MEP 18 -- Support Milvus 2.0 C++ SDK

Current state: Accepted

ISSUE: https://github.com/milvus-io/milvus/issues/7713

PRs:

Keywords: C++ SDK

Released: with Milvus 2.1

Authors:

Summary

Deliver C++ SDK toolkit with full functionality for Milvus 2.0. Provide both static lib and dynamic lib for users.

Motivation

We've seen many users demands for C++ SDK, it is probably the most useful SDK which could be used in distributed systems.

Public Interfaces

Client interfaces declaration:

class MilvusClient {
 public:
    static std::shared_ptr<MilvusClient>
    Create();

    virtual Status
    Connect(const ConnectParam& connect_param) = 0;

    virtual Status
    Disconnect() = 0;

    virtual Status
    CreateCollection(const CollectionSchema& schema) = 0;

    virtual Status
    HasCollection(const std::string& collection_name, bool& has) = 0;

    virtual Status
    DropCollection(const std::string& collection_name) = 0;

    virtual Status
    LoadCollection(const std::string& collection_name, const TimeoutSetting* timeout) = 0;

    virtual Status
    ReleaseCollection(const std::string& collection_name) = 0;

    virtual Status
    DescribeCollection(const std::string& collection_name, CollectionDesc& collection_desc) = 0;

    virtual Status
    GetCollectionStatistics(const std::string& collection_name, bool do_flush, CollectionStat& collection_stat) = 0;

    virtual Status
    ShowCollections(const std::vector<std::string>& collection_names, CollectionsInfo& collection_desc) = 0;
};

Design Details

TODO lists

API Design → Reference Java 1.1 SDK, Pymilvus SDK
Initial version of the code, finish all the frameworks, including how the sdk communicate with milvus cluster, how we do unit test.
Finish DDL, DML , Control API implementation
Unit Test
Usage examples
API Document
CI Test

ORM

To be decided

C++ versions to support

Support C++ version above C++11. The Reason is:

Wider user range, as may organizations and devices support C++11.
Easy to maintain as it will get a large group of developer support.

OS platform to support

For the supported platform, need to be tested with mainstream distributions(e.g. Ubuntu 18.04+, CentOS 7+) using google tests.

Milvus cpp SDK 1.1 using cmake, and only build a shared library as output. In this new SDK for milvus 2, the user can choose which version to be built by setting cmake options. Quality gates such as clang-format, clang-tidy, cpplint are needed.

Code Style

A basic rule of C++ code style:

Namespace should use lower_case
Class should use CamelCase
Class member should use lower_case_ (with a underscore append)
Enum member should use UPPER_CASE
Function should use CamelCase, and the private member Function use camelBack

For more details, follow the Google C++ Style Guide.

Test Plan

Unit test
1. C++ SDK will implement a mock milvus for basic testing, need to be tested with mainstream distributions(e.g. Ubuntu 18.04+, CentOS 7+)
2. Start a standalone milvus complicated test.
CI test
1. Do we need to setup basic CI test for further improvement?
Examples
1. finish all the examples in user guide and make sure it works like https://milvus.io/docs/v2.0.0/example_code.md

References