InvalidateCache policy

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Configures how the cached values should be purged from the cache.

This policy is intended for use in general purpose short-term caching. It is used in conjunction with the Populate Cache policy (for writing entries) and the Lookup Cache policy (for reading cache entries).

For caching the responses of backend resources, see the Response Cache policy.

Element reference

The following lists the elements you can configure on this policy.

<InvalidateCache async="false" continueOnError="false" enabled="true" name="policy-name">
    <DisplayName>Policy Name</DisplayName>
    <CacheKey>
        <Prefix>prefix_string</Prefix>
        <KeyFragment ref="variable_reference"/>
        <KeyFragment>fragment_string</KeyFragment>
    </CacheKey>
    <!-- Omit this element if you're using the included shared cache. -->
    <CacheResource>cache_to_use</CacheResource>
    <Scope>scope_enumeration</Scope>
    <CacheContext>
        <APIProxyName>application_that_added_the_entry</APIProxyName>
        <ProxyName>proxy_for_which_data_was_cached</ProxyName>
        <TargetName>endpoint_for_which_data_was_cached</TargetName>
    </CacheContext>
    <PurgeChildEntries>true_to_purge_all_child_entries</PurgeChildEntries>
</InvalidateCache>

<InvalidateCache> attributes

The following table describes attributes that are common to all policy parent elements:

Attribute	Description	Default	Presence
`name`	The internal name of the policy. The value of the `name` attribute can contain letters, numbers, spaces, hyphens, underscores, and periods. This value cannot exceed 255 characters. Optionally, use the `<DisplayName>` element to label the policy in the management UI proxy editor with a different, natural-language name.	N/A	Required
`continueOnError`	Set to `false` to return an error when a policy fails. This is expected behavior for most policies. Set to `true` to have flow execution continue even after a policy fails.	false	Optional
`enabled`	Set to `true` to enforce the policy. Set to `false` to turn off the policy. The policy will not be enforced even if it remains attached to a flow.	true	Optional
`async`	This attribute is deprecated.	false	Deprecated

<DisplayName> element

Use in addition to the name attribute to label the policy in the management UI proxy editor with a different, natural-language name.

<DisplayName>Policy Display Name</DisplayName>

Default

Default	N/A If you omit this element, the value of the policy's `name` attribute is used.
Presence	Optional
Type	String

N/A

If you omit this element, the value of the policy's name attribute is used.

Presence Optional

Type String

<CacheContext>/<APIProxyName> element

Specifies the name of the application that added the cache entry.

<APIProxyName>application_that_added_the_entry</APIProxyName>

Attributes

Attribute	Description	Default	Presence	Type
ref	Variable with the application name.	N/A	Optional	String

<CacheContext> element

Specifies how to construct a cache key when a Prefix element value is not specified, or to clear cache entries added by another API proxy.

<CacheContext>
  <APIProxyName ref="variable_name">application_that_added_the_entry</APIProxyName>
  <TargetName ref="variable_name">endpoint_for_which_data_was_cached</TargetName>
  <ProxyName ref="variable_name">proxy_for_which_data_was_cached</ProxyName>
</CacheContext>

Used to construct the CacheKey. Values for APIProxyName, ProxyName, and TargetName are mandatory when a CacheKey prefix (that is, a custom prefix) is not used to clear cache entries added by another API proxy.

<CacheKey> element

Configures a unique pointer to a piece of data stored in the cache.

<CacheKey>
    <Prefix>string</Prefix>
    <KeyFragment ref="variable_name" />
    <KeyFragment>literal_string</KeyFragment>
</CacheKey>

Default:	N/A
Presence:	Required
Type:	N/A

<CacheKey> constructs the name of each piece of data stored in the cache.

At runtime, <KeyFragment> values are prepended with either the <Scope> element value or <Prefix> value. For example, the following results in a cache key of UserToken__apiAccessToken__<value_of_client_id>:

<CacheKey>
    <Prefix>UserToken</Prefix>
    <KeyFragment>apiAccessToken</KeyFragment>
    <KeyFragment ref="request.queryparam.client_id" />
</CacheKey>

You use the <CacheKey> element in conjunction with <Prefix> and <Scope>. For more information, see Working with cache keys.

<CacheResource> element

Specifies the cache where messages should be stored.

Omit this element completely if this policy (and your corresponding PopulateCache and LookupCache policies) is using the included shared cache.

<CacheResource>cache_to_use</CacheResource>

Default:	N/A
Presence:	Optional
Type:	String

For more about configuring caches, see Creating and editing an environment cache.

<CacheKey>/<KeyFragment> element

Specifies a value that should be included in the cache key, creating a namespace for matching requests to cached responses.

<KeyFragment ref="variable_name"/>
<KeyFragment>literal_string</KeyFragment>

Default:	N/A
Presence:	Optional
Type:	N/A

This can be a key (a static name that you provide) or a value (a dynamic entry set by referencing a variable). All specified fragments combined (plus the prefix) are concatenated to create the cache key.

<KeyFragment>apiAccessToken</KeyFragment>
<KeyFragment ref="request.queryparam.client_id" />

You use the <KeyFragment> element in conjunction with <Prefix> and <Scope>. For more information, see Working with cache keys.

Attributes

Attribute	Description	Default	Presence	Type
ref	The variable from which to get the value. Should not be used if this element contains a literal value.	N/A	Optional	String

<CacheKey>/<Prefix> element

Specifies a value to use as a cache key prefix.

<Prefix>prefix_string</Prefix>

Default:	N/A
Presence:	Optional
Type:	String

Use this value instead of <Scope> when you want to specify your own value rather than a <Scope> -enumerated value. If defined, <Prefix> prepends the cache key value for entries written to the cache. A <Prefix> element value overrides a <Scope> element value.

You use the <Prefix> element in conjunction with <CacheKey> and <Scope>. For more information, see Working with cache keys.

<CacheContext>/<ProxyName> element

Specifies the name of the proxy for which the data was cached.

<ProxyName>proxy_for_which_data_was_cached</ProxyName>

Default:	N/A
Presence:	Optional
Type:	String

Attributes

Attribute	Description	Default	Presence	Type
ref	The variable from which to get the value. Should not be used if this element contains a literal value.	N/A	Optional	String

<PurgeChildEntries> element

Warning: There is a known issue related to this element. Setting <PurgeChildEntries> to true purges all cache values rather than only the <KeyFragment> values. See Known Issues.

true to purge cache entries that share the value set by a <KeyFragment> element configured for this policy. Values in other parts of the cache key, such as in <Prefix> elements, are not considered.

Note that the <KeyFragment> element must be specified. If it is not, setting true for <PurgeChildEntries> could result in purging all entries in the cache.

Invalidating all of the cache entries of the same key fragment value can be a useful way to purge multiple related entries at once.

<PurgeChildEntries>true_to_purge_child_entries</PurgeChildEntries>

Default:	false
Presence:	Optional
Type:	Boolean

<Scope> element

Enumeration used to construct a prefix for a cache key when a <Prefix> element is not provided in the <CacheKey> element.

<Scope>scope_enumeration</Scope>

Default:	"Exclusive"
Presence:	Optional
Type:	String

The <Scope> setting determines a cache key that is prepended according to the <Scope> value. For example, a cache key would take the following form when scope is set to Exclusive:

orgName__envName__applicationName__deployedRevisionNumber__proxy|TargetName__ [ serializedCacheKey ].

If a <Prefix> element is present in <CacheKey>, it supersedes a <Scope> element value. Valid values include the enumerations below.

You use the <Scope> element in conjunction with <CacheKey> and <Prefix>. For more information, see Working with cache keys.

Acceptable values

Scope Value	Description
`Global`	Cache key is shared across all API proxies deployed in the environment. Cache key is prepended in the form orgName __ envName __. If you define a `<CacheKey>` entry with the `<KeyFragment>` apiAccessToken and a `<Global>` scope, each entry is stored as `orgName__envName__apiAccessToken`, followed by the serialized value of the access token. For an API proxy deployed in an environment called 'test' in an organization called 'apifactory', access tokens would be stored under the following cache key: `apifactory__test__apiAccessToken`.
`Application`	API proxy name is used as the prefix. Cache key is prepended in the form orgName__envName__applicationName.
`Proxy`	ProxyEndpoint configuration is used as the prefix. Cache key is prepended in the form orgName__envName__applicationName__deployedRevisionNumber__proxyEndpointName .
`Target`	TargetEndpoint configuration is used as the prefix. Cache key prepended in the form orgName__envName__applicationName__deployedRevisionNumber__targetEndpointName .
`Exclusive`	Default. This is the most specific, and therefore presents minimal risk of namespace collisions within a given cache. Prefix is one of two forms: If the policy is attached to the `ProxyEndpoint` flow, prefix is of the form ApiProxyName_ProxyEndpointName. If the policy is attached at `TargetEndpoint`, prefix is of the form ApiProxyName_TargetName. Cache key prepended in the form orgName__envName__applicationName__deployedRevisionNumber__proxyNameITargetName For example, the full string might look like this: apifactory__test__weatherapi__16__default__apiAccessToken .

<CacheContext>/<TargetName> element

Specifies the name of the target endpoint for which the data was cached.

<TargetName>endpoint_for_which_data_was_cached</TargetName>

Default:	N/A
Presence:	Optional
Type:	String

Attributes

Attribute	Description	Default	Presence	Type
ref	The variable from which to get the value. Should not be used if this element contains a literal value.	N/A	Optional	String

Usage notes

General purpose caching with the Populate Cache policy, LookupCache policy, and InvalidateCache policy uses either a cache you configure or a shared cache that's included by default. In most cases, the underlying shared cache should meet your needs. To use this cache, simply omit the <CacheResource> element.

For more about configuring caches, see Creating and editing an environment cache. For more about the underlying data store, see Cache internals.

Error codes

This section describes the error messages and flow variables that are set when this policy triggers an error. This information is important to know if you are developing fault rules for a proxy. To learn more, see What you need to know about policy errors and Handling faults.

Error code prefix

N/A

Runtime errors

This policy does not throw any runtime errors.

Deployment errors

These errors can occur when you deploy a proxy containing this policy.

Error name	Cause	Fix
`InvalidCacheResourceReference`	This error occurs if the `<CacheResource>` element in the InvalidateCache policy is set to a name that does not exist in the environment where the API proxy is being deployed.
`CacheNotFound`	This error occurs if the specific cache mentioned in the error message has not been created on a specific Message Processor component.

Fault variables

N/A

Example error response

N/A