feat(examples): Add example for service accounts + Cloud Pubsub

Please note that I specified version 0.9.4 in the example crate
(anticipating the version bump)

examples/service_account/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "service_account"
+version = "0.1.0"
+authors = ["Lewin Bormann <lewin@lewin-bormann.info>"]
+
+[dependencies]
+base64 = "0.2"
+yup-oauth2 = "0.6.4"
+google-pubsub1 = { version = "0.1", path = "../../../google-apis-rs/gen/pubsub1" }
+hyper = "0.9"

examples/service_account/pubsub-auth.json

@@ -0,0 +1,12 @@
+{
+  "type": "service_account",
+  "project_id": "sanguine-rhythm-105020",
+  "private_key_id": "bbd866b207d9081b56d6cdce09782bcc5cc7b55b",
+  "private_key": "-----BEGIN PRIVATE KEY-----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\nvBj5QAMZDCn/3qeOpGJ1NJo=\n-----END PRIVATE KEY-----\n",
+  "client_email": "pubsub-1@sanguine-rhythm-105020.iam.gserviceaccount.com",
+  "client_id": "117880612788657019000",
+  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
+  "token_uri": "https://accounts.google.com/o/oauth2/token",
+  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
+  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/pubsub-1%40sanguine-rhythm-105020.iam.gserviceaccount.com"
+}

examples/service_account/src/main.rs

@@ -0,0 +1,183 @@
+//! Demonstrates the use of service accounts and the Google Cloud Pubsub API.
+//!
+//! Run this binary as .../service_account pub 'your message' in order to publish messages,
+//! and as .../service_account sub in order to subscribe to those messages. This will look like the
+//! following:
+//!
+//! ```
+//! $ target/debug/service_account pub 'Hello oh wonderful world' &
+//! $ target/debug/service_account sub
+//! Published message #95491011619126
+//! message <95491011619126> 'Hello oh wonderful world' at 2016-09-21T20:04:47.040Z
+//! Published message #95491011620879
+//! message <95491011620879> 'Hello oh wonderful world' at 2016-09-21T20:04:49.086Z
+//! Published message #95491011622600
+//! message <95491011622600> 'Hello oh wonderful world' at 2016-09-21T20:04:51.132Z
+//! Published message #95491011624393
+//! message <95491011624393> 'Hello oh wonderful world' at 2016-09-21T20:04:53.187Z
+//! Published message #95491011626206
+//! message <95491011626206> 'Hello oh wonderful world' at 2016-09-21T20:04:55.233Z
+//!
+//! Copyright (c) 2016 Google, Inc. (Lewin Bormann <lbo@spheniscida.de>)
+//!
+extern crate base64;
+extern crate yup_oauth2 as oauth;
+extern crate google_pubsub1 as pubsub;
+extern crate hyper;
+
+use std::env;
+use std::time;
+use std::thread;
+
+use pubsub::{Topic, Subscription};
+
+// The prefixes are important!
+const SUBSCRIPTION_NAME: &'static str = "projects/sanguine-rhythm-105020/subscriptions/rust_authd_sub_1";
+const TOPIC_NAME: &'static str = "projects/sanguine-rhythm-105020/topics/topic-01";
+
+type PubsubMethods<'a> = pubsub::ProjectMethods<'a,
+                                                hyper::Client,
+                                                oauth::ServiceAccountAccess<hyper::Client>>;
+
+// Verifies that the topic TOPIC_NAME exists, or creates it.
+fn check_or_create_topic(methods: &PubsubMethods) -> Topic {
+    let result = methods.topics_get(TOPIC_NAME).doit();
+
+    if result.is_err() {
+        println!("Assuming topic doesn't exist; creating topic");
+        let topic = pubsub::Topic { name: Some(TOPIC_NAME.to_string()) };
+        let result = methods.topics_create(topic, TOPIC_NAME).doit().unwrap();
+        result.1
+    } else {
+        result.unwrap().1
+    }
+}
+
+fn check_or_create_subscription(methods: &PubsubMethods) -> Subscription {
+    // check if subscription exists
+    let result = methods.subscriptions_get(SUBSCRIPTION_NAME).doit();
+
+    if result.is_err() {
+        println!("Assuming subscription doesn't exist; creating subscription");
+        let sub = pubsub::Subscription {
+            topic: Some(TOPIC_NAME.to_string()),
+            ack_deadline_seconds: Some(30),
+            push_config: None,
+            name: Some(SUBSCRIPTION_NAME.to_string()),
+        };
+        let (_resp, sub) = methods.subscriptions_create(sub, SUBSCRIPTION_NAME).doit().unwrap();
+
+        sub
+    } else {
+        result.unwrap().1
+    }
+}
+
+fn ack_message(methods: &PubsubMethods, id: String) {
+    let request = pubsub::AcknowledgeRequest { ack_ids: Some(vec![id]) };
+    let result = methods.subscriptions_acknowledge(request, SUBSCRIPTION_NAME).doit();
+
+    match result {
+        Err(e) => {
+            // There's a JSON decode error happening, even on successful returns. :/
+            println!("Ack error: {:?}", e);
+        }
+        Ok(_) => (),
+    }
+}
+
+// Wait for new messages. Print and ack any new messages.
+fn subscribe_wait(methods: &PubsubMethods) {
+    check_or_create_subscription(&methods);
+
+    let request = pubsub::PullRequest {
+        return_immediately: Some(false),
+        max_messages: Some(1),
+    };
+
+
+    loop {
+        let result = methods.subscriptions_pull(request.clone(), SUBSCRIPTION_NAME).doit();
+
+        match result {
+            Err(e) => {
+                println!("Pull error: {}", e);
+            }
+            Ok((_response, pullresponse)) => {
+                for msg in pullresponse.received_messages.unwrap_or(Vec::new()) {
+                    let ack_id = msg.ack_id.unwrap_or(String::new());
+                    let message = msg.message.unwrap_or(Default::default());
+                    println!("message <{}> '{}' at {}",
+                             message.message_id.unwrap_or(String::new()),
+                             String::from_utf8(base64::decode(&message.data
+                                         .unwrap_or(String::new()))
+                                     .unwrap())
+                                 .unwrap(),
+                             message.publish_time.unwrap_or(String::new()));
+
+                    if ack_id != "" {
+                        ack_message(methods, ack_id);
+                    }
+                }
+            }
+        }
+    }
+}
+
+// Publish some message every 2 seconds.
+fn publish_stuff(methods: &PubsubMethods, message: &str) {
+    check_or_create_topic(&methods);
+
+    let message = pubsub::PubsubMessage {
+        attributes: None,
+        // Base64 encoded!
+        data: Some(base64::encode(message.as_bytes())),
+        publish_time: None,
+        message_id: None,
+    };
+    let request = pubsub::PublishRequest { messages: Some(vec![message]) };
+
+
+    loop {
+        let result = methods.topics_publish(request.clone(), TOPIC_NAME).doit();
+
+        match result {
+            Err(e) => {
+                println!("Publish error: {}", e);
+            }
+            Ok((_response, pubresponse)) => {
+                for msg in pubresponse.message_ids.unwrap_or(Vec::new()) {
+                    println!("Published message #{}", msg);
+                }
+            }
+        }
+
+        thread::sleep(time::Duration::new(2, 0));
+    }
+}
+
+// If called as '.../service_account pub', act as publisher; if called as '.../service_account
+// sub', act as subscriber.
+fn main() {
+    let client_secret = oauth::service_account_key_from_file(&"pubsub-auth.json".to_string())
+        .unwrap();
+    let mut access = oauth::ServiceAccountAccess::new(client_secret, hyper::Client::new());
+
+    use oauth::GetToken;
+    println!("{:?}",
+             access.token(&vec!["https://www.googleapis.com/auth/pubsub"]).unwrap());
+
+    let hub = pubsub::Pubsub::new(hyper::Client::new(), access);
+    let methods = hub.projects();
+
+    let mode = env::args().nth(1).unwrap_or(String::new());
+
+    if mode == "pub" {
+        let message = env::args().nth(2).unwrap_or("Hello World!".to_string());
+        publish_stuff(&methods, &message);
+    } else if mode == "sub" {
+        subscribe_wait(&methods);
+    } else {
+        println!("Please use either of 'pub' or 'sub' as first argument to this binary!");
+    }
+}