Consume Gumroad OData Feeds in PowerBuilder

The CData API Server produces secure feeds of Gumroad data that you can consume in PowerBuilder DataWindows. The API Server supports the major Web services, including OData, Atom, JSON, HTML, CSV, TSV, and RSS. It also supports the major authentication schemes and SSL.

This article shows how to create a DataWindow that uses the CData API Server to retrieve data.

Set Up the API Server

Follow the steps below to begin producing secure Gumroad OData services:

Deploy

The API Server runs on your own server. On Windows, you can deploy using the stand-alone server or IIS. On a Java servlet container, drop in the API Server WAR file. See the help documentation for more information and how-tos.

The API Server is also easy to deploy on Microsoft Azure, Amazon EC2, and Heroku.

Connect to Gumroad

After you deploy the API Server, provide authentication values and other connection properties needed to connect to Gumroad by clicking Settings -> Connections and adding a new connection in the API Server administration console.

Using OAuth Authentication

To authenticate to Gumroad and connect to your own data or to allow other users to connect to their data, you can use the OAuth 2.0 standard. This is the recommended authentication method.

First you need to register an OAuth application with Gumroad. You can create an OAuth application by visiting your Gumroad account settings at https://app.gumroad.com/settings/advanced and navigating to the Applications section.

After setting the following connection properties, you are ready to connect:

• AuthScheme: Set this to OAuth.
• InitiateOAuth: Set this to GETANDREFRESH. The CData API Profile for Gumroad will automatically walk through the OAuth process in order to obtain the access token.
• OAuthClientID: Set this to the client_id that is specified in your app settings.
• OAuthClientSecret: Set this to the client_secret that is specified in your app settings.
• CallbackURL: Set this to the Redirect URI you specified in your app settings.

Example connection string

Profile=C:\profiles\Gumroad.apip;AuthScheme=OAuth;InitiateOAuth=GETANDREFRESH;OAuthClientId=your_client_id;OAuthClientSecret=your_client_secret;CallbackUrl=your_callback_url;

You can then choose the Gumroad entities you want to allow the API Server access to by clicking Settings -> Resources.

Additionally, click Settings -> Server and change the following settings for compatibility with PowerBuilder:

• Default Format: Select XML (Atom) in the menu.
• Default Version: Select 2.0 in the menu.

Authorize API Server Users

After determining the OData services you want to produce, authorize users by clicking Settings -> Users. The API Server uses authtoken-based authentication and supports the major authentication schemes. Access can also be restricted based on IP address; by default, only connections to the local machine are allowed. You can authenticate as well as encrypt connections with SSL.

Create a Profile for Gumroad

Follow the steps below to use the Database Painter tool to create a database profile for the OData API of the API Server. In the Database Painter, you can graphically manipulate data as well as execute SQL queries.

1. Click Tools -> Database Painter.
2. Right-click the OData node and click New Profile.
3. In the Database Profile Setup dialog, enter the following:
   • Profile Name: Enter a user-friendly name for the profile.
   • URI: Enter the URL to the OData endpoint of the API Server. This URL will resemble the one below:

     http://MyServer:8080/api.rsc

   • Supply User Id and Password: Click this option to use HTTP Basic authentication. Note that the API Server also supports Windows authentication.
   • User Id: Enter the name of an user in the API Server.
   • Password: Enter the authtoken of an user in the API Server.
   
4. To view and modify a table, right-click a table and then click Edit Data -> Grid.

Using Gumroad Data with PowerBuilder Controls

You can use standard PowerBuilder objects to connect to OData feeds and execute queries. The following example shows how to retrieve Gumroad data into a DataWindow.

You can add the following code to the open method:

SQLCA.DBMS = "ODT"
SQLCA.DBParm = "ConnectString='URI=http://MyServer:8080/api.rsc;UID=MyAPIUser;PWD=MyAuthtoken'";
CONNECT USING SQLCA;
dw_customfields.SetTransObject(SQLCA);
dw_customfields.Retrieve();