然而，中介程序模型提供一个所有消息的服务数据对象(Service Data Object, SDO)接口，以及访问这些不同种类消息属性和元数据的通用API。

However, the mediation programming model provides a Service data Object (SDO) interface to all messages and a common API for accessing properties and metadata.

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HTTP API 可以检索、创建和更新资产内容，但是不能操作资产的已扩展数据和系统元数据。

The HTTP API can retrieve, create, and update the content of the asset, but cannot manipulate the extended metadata of the asset and the system metadata.

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Bean验证规范通过元数据请求API暴露一些约束的基本元数据信息。

The Bean Validation specification exposes some of the constraints' basic metadata information through a metadata request API.

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