eBay Schema Versioning Strategy

As of February 2020, the lowest supported version is 1097.

This topic describes eBay's versioning strategy for the Trading API (and Shopping API), which enables us to evolve the schema while maintaining backward compatibility for at least 18 months. This strategy is intended to address these concerns:

• eBay adds new features every two weeks. If you update your client software less frequently, your software needs a way to handle unrecognized data from eBay.
• Over time, it becomes more difficult for eBay to support third-party software that is using outdated business logic or features. eBay needs a way to eventually drop support for outdated features.
• We understand that it may be difficult for you to update your software on short notice. To help you, eBay needs to maintain support for outdated features for some period of time, and we need to give you as much notice as possible before we completely stop supporting a feature.

In each release, we do our best to update the schema in a backward-compatible way. However, sometimes we need to make changes that aren't backward compatible:

• As XML schema constructs are typed, any modification that would result in a type change is a potential incompatibility. As a very simple example, we might currently express a measurement or a count in integer values (xs:int), but in a future enhancement we might need a way to allow decimal fractions for the same value (xs:double). If your application is expecting a field to return an integer at runtime and we start returning a double instead, your application could fail. So, we need a way to avoid changing the type directly.
• Changing the multiplicity of an element is also a potential incompatibility. For example, we might currently allow a single URL field, but in a future enhancement we might allow repeating URL fields (maxOccurs="unbounded"). As some toolkits interpret repeating fields as arrays, this would be equivalent to a type change.

When such changes are necessary, we need a way to gracefully phase in the new approach and gracefully phase out the old one. (That is, we need to make changes without causing third-party applications to fail unexpectedly, and applications need to be designed to accommodate routine changes.) This approach is described below.

Basic Schema Concepts
Versioning Strategy Key Points
eBay's Version Support Schedule
Schema Changes That Affect Compatibility
Logical Changes That Affect Compatibility
Schema Versions and Requirements for Compatible Application Check
Upgrading Applications to Support New Versions

Also see:

Version-Dependent Logical Changes

Basic Schema Concepts

Before reading this document, you should be familiar with these basic concepts.

Versioning Strategy Key Points

This section summarizes key points you should understand about our versioning strategy. These points are explained in more detail in later sections.

• Object Deprecation and Deletion:

  A deprecated object is an object that we no longer recommend. The schema version when this deprecation occurs is the object's deprecation version. For example, if we deprecated an object called "Flavor" in version 1161 of the schema, then the deprecation version for that object was 1161.

  Whenever we deprecate an object, we also delete the object from the latest schema at the same time (unless otherwise noted). Your application should not be affected by these deletions until you upgrade to a newer version of the schema. (See the object deprecation schedule for a list of previously deprecated objects that have been deleted from the schema.)

  We control a deprecated object's usage based on the request version:

  • If it's an input object, you may only receive a warning (regardless of the request version).
  • If it's an output object, we only return it with request versions that are lower than the deprecation version (unless otherwise noted).
  • If it was deprecated earlier than the lowest supported version (see below), it will no longer work.

  See Deprecation of Existing Objects for more details.

• Lowest Supported Version:

  We increment the lowest supported version every 6 months. The lowest supported version will be 18 months old. See eBay's Version Support Schedule.
  
  Objects that were deprecated in unsupported versions (more than 18 months old) may no longer work, or may stop working without notice. Applications should remove dependencies on deprecated objects as early as possible.

eBay's Version Support Schedule

In February and August of each year, eBay increments the lowest supported schema version.

The table below shows eBay's schema version support schedule. The row with bold text indicates the current lowest supported version. Rows with gray text indicate future versions that are not yet published or past versions that are no longer supported.

Version Support Schedule (Projected)

Here's an example of how to interpret the table:

• As of February 2020, the lowest version guaranteed to be supported is 1097.
• In August 2020, we increment the lowest supported version to 1123.
• If you upgrade to version 1097, before August 2020, you would be able to use 1097 until August 2020 (when the lowest supported version moves to 1123).

Here's how this schedule will affect you:

• If your application is using a version lower than the lowest supported version, you should upgrade your software to use a supported version. You are encouraged to use one of the most recent versions available.
• If you are creating a new application, you are required to use the latest version available.

Important: Once a schema version is no longer supported, objects that were deprecated as of that version (or earlier) are not supported, regardless of the request version.

Schema Changes That Affect Compatibility

eBay makes three basic kinds of changes to the schema:

• We add new objects.
• We deprecate existing objects.
• We replace existing objects or change their type.

In many cases, these changes will not affect your application until you upgrade to a newer schema. The effects can depend on whether your application happens to use the functionality that has changed, and the version of the schema you are using.

We do our best to keep you informed of schema changes through the schema documentation, release notes, the eBay Developer Program Blog, site status, and other mechanisms.

Addition of New Objects

We can introduce new objects at any time and at any level of the schema.

Usually, the request version doesn't control your ability to use new elements or calls (unless otherwise noted). For example, new output elements are usually returned for all request versions. We add an xs:any element to the end of each type to express this openness. By policy we also try to add elements to the end of a type before the xs:any element. (This is only a policy; it's not a guarantee.)

However, the request version does control whether we return new code type values (enumerations) in responses. If your software is already using an element that is a code type, you need a safe way to handle new values that your software doesn't recognize yet. Therefore, we check your request version, and then in our response we map any newer code type values to a default value you can recognize (CustomCode) instead. (See Overview of the API Schema for more information about code types.)

For backward compatibility:

• You should design your software to be able to handle or gracefully ignore extra elements that we add to the schema. For example, at any time, API calls may return new elements in addition those declared in the version of the schema you are using.
• Your software should also be prepared to see and handle "CustomCode" (without quotes) for values that we have added to code types in versions that are newer than your current request version.

Deprecation of Existing Objects

As stated earlier, a deprecated object is an object that we no longer recommend (although we still support it). We do our best not to deprecate objects, but sometimes it becomes necessary to deprecate an object due to business, legal, or functional issues. The schema version when this deprecation occurs is the object's deprecation version.

Here's what happens in the API:

• When we deprecate an object, we delete it from the schema at the same time. (If your application already uses the object, you should not be affected until you upgrade to the deprecation version or higher.)
• When we increment the lowest supported schema version, we will drop support for all objects that were deprecated in lower versions. See eBay's Version Support Schedule.

Here's the behavior you can expect:

• Your application should not be affected by newly deleted objects as long as you are using good coding practices. For example, you should not hard-code a check for, say, "the 20th element" in the response.
• For backward compatibility, how you use a deprecated object depends on whether the object is in the request (input) or the response (output). The policy in the table below assumes that the deprecation version and your request version are both supported (i.e., greater than the lowest supported version).

When testing a call, you can set WarningLevel to High to identify whether you are using deprecated objects in your request.

Replacements and Type Changes

We sometimes need to effectively change an existing object to a different type, or replace or rename an object. Rather than replacing an object directly, we usually use the addition and deprecation approaches described above. That is, we add a new object with a different name and we deprecate the old object.

For backward compatibility:

• Treat the new object like any other new object. It will be available regardless of the request version (unless otherwise noted). See Addition of New Objects above.
• Treat the old object like any other deprecated object. See Deprecation of Existing Objects above.

Client software that depends on the old object should start using (or expecting) the new one as soon as possible. This is particularly important if the old object reflects functionality that is inconsistent with current eBay site logic. Otherwise, your application's users may see unexpected (and undesirable) behavior.

In some cases, we may change an existing object's behavior without replacing it. See Logical Changes That Affect Compatibility for an example. Again, we do our best to minimize these kinds of changes.

Logical Changes That Affect Compatibility

Incompatible changes can be logical or functional; not necessarily changes to the schema itself. As with deprecated objects, we implement these kinds of changes based on the version whenever possible.

For example, suppose a call returns a node called ManyDetails:

• In version 483, we always return ManyDetails.
• In version 503, we add a new IncludeManyDetails field to the request, and we set the default to false (so that ManyDetails is only returned when you specifically ask for it).

In this example, we are not deprecating ManyDetails or changing the schema in any way, but this change would break any application that specifically looks for ManyDetails and expects it to be returned by default. Therefore, we would implement this change so that only clients specifying request version 503 or higher would see the new behavior.

See the Version-Dependent Logical Changes table for a summary of objects that behave differently based on the request version.

Schema Versions and Requirements for Compatible Application Check

To comply with eBay's requirements for Compatible Application Check, new applications must use the latest version that is available in the Production environment at the time of Compatible Application Check.

For example, suppose your application had a Compatible Application Check at version 525. If version 555 is the latest version available in production, then you can still use version 525 or higher.

On the other hand, suppose you submit a new request for a Compatible Application Check. If version 555 is the latest version available in production, you would need to use the latest version (555 in this example).

We increment the lowest supported version periodically. Make sure you understand how your application will be affected by these changes (see eBay's Version Support Schedule). Plan to start adjusting your application to use the latest version before we drop support for the version you are using. (You do not necessarily need to redo a Compatible Application Check for your application if you are only upgrading it to a newer version.)

Upgrading Applications to Support New Versions

At a high level, we suggest you follow this process when you upgrade an application to a newer version of the schema:

1. Make sure the application uses no invalid objects or functionality. For example:
   • For each call, remove dependencies on objects that have been deprecated for the version you are upgrading to.
   • For each call, make sure the request only includes applicable and valid fields. For example, certain fields that are valid in AddItem calls may be invalid in ReviseItem calls.
2. Use the Sandbox to test your application's compatibility with the new version.
   • Make sure that all requests trigger no warnings or errors.
   • Set WarningLevel to High to make sure no schema warnings are returned.

FAQs

What is a Compatibility Level?

You may see some people use the older term "compatibility level" instead of "request version" in the Forums, KB articles, obsolete documentation, and other resources. The term is also used in the X-EBAY-API-COMPATIBILITY-LEVEL header, for XML requests. This is simply an older name for the request version.