Use native Pub/Sub library primitives.

common/gcloud/pubsub/connection.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package pubsub
-
-import (
-        "golang.org/x/net/context"
-        "google.golang.org/cloud/pubsub"
-)
-
-var (
-        // PublisherScopes is the set of OAuth2 scopes needed for a publisher to
-        // publish messages.
-        PublisherScopes = []string{
-                pubsub.ScopePubSub,
-        }
-
-        // SubscriberScopes is the set of OAuth2 scopes needed for a subscriber to
-        // pull and acknowledge messages.
-        SubscriberScopes = []string{
-                pubsub.ScopePubSub,
-        }
-)
-
-// Connection is an interface to a Pub/Sub connection.
-//
-// Any method may return an errors.TransientError to indicate that the
-// encountered error was transient.
-type Connection interface {
-        // TopicExists tests if a given Topic exists.
-        TopicExists(context.Context, Topic) (bool, error)
-
-        // SubscriptionExists tests if a given Subscription exists.
-        SubExists(context.Context, Subscription) (bool, error)
-
-        // Publish publishes a batch of Pub/Sub messages.
-        Publish(context.Context, Topic, ...*Message) ([]string, error)
-
-        // Pull pulls messages from the subscription. It returns up the requested
-        // number of messages.
-        Pull(context.Context, Subscription, int) ([]*Message, error)
-
-        // Ack acknowledges one or more Pub/Sub message ACK IDs.
-        Ack(context.Context, Subscription, ...string) error
-}