Breaking changes (Feb 2020)

Prior to February 2020, all API client libraries targeted GAX (Google.Api.Gax and related packages) version 2.x. As part of supporting Grpc.Core 2.x and the IAsyncEnumerable<T> interface that's compatible with C# 8, a new major version of GAX was released, with the first beta in February 2020. This contains breaking changes, and we've taken advantage of the opportunity this provides to make some separate breaking changes in code generation at the same time.

This document provides a guide to these breaking changes, most of which apply to most or all API libraries. Any breaking changes which only affect a single API library are documented in the corresponding version history instead.

Platform support

GAX v3 supports .NET Standard 2.0 and .NET 4.6.1 (and higher versions of each). (For reference, GAX v2 supported .NET Standard 1.3 or 1.5 depending on the exact package, and .NET 4.5.)

This means that if you want to use the API libraries targeting GAX v3, you need to be using .NET Core 2.0 or .NET 4.6.1, or a higher version of either of these.

Client creation

Creating a client with the default endpoint, credentials, settings etc is still supported via the static Create and CreateAsync methods on the client class. If you need any customization, please use the corresponding client builder class. For example:

// Synchronous creation with defaults
var client1 = SpeechClient.Create();

// Asynchronous creation with defaults
var client2 = await SpeechClient.CreateAsync();

// Customized synchronous creation
var client3 = new SpeechClientBuilder
   UserAgent = "custom-user-agent"


The previous GAX ServiceEndpoint class has been removed. Endpoints are now specified as strings. For example:

// Customized synchronous creation
var client3 = new SpeechClientBuilder
    Endpoint = ""

Retry settings

RetrySettings and BackoffSettings types

The GAX v2 RetrySettings class contained two BackoffSettings members, one for timeouts and one for backoff between attempts. A separate CallTiming class contained the expiration and the retry settings.

In GAX v3, RetrySettings is only about backoff, and contains the multiplier, filter etc directly. This is based on the retry specification from gRPC. The expiration is directly specified in CallSettings.

Generated methods in API libraries

Previous versions exposed properties and methods for retry settings of grouped operations, e.g. IdempotentRetryFilter, GetDefaultRetryBackoff() and GetDefaultTimeoutBackoff(). These are not generated by the new generator, and there is no equivalent. Instead, use the settings applicable to individual RPCs.

Resource names

Multi-pattern resources

When a resource name is represented by multiple patterns, the previous generator created multiple resource name types and a "one-of" type to represent "one of those resource names". For example, in the Logging.V2 API, we had a LogNameOneof class which would be a LogName, OrganizationLogName, FolderLogName, or BillingLogName.

The new generator generates a single LogName resource that can handle each of the patterns, with a static factory method for each one:

  • FromProjectLog
  • FromOrganizationLog
  • FromFolderLog
  • FromBillingAccountLog

Multi-resource methods

Some RPCs accept multiple resource names. This is typically the case when specifying the parent of a resource name which itself has multiple patterns. Again, this was previously represented using a "one-of" type, but the new generator creates an overload for each resource type, as well as one accepting a string.

Common resource names

In order to work with multiple APIs simply, some common resource names are in GAX. These are:

  • ProjectName
  • LocationName
  • OrganizationName
  • FolderName
  • BillingAccountName

All of these are in the Google.Api.Gax.ResourceNames namespace.

Some API libraries previously used some of these resource name patterns - particularly LocationName - but had their own types. For example, the Logging API library used to include its own OrganizationName, BillingName, ProjectName and FolderName types, all within Google.Cloud.Logging.V2. These were maintained across minor releases for backward compatibility, but have been removed in the new major version.

Code broken by this change will normally just need to import the Google.Api.Gax.ResourceNames namespace.