NBJSONRPC005: Do not store service rentals in fields or properties

Property	Value
ID	NBJSONRPC005
Category	Usage
Default severity	Warning

Rentals obtained from ServiceBrokerClient.GetProxyAsync should be used and disposed of within the acquiring asynchronous method. Storing a rental in a field or property extends its lifetime beyond that scope and interferes with timely cache invalidation and service replacement. This rule also diagnoses storing an existing local rental or storing a rental through a conversion to object.

Avoid storing the rental:

this.rental = await client.GetProxyAsync(BrokeredServiceExamples.Greeter, cancellationToken: cancellationToken);

Instead, keep it local:

using ServiceBrokerClient client = new(broker);
using ServiceBrokerClient.Rental<IGreeter> rental = await client.GetProxyAsync(Greeter, cancellationToken: cancellationToken);
IGreeter greeter = rental.Proxy ?? throw new InvalidOperationException("The greeting service is unavailable.");
return await greeter.GreetAsync("Ada", cancellationToken);

For longer-lived service ownership, acquire the proxy directly from IServiceBroker and follow NBJSONRPC004. No automatic code fix is offered because moving a rental changes its lifetime and may require redesigning its owner. Suppress this diagnostic only when deliberately retaining a rental, and ensure it is disposed. This rule is the Nerdbank.JsonRpc counterpart of ServiceHub's ISB002.