opcda-bridge

Reusable async Rust client for the opcda-bridge gateway's gRPC API. It provides typed capabilities, lazy paged browsing, progressive live search, persistent indexed search and index controls, list-servers, read, and write operations without bringing in the command-line client's presentation dependencies.

[dependencies]
opcda-bridge = "0.4"

This crate has its own independent release version. It does not need to match the client or gateway version; applications should select a compatible protocol and capability contract.

Use Client::gateway_info() to retrieve the gateway-wide protocol profile without an OPC DA server, or Client::compatibility() to evaluate the reusable library's profile. For older gateways, pass a server ProgID to Client::compatibility(Some("...")) so the library can infer the legacy capabilities contract. The result reports per-feature compatibility and whether the exact package pair is covered by boundary evidence; protocol overlap, not package-version equality, governs normal operation.

The library exposes typed capabilities, one-page browse sessions, explicit continuation and session close operations, progressive search events, and read/write methods. Browse pages are not automatically drained; callers that need bulk results must collect pages explicitly.

Client::read returns semantic values. For an OPC DA VT_BSTR, TagValue::value contains the exact BSTR contents without added or removed quote characters.

use opcda_bridge::{
    BrowsePageRequest, Client, SearchIndexRequest, SearchMatchMode, SearchRequest,
};

# async fn example() -> opcda_bridge::Result<()> {
let mut client = Client::connect("localhost:7600").await?;
let root = client.browse("Kepware.KepServerEX.V5", 200).await?;

if let Some(token) = root.next_page_token.clone() {
    let request = BrowsePageRequest::next(
        "Kepware.KepServerEX.V5",
        root.session_id.clone(),
        None,
        token,
        200,
    );
    let _next_page = client.browse_page(request).await?;
}

let mut search = client
    .search_stream(SearchRequest::new(
        "Kepware.KepServerEX.V5",
        "Device1",
        SearchMatchMode::Contains,
    ))
    .await?;
while let Some(event) = search.message().await? {
    println!("{event:?}");
}

let status = client.search_index_status("Kepware.KepServerEX.V5").await?;
if status.configured {
    let indexed = client
        .search_index(SearchIndexRequest::new(
            "Kepware.KepServerEX.V5",
            "Device1 PV",
            SearchMatchMode::Contains,
        ))
        .await?;
    for found in indexed.matches {
        println!("{}: {}", found.display_name, found.item_id);
    }
}
client.close_browse_session(root.session_id).await?;
# Ok(())
# }

Indexed search never falls back to live namespace traversal. Each response includes the index readiness state and has_more; returned ItemIDs preserve the server's exact identity and do not contain browse-session node keys. Use refresh_search_index and control_search_index for explicit refresh, pause, resume, and cancel operations.

See the crate documentation for method signatures and the repository README for gateway setup and protocol details.

opcda-bridge 0.4.5

opcda-bridge