>>   * Added support for map fields (implemented in C++/Java for both
>>>>> proto2 and
>>>>>     proto3).
>>>>>
>>>>>     Map fields can be declared using the following syntax:
>>>>>
>>>>>       message Foo {
>>>>>         map<string, string> values = 1;
>>>>>       }
>>>>>
>>>>>     Data of a map field will be stored in memory as an unordered map
>>>>> and it
>>>>>     can be accessed through generated accessors.
>>>>>
>>>>>   C++
>>>>>   * Added arena allocation support (for both proto2 and proto3).
>>>>>
>>>>>     Profiling shows memory allocation and deallocation constitutes a
>>>>> significant
>>>>>     fraction of CPU-time spent in protobuf code and arena allocation
>>>>> is a
>>>>>     technique introduced to reduce this cost. With arena allocation,
>>>>> new
>>>>>     objects will be allocated from a large piece of preallocated
>>>>> memory and
>>>>>     deallocation of these objects is almost free. Early adoption shows
>>>>> 20% to
>>>>>     50% improvement in some Google binaries.
>>>>>
>>>>>     To enable arena support, add the following option to your .proto
>>>>> file:
>>>>>
>>>>>       option cc_enable_arenas = true;
>>>>>
>>>>>     Protocol compiler will generate additional code to make the
>>>>> generated
>>>>>     message classes work with arenas. This does not change the
>>>>> existing API
>>>>>     of protobuf messages and does not affect wire format. Your
>>>>> existing code
>>>>>     should continue to work after adding this option. In the future we
>>>>> will
>>>>>     make this option enabled by default.
>>>>>
>>>>>     To actually take advantage of arena allocation, you need to use
>>>>> the arena
>>>>>     APIs when creating messages. A quick example of using the arena
>>>>> API:
>>>>>
>>>>>       {
>>>>>         google::protobuf::Arena arena;
>>>>>         // Allocate a protobuf message in the arena.
>>>>>         MyMessage* message = Arena::CreateMessage<MyMessage>(&arena);
>>>>>         // All submessages will be allocated in the same arena.
>>>>>         if (!message->ParseFromString(data)) {
>>>>>           // Deal with malformed input data.
>>>>>         }
>>>>>         // Must not delete the message here. It will be deleted
>>>>> automatically
>>>>>         // when the arena is destroyed.
>>>>>       }
>>>>>
>>>>>     Currently arena does not work with map fields. Enabling arena in a
>>>>> .proto
>>>>>     file containing map fields will result in compile errors in the
>>>>> generated
>>>>>     code. This will be addressed in a future release.
>>>>> =======
>>>>>
>>>>> Thanks,
>>>>> Feng
>>>>>
>>>>
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