// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and

/*
Package pscompat contains clients for publishing and subscribing using the
Pub/Sub Lite service.

This package is designed to compatible with the Cloud Pub/Sub library:
https://pkg.go.dev/cloud.google.com/go/pubsub. If interfaces are defined by the
client application, PublisherClient and SubscriberClient can be used as
substitutions for pubsub.Topic.Publish() and pubsub.Subscription.Receive(),
respectively, from the pubsub package. See the following examples:
https://pkg.go.dev/cloud.google.com/go/pubsublite/pscompat#example-NewPublisherClient-Interface
and
https://pkg.go.dev/cloud.google.com/go/pubsublite/pscompat#example-NewSubscriberClient-Interface.

The Cloud Pub/Sub and Pub/Sub Lite services have some differences:
  - Pub/Sub Lite does not support NACK for messages. By default, this will
    terminate the SubscriberClient. A custom function can be provided for
    ReceiveSettings.NackHandler to handle NACKed messages.
  - Pub/Sub Lite has no concept of ACK deadlines. Subscribers must ACK or NACK
    every message received and can take as much time as they need to process the
    message.
  - Pub/Sub Lite PublisherClients and SubscriberClients can fail permanently
    when an unretryable error occurs.
  - Publishers and subscribers will be throttled if Pub/Sub Lite publish or
    subscribe throughput limits are exceeded. Thus publishing can be more
    sensitive to buffer overflow than Cloud Pub/Sub.
  - Pub/Sub Lite utilizes bidirectional gRPC streams extensively to maximize
    publish and subscribe throughput.

More information about Pub/Sub Lite is available at
https://cloud.google.com/pubsub/lite.

Information about choosing between Cloud Pub/Sub vs Pub/Sub Lite is available at
https://cloud.google.com/pubsub/docs/choosing-pubsub-or-lite.

Complete sample programs can be found at
https://github.com/GoogleCloudPlatform/golang-samples/tree/master/pubsublite.

See https://pkg.go.dev/cloud.google.com/go for authentication, timeouts,
connection pooling and similar aspects of this package.
*/
package pscompat // import "cloud.google.com/go/pubsublite/pscompat"