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Modify (C)

前置阅读

DarraUa_Subscription_Modify​

修改订阅的发布参数 (ModifySubscription 服务):

DARRA_OPCUA_API DarraUa_Status DARRA_OPCUA_CALL DarraUa_Subscription_Modify(
    DarraUa_SubscriptionHandle h,
    double                     new_publishing_interval_ms,
    uint32_t                   new_lifetime_count,
    uint32_t                   new_max_keep_alive_count,
    uint32_t                   new_max_notifications_per_publish,
    uint8_t                    new_priority,
    /* out */ double*          revised_publishing_interval_ms,
    /* out */ uint32_t*        revised_lifetime_count,
    /* out */ uint32_t*        revised_max_keep_alive_count);

revised_* 是服务端实际生效值 (服务端可能 revise 调整). 任意 out 指针可为 NULL 表示忽略.

double   rev_pub  = 0.0;
uint32_t rev_life = 0;
uint32_t rev_ka   = 0;

DarraUa_Subscription_Modify(
    sub,
    /*new_publish*/ 1000.0,
    /*new_lifetime*/ 600,
    /*new_max_ka*/ 30,
    /*new_max_notif*/ 0,
    /*new_priority*/ 0,
    &rev_pub, &rev_life, &rev_ka);

printf("Revised publishing = %.1f ms, lifetime = %u, max_ka = %u\n",
       rev_pub, rev_life, rev_ka);

DarraUa_Subscription_ModifyMonitoredItems​

批量修改 MI 采样参数 (ModifyMonitoredItems 服务):

typedef struct {
    uint32_t mi_handle;
    double   sampling_interval_ms;     /* -1 = 跟订阅 */
    uint32_t queue_size;               /* >= 1 */
    int32_t  discard_oldest;           /* 1 = 丢最旧, 0 = 丢最新 */
} DarraUa_MonitoredItemModifyRequest;

DARRA_OPCUA_API DarraUa_Status DARRA_OPCUA_CALL DarraUa_Subscription_ModifyMonitoredItems(
    DarraUa_SubscriptionHandle                 h,
    const DarraUa_MonitoredItemModifyRequest*  requests,
    uint32_t                                   count,
    DarraUa_Status*                            out_results,
    double*                                    out_revised_sampling_intervals,
    uint32_t*                                  out_revised_queue_sizes);

out_* 数组均由调用方按 count 分配, 任一可为 NULL 表示忽略.

DarraUa_MonitoredItemModifyRequest reqs[3] = {
    { mis[0], 50.0, 10, 1 },
    { mis[1], 50.0, 10, 1 },
    { mis[2], 50.0, 10, 1 },
};
DarraUa_Status results[3] = { 0 };
double rev_sample[3] = { 0 };
uint32_t rev_queue[3] = { 0 };

DarraUa_Subscription_ModifyMonitoredItems(sub, reqs, 3,
    results, rev_sample, rev_queue);

for (int i = 0; i < 3; ++i) {
    printf("mi=%u status=%s revised_sample=%.1f revised_queue=%u\n",
           reqs[i].mi_handle, DarraUa_StatusName(results[i]),
           rev_sample[i], rev_queue[i]);
}

QueueSize 与 DiscardOldest​

服务端为每个 MI 维护一个先进先出队列. 当客户端 Publish 来不及取时, 队列满了:

  • discard_oldest = 1 (默认) → 丢最旧, 保留最新
  • discard_oldest = 0 → 丢最新, 保留最旧

queue_size = 1 (默认) 只保留最新值, 适合"实时显示"; queue_size = N (N > 1) 适合"采样不能漏"的高频数据.

何时用 Modify 而不是删除重建​

场景推荐
改 publishingInterval / lifetime / sampling_Modify / _ModifyMonitoredItems (省 RPC, 不丢通知)
完全更换 NodeId / Attribute删 + 重建 (Modify 不能换 NodeId)
临时停一个 MISetMonitoringMode (Disabled), 比删除轻量

下一步​