统一架构 第4部分：服务

[中文适用范围]： IEC 62541-4:2025 定义了 OPC 统一架构（OPC UA）服务。所定义的服务是一组抽象的远程过程调用（RPC），由 OPC UA 服务器实现，并由 OPC UA 客户端调用。所有 OPC UA 客户端和服务器之间的交互均通过这些服务进行。所定义的服务被视作抽象，因为本文件未指定任何特定的 RPC 实现机制。IEC 62541-6 指定了一个或多个用于实现的具体映射。例如，IEC 62541-6 中的一个映射是 UA-TCP、UA-SC、UA-Binary。在该情况下，本文档中描述的服务将表现为 OPC UA 二进制编码的有效载荷，通过 OPC UA 安全会话进行安全保护，并通过 OPC UA TCP 进行传输。并非所有 OPC UA 服务器都实现了所有定义的服务。IEC 62541-7 定义了配置文件，这些配置文件规定了为了符合特定配置文件，必须实现哪些服务。附录 A 中描述了浏览路径名称的 BNF（Backus-Naur 形式）。第四版取消并替代了 2020 年发布的第三版。本版构成技术修订。与上一版相比，本版包括以下重大技术变更：a) 向方法调用服务中添加新定义，允许可选的方法参数；b) 添加对 SystemStatusChangeEventType 的引用，用于事件监控项错误场景；c) 对如何确定证书是否可信的通用描述进行了增强；d) 添加对 ECC 的支持；e) 向 AggregateFilterResult 结构添加修订后的 AggregateConfiguration；f) 向 BrowseDirection 枚举数据类型中添加 INVALID；g) 向 TimestampsToReturn 枚举数据类型中添加 INVALID；h) 添加定义，以确保如果重传队列是可选的，订阅功能仍能正常工作；i) 添加客户端检查，使其与服务器证书检查对称；j) 明确说明“本地”顶级域名不会由服务器添加到证书中，也不会在从 LDS-ME 返回时由客户端检查；k) 添加对已颁发身份令牌过期行为的定义；l) 向 ActivateSession 添加状态码 Good_PasswordChangeRequired；m) 将 AdditionalInfo 限制为调试模式下的服务器；n) 添加新状态码 Bad_ServerTooBusy；o) 添加定义，用于规定服务器证书必须包含在 GetEndpoints 响应中的情况。 [外文原描述]： IEC 62541-4:2025 defines the OPC Unified Architecture (OPC UA) Services. The Services defined are the collection of abstract Remote Procedure Calls (RPC) that are implemented by OPC UA Servers and called by OPC UA Clients. All interactions between OPC UA Clients and Servers occur via these Services. The defined Services are considered abstract because no particular RPC mechanism for implementation is defined in this document. IEC 62541‑6 specifies one or more concrete mappings supported for implementation. For example, one mapping in IEC 62541‑6 is to UA-TCP UA-SC UA-Binary. In that case the Services described in this document appear as OPC UA Binary encoded payload, secured with OPC UA Secure Conversation and transported via OPC UA TCP. Not all OPC UA Servers implement all of the defined Services. IEC 62541‑7 defines the Profiles that dictate which Services must be implemented in order to be compliant with a particular Profile. A BNF (Backus-Naur form) for browse path names is described in Annex A. This fourth edition cancels and replaces the third edition published in 2020. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) addition of new definitions to Method Call Service to allow optional Method arguments; b)addition of reference to SystemStatusChangeEventType for event monitored item error scenarios; c) enhancement of the general description of how determining if a Certificate is trusted; d) addition of support for ECC; e) addition of revisedAggregateConfiguration to AggregateFilterResult structure; f) addition of INVALID to the BrowseDirection enumeration data type; g) addition of INVALID to the TimestampsToReturn enumeration data type; h) addition of definitions that make sure the subscription functionality works if retransmission queues are optional; i) addition of client checks has been added to be symmetric to the Server Certificate check has been added; j) clarification that ‘local’ top level domain is not appended by server into certificate and not checked by client when returned from LDS-ME; k) addition of a definition for expiration behaviour of IssuedIdentityTokens; l) addition of status code Good_PasswordChangeRequired to ActivateSession; m) restriction of AdditionalInfo to servers in debug mode; n) addition of new status code Bad_ServerTooBusy; o) addition of definition for cases where server certificate must be contained in GetEndpoints response.