interface PooledConnection {
    client: any;
    session: any;
    inUse: boolean;
    key: string;
}
export declare class OpcUaConnectionPool {
    private static instance;
    private pools;
    private constructor();
    static getInstance(): OpcUaConnectionPool;
    getConnection(credentials: any): Promise<PooledConnection>;
    releaseConnection(connection: PooledConnection): void;
    private createKey;
    private createConnection;
    shutdown(): Promise<void>;
}
export {};