Improve READMEs for App Engine samples.

These are linked to from https://cloud.google.com/java/, so we should
have a more welcoming landing page than the existing list of folders.

appengine/README.md

@@ -0,0 +1,101 @@
+# Google App Engine Standard Environment Java Samples
+
+This is a repository that contains Java code samples for [Google App Engine
+standard environment][ae-docs].
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+
+## Prerequisites
+
+### Download Maven
+
+These samples use the [Apache Maven][maven] build system. Before getting
+started, be sure to [download][maven-download] and [install][maven-install] it.
+When you use Maven as described here, it will automatically download the needed
+client libraries.
+
+[maven]: https://maven.apache.org
+[maven-download]: https://maven.apache.org/download.cgi
+[maven-install]: https://maven.apache.org/install.html
+
+### Create a Project in the Google Cloud Platform Console
+
+If you haven't already created a project, create one now. Projects enable you to
+manage all Google Cloud Platform resources for your app, including deployment,
+access control, billing, and services.
+
+1. Open the [Cloud Platform Console][cloud-console].
+1. In the drop-down menu at the top, select **Create a project**.
+1. Give your project a name.
+1. Make a note of the project ID, which might be different from the project
+   name. The project ID is used in commands and in configurations.
+
+[cloud-console]: https://console.cloud.google.com/
+
+
+## Samples
+
+### Hello World
+
+This sample demonstrates how to deploy an application on Google App Engine.
+
+- [Documentation][ae-docs]
+- [Code](helloworld)
+
+### Sending Email
+
+#### Sending Email with Mailgun
+
+This sample demonstrates how to send email using the [Mailgun API][mailgun-api].
+
+- [Documentation][mailgun-sample-docs]
+- [Code](mailgun)
+
+[mailgun-api]: https://documentation.mailgun.com/
+[mailgun-sample-docs]: https://cloud.google.com/appengine/docs/java/mail/mailgun
+
+#### Sending Email with SendGrid
+
+This sample demonstrates how to send email using the [SendGrid][sendgrid].
+
+- [Documentation][sendgrid-sample-docs]
+- [Code](sendgrid)
+
+[sendgrid]: https://sendgrid.com/docs/User_Guide/index.html
+[sendgrid-sample-docs]: https://cloud.google.com/appengine/docs/java/mail/sendgrid
+
+### Sending SMS with Twilio
+
+This sample demonstrates how to use [Twilio](https://www.twilio.com) on [Google
+App Engine standard environment][ae-docs].
+
+- [Documentation][twilio-sample-docs]
+- [Code](twilio)
+
+[twilio-sample-docs]: https://cloud.google.com/appengine/docs/java/sms/twilio
+
+### App Identity
+
+This sample demonstrates how to use the [App Identity API][appid] to discover
+the application's ID and assert identity to Google and third-party APIs.
+
+- [Documentation][appid]
+- [Code](appidentity)
+
+[appid]: https://cloud.google.com/appengine/docs/java/appidentity/
+
+### Other Samples
+
+- [Sample Applications][sample-apps]
+
+[sample-apps]: https://cloud.google.com/appengine/docs/java/samples
+
+
+## Contributing changes
+
+See [CONTRIBUTING.md](../CONTRIBUTING.md).
+
+## Licensing
+
+See [LICENSE](../LICENSE).
+

appengine/appidentity/README.md

@@ -1,5 +1,10 @@
 # App Identity sample for Google App Engine
-This sample demonstrates how to use the App Identity APIs on Google App Engine
+
+This sample demonstrates how to use the [App Identity API][appid] on [Google App
+Engine][ae-docs].
+
+[appid]: https://cloud.google.com/appengine/docs/java/appidentity/
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
 
 ## Running locally
 This example uses the

appengine/helloworld/README.md

@@ -1,8 +1,17 @@
-# Appengine Helloworld sample for Google App Engine
-This sample demonstrates how to deploy an application on Google App Engine
+# Google App Engine Standard Environment Hello World Sample
+
+This sample demonstrates how to deploy an application on Google App Engine.
+
+See the [Google App Engine standard environment documentation][ae-docs] for more
+detailed instructions.
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+
 ## Setup
-1. Update the <application> tag in src/main/webapp/WEB-INF/appengine-web.xml with your project name
-1. Update the <version> tag in src/main/webapp/WEB-INF/appengine-web.xml with your version name
+1. Update the `<application>` tag in `src/main/webapp/WEB-INF/appengine-web.xml`
+   with your project name.
+1. Update the `<version>` tag in `src/main/webapp/WEB-INF/appengine-web.xml`
+   with your version name.
 
 ## Running locally
     $ mvn appengine:devserver

appengine/mailgun/README.md

@@ -0,0 +1,11 @@
+# Java Mailgun Email Sample for Google App Engine Standard Environment
+
+This sample demonstrates how to use [Mailgun][mailgun-api] on [Google App Engine
+standard environment][ae-docs].
+
+See the [sample application documentaion][sample-docs] for more detailed
+instructions.
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+[mailgun-api]: https://documentation.mailgun.com/
+[sample-docs]: https://cloud.google.com/appengine/docs/java/mail/mailgun

appengine/sendgrid/README.md

@@ -1,13 +1,31 @@
-# Java SendGrid email sample for Google Managed VMs
-This sample demonstrates how to use [SendGrid](https://www.sendgrid.com) on Google Managed VMs
-For more information about SendGrid, see their [documentation](https://sendgrid.com/docs/User_Guide/index.html).
+# Java SendGrid Email Sample for Google App Engine Standard Environment
+
+This sample demonstrates how to use [SendGrid](https://www.sendgrid.com) on
+[Google App Engine standard environment][ae-docs].
+
+See the [sample application documentaion][sample-docs] for more detailed
+instructions.
+
+For more information about SendGrid, see their
+[documentation](https://sendgrid.com/docs/User_Guide/index.html).
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+[sample-docs]: https://cloud.google.com/appengine/docs/java/mail/sendgrid
+
 ## Setup
+
 Before you can run or deploy the sample, you will need to do the following:
-1. [Create a SendGrid Account](http://sendgrid.com/partner/google). As of September 2015, Google users start with 25,000 free emails per month.
-1. Configure your SendGrid settings in the environment variables section in ``src/main/appengine/app.yaml``.
+
+1. [Create a SendGrid Account](http://sendgrid.com/partner/google). As of
+   September 2015, Google users start with 25,000 free emails per month.
+1. Configure your SendGrid settings in the environment variables section in
+   [`src/main/webapp/WEB-INF/appengine-web.xml`](src/main/webapp/WEB-INF/appengine-web.xml).
+
 ## Running locally
+
 You can run the application locally and send emails from your local machine. You
 will need to set environment variables before starting your application:
+
     $ export SENDGRID_API_KEY=[your-sendgrid-api-key]
     $ export SENDGRID_SENDER=[your-sendgrid-sender-email-address]
     $ mvn clean jetty:run

appengine/twilio/README.md

@@ -1,16 +1,36 @@
-# Java Twilio voice and SMS sample for Google Managed VMs
-This sample demonstrates how to use [Twilio](https://www.twilio.com) on Google Managed VMs
-For more information about Twilio, see their [Java quickstart tutorials](https://www.twilio.com/docs/quickstart/java).
+# Java Twilio Voice and SMS Sample for Google App Engine Standard Environment
+
+This sample demonstrates how to use [Twilio](https://www.twilio.com) on [Google
+App Engine standard environment][ae-docs].
+
+See the [sample application documentaion][sample-docs] for more detailed
+instructions.
+
+For more information about Twilio, see their [Java quickstart
+tutorials](https://www.twilio.com/docs/quickstart/java).
+
+[ae-docs]: https://cloud.google.com/appengine/docs/java/
+[sample-docs]: https://cloud.google.com/appengine/docs/java/sms/twilio
+
+
 ## Setup
+
 Before you can run or deploy the sample, you will need to do the following:
-1. [Create a Twilio Account](http://ahoy.twilio.com/googlecloudplatform). Google App Engine
-customers receive a complimentary credit for SMS messages and inbound messages.
-1. Create a number on twilio, and configure the voice request URL to be ``https://your-app-id.appspot.com/call/receive``
-and the SMS request URL to be ``https://your-app-id.appspot.com/sms/receive``.
-1. Configure your Twilio settings in the environment variables section in ``src/main/appengine/app.yaml``.
+
+1. [Create a Twilio Account](http://ahoy.twilio.com/googlecloudplatform). Google
+   App Engine customers receive a complimentary credit for SMS messages and
+   inbound messages.
+1. Create a number on twilio, and configure the voice request URL to be
+   ``https://your-app-id.appspot.com/call/receive`` and the SMS request URL to
+   be ``https://your-app-id.appspot.com/sms/receive``.
+1. Configure your Twilio settings in the environment variables section in
+   [`src/main/webapp/WEB-INF/appengine-web.xml`](src/main/webapp/WEB-INF/appengine-web.xml).
+
 ## Running locally
+
 You can run the application locally to test the callbacks and SMS sending. You
 will need to set environment variables before starting your application:
+
     $ export TWILIO_ACCOUNT_SID=[your-twilio-accoun-sid]
     $ export TWILIO_AUTH_TOKEN=[your-twilio-auth-token]
     $ export TWILIO_NUMBER=[your-twilio-number]

managed_vms/README.md

@@ -1,11 +1,14 @@
-## Google Managed VMs Java Samples
+# Google App Engine Flexible Environment Java Samples
 
-This is a repository that contains Java code samples for Google Managed VMs
+This is a repository that contains Java code samples for [Google App Engine
+flexible environment][aeflex-docs].
 
-See our other [Google Cloud Platform github
+See our other [Google Cloud Platform GitHub
 repos](https://github.com/GoogleCloudPlatform) for sample applications and
 scaffolding for other frameworks and use cases.
 
+[aeflex-docs]: https://cloud.google.com/appengine/docs/flexible/
+
 ## Run Locally
 1. Install the [Google Cloud SDK](https://cloud.google.com/sdk/), including the [gcloud tool](https://cloud.google.com/sdk/gcloud/), and [gcloud app component](https://cloud.google.com/sdk/gcloud-app).
 1. Setup the gcloud tool.
@@ -17,7 +20,7 @@ scaffolding for other frameworks and use cases.
 1. Clone this repo.
 
    ```
-   git clone https://github.com/GoogleCloudPlatform/<REPO NAME>.git
+   git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git
    ```
 
 1. Run this project locally from the command line.

managed_vms/sendgrid/README.md

@@ -1,13 +1,31 @@
-# Java SendGrid email sample for Google Managed VMs
-This sample demonstrates how to use [SendGrid](https://www.sendgrid.com) on Google Managed VMs
-For more information about SendGrid, see their [documentation](https://sendgrid.com/docs/User_Guide/index.html).
+# Java SendGrid Email Sample for Google App Engine Flexible Environment
+
+This sample demonstrates how to use [SendGrid](https://www.sendgrid.com) on
+[Google App Engine flexible environment][aeflex-docs].
+
+See the [sample application documentaion][sample-docs] for more detailed
+instructions.
+
+For more information about SendGrid, see their
+[documentation](https://sendgrid.com/docs/User_Guide/index.html).
+
+[aeflex-docs]: https://cloud.google.com/appengine/docs/flexible/
+[sample-docs]: https://cloud.google.com/appengine/docs/flexible/java/sending-emails-with-sendgrid
+
 ## Setup
+
 Before you can run or deploy the sample, you will need to do the following:
-1. [Create a SendGrid Account](http://sendgrid.com/partner/google). As of September 2015, Google users start with 25,000 free emails per month.
-1. Configure your SendGrid settings in the environment variables section in ``src/main/appengine/app.yaml``.
+
+1. [Create a SendGrid Account](http://sendgrid.com/partner/google). As of
+   September 2015, Google users start with 25,000 free emails per month.
+1. Configure your SendGrid settings in the environment variables section in
+   [`src/main/appengine/app.yaml`](src/main/appengine/app.yaml).
+
 ## Running locally
+
 You can run the application locally and send emails from your local machine. You
 will need to set environment variables before starting your application:
+
     $ export SENDGRID_API_KEY=[your-sendgrid-api-key]
     $ export SENDGRID_SENDER=[your-sendgrid-sender-email-address]
     $ mvn clean jetty:run

managed_vms/twilio/README.md

@@ -1,16 +1,36 @@
-# Java Twilio voice and SMS sample for Google Managed VMs
-This sample demonstrates how to use [Twilio](https://www.twilio.com) on Google Managed VMs
-For more information about Twilio, see their [Java quickstart tutorials](https://www.twilio.com/docs/quickstart/java).
+# Java Twilio Voice and SMS Sample for Google App Engine Flexible Environment
+
+This sample demonstrates how to use [Twilio](https://www.twilio.com) on [Google
+App flexible environment][aeflex-docs].
+
+See the [sample application documentaion][sample-docs] for more detailed
+instructions.
+
+For more information about Twilio, see their [Java quickstart
+tutorials](https://www.twilio.com/docs/quickstart/java).
+
+[aeflex-docs]: https://cloud.google.com/appengine/docs/flexible/
+[sample-docs]: https://cloud.google.com/appengine/docs/flexible/java/using-sms-and-voice-services-via-twilio
+
+
 ## Setup
+
 Before you can run or deploy the sample, you will need to do the following:
-1. [Create a Twilio Account](http://ahoy.twilio.com/googlecloudplatform). Google App Engine
-customers receive a complimentary credit for SMS messages and inbound messages.
-1. Create a number on twilio, and configure the voice request URL to be ``https://your-app-id.appspot.com/call/receive``
-and the SMS request URL to be ``https://your-app-id.appspot.com/sms/receive``.
-1. Configure your Twilio settings in the environment variables section in ``src/main/appengine/app.yaml``.
+
+1. [Create a Twilio Account](http://ahoy.twilio.com/googlecloudplatform). Google
+   App Engine customers receive a complimentary credit for SMS messages and
+   inbound messages.
+1. Create a number on twilio, and configure the voice request URL to be
+   ``https://your-app-id.appspot.com/call/receive`` and the SMS request URL to
+   be ``https://your-app-id.appspot.com/sms/receive``.
+1. Configure your Twilio settings in the environment variables section in
+   ``src/main/appengine/app.yaml``.
+
 ## Running locally
+
 You can run the application locally to test the callbacks and SMS sending. You
 will need to set environment variables before starting your application:
+
     $ export TWILIO_ACCOUNT_SID=[your-twilio-accoun-sid]
     $ export TWILIO_AUTH_TOKEN=[your-twilio-auth-token]
     $ export TWILIO_NUMBER=[your-twilio-number]