The web publication of an Apps Script has two general steps. First, version management must be established before the Apps Script environment allows a script to be published. To initiate managed version control, click on File | Manage Versions… from the menu bar. In the Manage Versions window, enter a description of the version and click on Save New Version. The current script version will then be saved as a snapshot in time, and can be called on by other script projects. It can also be loaded as a particular instance of the published script.

When at least one version is available, the Apps Script environment will allow a web instance to be published. From the menu bar, click on Publish | Deploy as web app… to deploy the script as a web page.

Alternatively, selecting the cloud arrow button from the menu bar also accesses the Deploy as web app... window.

In the Deploy as web app window click on the script version that is to be deployed. The versions available are the same versions as saved in the Manage Versions… window. Next, select the level of access for the new web application. The Execute this app as: option tells the application under which user permissions to run the application. This setting is important because allowing a user to run as script developer allows the user to perform the same actions for which the developer has rights. However, certain normal actions in an application may require elevated permissions, thus potentially prohibiting the functionality of the script.

The Who has access to the app: setting is slightly more self-explanatory. This setting simply determines if web users can view the script application or if it is private to the developer.

Recall that designing an Apps Script that creates a visualization in a Spreadsheet requires programming specific to the Spreadsheet interface itself (see Chapter 4, Basic Charts). The result of this specification generally means an Apps Script attached to a Spreadsheet has a high chance of failing to translate into a standalone web page. Apps Scripts attached to a Spreadsheet are still fully functional and have the potential to stand alone as a web app, but any code referencing an interaction with the Spreadsheet must first be removed.

The Google Development SDK provides the basic functionality needed to test and launch an application in App Engine. It is intended for use by developers fluent in Java, Python, or Google's own programming language, Go. A consequence of using the SDK method to publish API Visualizations is that there is some overhead programming required to create a Java, Python, or Go framework to serve HTTP pages. App Engine applications do however use the standard WAR structure for bundling web applications, making it possible to manually create an application folder structure.

In this method, testing and deploying the application is accomplished through the SDK command line or with the GoogleAppEngineLauncher tool.

If developing in an environment such as Eclipse, use the Google plugin for Eclipse. The plugin provides basic framework templates that are accessed as App Engine projects directly from Eclipse. Deployment of an App Engine application in Eclipse is as simple as with the Google plugin. After installing the plugin through the Eclipse add software method, create or deploy an App Engine application in Eclipse, and click on the icon in the menu bar. From the drop-down menu, select the appropriate action desired.

For a new web project, the project initialization and configuration steps will look very similar to all other Eclipse project creation wizards.

Possibly the most intuitive method of App Engine development is to use a cloud-based online development environment for which application deployment to App Engine is integrated. This approach allows for template-based deployment of App Engine apps as well as faster testing and update processes. Cloud 9 IDE (Integrated Development Environment) and Codenvy IDE are two popular cloud-hosted development environments available at the time of this book's publication. The Codenvy IDE is used in the following visualization API application example, with discussion of basic functionality as applied to launching visualization API applications in App Engine.

The Codenvy development application is fairly straightforward in organization. The menu bar is the primary access to environment functions. The folder structure of the application is on the left-hand side of the screen, with the selected file's contents displayed for editing on the right. The lower window and tabs display code previews and the output of environment operations, such as building and launching an application.

To create or update applications from the Codenvy IDE application, click on PaaS | Google App Engine from the menu bar. Choose either Update Application or Create Application… respectively.

The Codenvy application will then guide the developer through the App Engine creating an application process or automatically updating an existing application on App Engine.

Much of the development and deployment process for App Engine is handled through the IDE. However, independent of the development environment, App Engine applications must be initially created in the App Engine console. As mentioned earlier, the creation of the Application ID is required when configuring an application to deploy from any of the deployment.

In addition to the Visualization and Google Docs APIs, Google provides a selection of APIs for other Google services. While many of these APIs are available at no charge when consumed below a certain user threshold, heavier use requires a pay-for-what-you-use fee per API. To access additional APIs from Google, log in to the API Console. From the console, APIs can be turned on or off for a specific project.

Publishing a Google Visualization as a web page allows for a variety of development and deployment options. These options are also diverse across developer experience levels and workflows, which makes visualizations easy to incorporate in existing websites or as standalone pages.