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Building Compelling Applications Using the eBay API Platform

Posted by Bradburn Young in Developers Conference
Monday, Nov.16.2009, 1:27 PM PT

eBay is presenting some sessions here at the PayPal X Innovate 09 conference, and today, Rekha Patel of eBay gave her classic tutorial on how to get started creating applications using the eBay APIs. It's about the best introduction you can get to the eBay APIs. I humbly summarize.

Suppose you are a casual eBay seller, selling five to ten items a week, and you want to ramp up to sell thousands of items per week. Listing via the eBay website won't be scalable for you. You'll need the eBay APIs.

You can use the APIs to build widgets, gadgets, plugins, mobile applications, toolbars, and desktop and web applications. You can write these applications in any programming language that can sent HTTP requests. The applications can list items, manage inventory, find items, buy items, integrate with fulfillment systems, manage messages, manage user accounts, and perform and react to research about listings and transactions on eBay.

The APIs fall into four main groups:

Buying APIs

Finding
Shopping
Merchandising

Research and Data APIs

Price Research
Advanced Research

Selling APIs

Trading
Large Merchant Services
Feedback
Best Match
Selling Manager Applications

Monitoring APIs

Platform Notifications
Client Alerts

You can check them out and use them at developer.ebay.com.

Rekha did two live demos. The first was a simple demo that showed how to find and use public information on eBay. This operation used the new Finding service to get information on the price and availability of an item listed on eBay, and then to filter the results by location and price.

The second was more complicated, and showed how to use APIs on behalf of a user of your application, in ways that involve that user's private information and require that you have proof that you have that user's formal permission. Rekha showed the process of joining the eBay Developers Program, getting an application ID and keyset, creating a user in the eBay Sandbox, getting a token for the user using the eBay token tool, and linking that user to the application ID. You can do all of this in about ten minutes.

Having demonstrated that it's not that hard to get started writing eBay applications, Rekha closed with some design considerations for eBay applications:

Use the APIs that require the least amount of authorization. If you only want to do finding and research, you don't need to get user tokens to act on behalf of users.
Test in the Sandbox.
Implement retries in case of server errors.
Use best practices as given in the API documentation and the Knowledge Base.
Limit the data you process to what you need.
Implement logging, especially if you have a selling application.
Plan to renew user tokens before their expiration at 18 months.
Plan to update your application to the current eBay version about every six months.
Estimate your API call volume.
If you need more than 5,000 API calls per day, apply for a Compatible Application Check, which raises your application's call limit.