Struct PvaClient

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pub struct PvaClient { /* private fields */ }

Expand description

High-level PVAccess client.

Provides pvget, pvput, pvmonitor, and pvinfo methods that hide the underlying protocol handshake.

let client = PvaClient::builder().build();
let val = client.pvget("MY:PV").await?;

Implementations§

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impl PvaClient

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pub fn builder() -> PvaClientBuilder

Create a builder for configuring a PvaClient.

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pub async fn pvget(&self, pv_name: &str) -> Result<PvGetResult, PvGetError>

Fetch the current value of a PV.

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pub async fn pvget_fields( &self, pv_name: &str, fields: &[&str], ) -> Result<PvGetResult, PvGetError>

Fetch a PV with field filtering (equivalent to pvget -r "field(value,alarm)").

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pub async fn pvput( &self, pv_name: &str, value: impl Into<Value>, ) -> Result<(), PvGetError>

Write a value to a PV.

Accepts anything convertible to serde_json::Value:

client.pvput("MY:PV", 42.0).await?;
client.pvput("MY:PV", "hello").await?;
client.pvput("MY:PV", serde_json::json!({"value": 1.5})).await?;

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pub async fn pvput_fields( &self, pv_name: &str, value: impl Into<Value>, fields: &[&str], ) -> Result<(), PvGetError>

Write to a PV with explicit field selection (dotted paths).

fields is forwarded as the PUT pvRequest. An empty slice is treated as “all fields” (server returns full descriptor on INIT).

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pub async fn open_put_channel( &self, pv_name: &str, ) -> Result<PvaChannel, PvGetError>

Open a persistent channel for high-rate PUT streaming.

Resolves the PV, establishes a channel, and completes the PUT INIT handshake. The returned PvaChannel is ready for immediate put calls.

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pub async fn open_put_channel_fields( &self, pv_name: &str, fields: &[&str], ) -> Result<PvaChannel, PvGetError>

Open a persistent PUT channel with explicit field selection.

An empty fields slice requests all fields from the server.

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pub async fn pvmonitor<F>( &self, pv_name: &str, callback: F, ) -> Result<(), PvGetError>
where F: FnMut(&DecodedValue) -> ControlFlow<()>,

Subscribe to a PV and receive live updates via a callback.

The callback returns ControlFlow::Continue to keep listening or ControlFlow::Break to stop the subscription.

use std::ops::ControlFlow;

client.pvmonitor("MY:PV", |value| {
    println!("{value:?}");
    ControlFlow::Continue(())
}).await?;

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pub async fn pvmonitor_fields<F>( &self, pv_name: &str, fields: &[&str], callback: F, ) -> Result<(), PvGetError>
where F: FnMut(&DecodedValue) -> ControlFlow<()>,

Subscribe to a PV with explicit field selection (dotted paths).

fields is the MONITOR pvRequest. Each entry may be a top-level field ("value") or a dotted nested path ("alarm.severity"). An empty slice requests all fields.

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pub async fn pvmonitor_with_options<F>( &self, pv_name: &str, fields: &[&str], options: MonitorOptions, callback: F, ) -> Result<(), PvGetError>
where F: FnMut(&DecodedValue) -> ControlFlow<()>,

Subscribe to a PV with explicit field selection and monitor options.

See MonitorOptions — in particular, set pipeline to request PVAccess monitor pipelining (flow-controlled delivery with client ACKs). When pipelining is disabled this behaves identically to pvmonitor_fields.

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