samples: add schema samples (#306)

* samples: create, delete, get, list samples

* add publish and subscribe with avro schema samples

* add publish and subscribe with proto schema samples

* add protoc compiled class

* address leah's and peter's comments

* avoid using google.auth.default() for testing

* use choice in argparse

* update python to python3 in readme

samples/snippets/README.rst

@@ -78,7 +78,7 @@ To run this sample:
 
 .. code-block:: bash
 
-    $ python quickstart/pub.py
+    $ python3 quickstart/pub.py
 
 
 Quickstart (Subscriber)
@@ -94,7 +94,7 @@ To run this sample:
 
 .. code-block:: bash
 
-    $ python quickstart/sub.py
+    $ python3 quickstart/sub.py
 
 
 Publisher
@@ -110,7 +110,7 @@ To run this sample:
 
 .. code-block:: bash
 
-    $ python publisher.py
+    $ python3 publisher.py
 
     usage: publisher.py [-h]
                         project_id
@@ -168,7 +168,7 @@ To run this sample:
 
 .. code-block:: bash
 
-    $ python subscriber.py
+    $ python3 subscriber.py
 
     usage: subscriber.py [-h]
                          project_id
@@ -232,7 +232,7 @@ To run this sample:
 
 .. code-block:: bash
 
-    $ python iam.py
+    $ python3 iam.py
 
     usage: iam.py [-h]
                   project_id
@@ -266,6 +266,48 @@ To run this sample:
 
 
 
+Schema
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+
+.. image:: https://gstatic.com/cloudssh/images/open-btn.png
+   :target: https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com//googleapis/python-pubsub&page=editor&open_in_editor=samples/snippets/schema.py,samples/snippets/README.rst
+
+
+
+
+To run this sample:
+
+.. code-block:: bash
+
+    $ python3 schema.py
+
+    usage: schema.py [-h]
+                    project_id
+                    {create-avro,create-proto,get,list,delete,create-topic,publish-avro,publish-proto,receive-avro,receive-proto}
+                    ...
+
+    This application demonstrates how to perform basic schema operations
+    using the Cloud Pub/Sub API.
+
+    For more information, see the README.md under /pubsub and the documentation
+    at https://cloud.google.com/pubsub/docs.
+
+    positional arguments:
+    project_id            Your Google Cloud project ID
+    {create-avro,create-proto,get,list,delete,create-topic,publish-avro,publish-proto,receive-avro,receive-proto}
+        create-avro         Create a schema resource from an Avro schema file formatted in JSON.
+        create-proto        Create a schema resource from a protobuf schema file.
+        get                 Get a schema resource.
+        list                List schema resources.
+        delete              Delete a schema resource.
+        create-topic        Create a topic resource with a schema.
+        publish-avro        Pulbish a BINARY or JSON encoded message to a topic configured with an Avro schema.
+        publish-proto       Publish a BINARY or JSON encoded message to a topic configured with a protobuf schema.
+        receive-avro        Receive and decode messages sent to a topic with an Avro schema.
+        receive-proto       Receive and decode messages sent to a topic with a protobuf schema.
+
+    optional arguments:
+    -h, --help            show this help message and exit
 
 
 The client library

samples/snippets/requirements.txt

@@ -1 +1,2 @@
 google-cloud-pubsub==2.4.0
+avro==1.10.1

samples/snippets/resources/us-states.avsc

@@ -0,0 +1,18 @@
+{
+  "type":"record",
+  "name":"State",
+  "namespace":"utilities",
+  "doc":"A list of states in the United States of America.",
+  "fields":[
+    {
+      "name":"name",
+      "type":"string",
+      "doc":"The common name of the state."
+    },
+    {
+      "name":"post_abbr",
+      "type":"string",
+      "doc":"The postal code abbreviation of the state."
+    }
+  ]
+}

samples/snippets/resources/us-states.proto

@@ -0,0 +1,8 @@
+syntax = "proto3";
+
+package utilities;
+
+message StateProto {
+  string name = 1;
+  string post_abbr = 2;
+}