Cache Xbase++ Reference Documentation
Cache
Current Version: 11.6.0
Chilkat.Cache
Store and retrieve cached items by unique key, without the application
needing to manage the underlying cache filenames directly.
Cache strings, byte data, files, or Chilkat buffer objects depending on
the data form used by the application.
Associate cached items with expiration times, update expiration metadata,
and check whether cached content is still usable.
Store and retrieve ETag values for workflows that need HTTP-style cache
validation or conditional re-fetch logic.
Choose the cache root directory and use an optional multi-level directory
structure to avoid too many files in a single folder.
Delete a single cached item, remove expired items, remove older items, or
clear the entire cache when needed.
For an extended overview, see
Cache Class Overview.
Store, retrieve, expire, and clean up cached text or binary data on disk.
Chilkat.Cache is a disk-based cache class for storing and
retrieving text or binary items by unique key. It provides configurable cache
roots, optional multi-level directory layout, expiration metadata, ETag
metadata, cache lookup, fetch-status properties, expiration updates, and
cleanup methods for deleting individual items, expired items, older items, or
the entire cache.
Key-based storage
Text and binary data
Expiration control
ETag metadata
Configurable layout
Cleanup operations
Object Creation
LOCAL oCache
oCache := CreateObject("Chilkat.Cache")
// ... use oCache ...
oCache:destroy()Xbase++ uses the Chilkat ActiveX through the automation object returned by CreateObject(); properties and methods are accessed with the send operator (oHttp:ConnectTimeout := 30, oHttp:Download(cUrl, cPath)), and :destroy() releases the object. Register the Chilkat ActiveX matching the bitness of your Xbase++ application. To bind to a specific major version of Chilkat, append the major version number to the ProgID, such as CreateObject("Chilkat.Cache.11") for Chilkat v11.*.*.
Boolean properties, arguments and return values are integers in the ActiveX: pass 1 or 0, and test a method's success with == 1. A method that fails to return an object returns NIL. Objects returned by methods (such as an HttpResponse or JsonObject) are automation objects too and should likewise be released with :destroy(). Methods and properties that pass or return raw byte arrays are not shown on this page; use the BinData-based alternatives (methods ending in Bd) or the base64 / hex string-encoded variants instead.
Properties
DebugLogFilePath
If set to a file path, this property logs the LastErrorText of each Chilkat method or property call to the specified file. This logging helps identify the context and history of Chilkat calls leading up to any crash or hang, aiding in debugging.
Enabling the VerboseLogging property provides more detailed information. This property is mainly used for debugging rare instances where a Chilkat method call causes a hang or crash, which should generally not happen.
Possible causes of hangs include:
- A timeout property set to 0, indicating an infinite timeout.
- A hang occurring within an event callback in the application code.
- An internal bug in the Chilkat code causing the hang.
LastErrorHtml
Provides HTML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastErrorText
Provides plain text information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
LastErrorXml
Provides XML-formatted information about the last called method or property. If a method call fails or behaves unexpectedly, check this property for details. Note that information is available regardless of the method call's success.
topLastEtagFetched
Returns the ETag metadata associated with the most recently fetched cache item. An empty string means that the fetched item has no stored ETag.
FetchBd, FetchSb, or FetchText.If-None-Match.LastExpirationFetchedStr
Returns the expiration date and time stored for the most recently fetched cache item, formatted as an RFC 822-style Internet date. An empty string represents an item with no expiration date.
LastHitExpired after the fetch to determine whether the returned entry is stale.LastHitExpired
Returns 1 when the expiration time of the most recently fetched item is earlier than the current system date and time; otherwise returns 0.
DeleteAllExpired or DeleteFromCache.LastKeyFetched
Returns the application-defined key associated with the most recently fetched cache item.
LastMethodSuccess
Indicates the success or failure of the most recent method call: 1 means success, 0 means failure. This property remains unchanged by property setters or getters. This method is present to address challenges in checking for null or Nothing returns in certain programming languages. Note: This property does not apply to methods that return integer values or to boolean-returning methods where the boolean does not indicate success or failure.
LastStringResult
In SQL Server stored procedures, this property holds the string return value of the most recent method call that returns a string. It is accessible only when Chilkat.Global.KeepStringResult is set to TRUE. SQL Server has limitations on string lengths returned from methods and properties, but temp tables can be used to access large strings.
LastStringResultLen
The length, in characters, of the string contained in the LastStringResult property.
topLevel
Gets or sets the number of directory levels used beneath each cache root. Valid values are 0, 1, and 2.
| Value | Directory layout |
|---|---|
0 | All cache files are stored directly in the cache root. |
1 | Files are distributed among 256 first-level directories named 0 through 255. |
2 | Files are distributed through two levels of 256 directories, allowing as many as 65,536 leaf directories per root. |
NumRoots
Returns the number of cache-root directories that have been registered by calling AddRoot.
VerboseLogging
If set to 1, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is 0. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.
Version
Methods
AddRoot
Adds path as a root directory for the disk cache. Call this method once for each root that should participate in the cache.
For example, a cache distributed across D:\cacheRoot, E:\cacheRoot, and F:\cacheRoot is configured by calling this method three times.
Level setting before accessing a cache created by an earlier process or application run.DeleteAll
Deletes every cache item from all configured roots and returns the number of cache files removed. Multi-level subdirectories are retained.
DeleteAllExpired
Deletes all cache items whose stored expiration time is earlier than the current system time and returns the number of files removed.
DeleteFromCache
Deletes the cache item identified by key.
| Return value | Meaning |
|---|---|
1 | The item was deleted, or no item existed for the key. |
0 | The item exists but could not be deleted, for example because of a filesystem permission or sharing error. |
Returns 1 for success, 0 for failure.
topDeleteOlderDt
Deletes cache items older than the cutoff date and time supplied in dateTime.
Returns the number of cache files deleted, or -1 if an error occurs.
DeleteAllExpired when the decision should be based specifically on each item's expiration metadata.DeleteOlderStr
Deletes cache items older than the cutoff date and time supplied in dateTimeStr as an RFC 822-style Internet date string.
Returns the number of cache files deleted, or -1 if an error occurs.
Mon, 03 Aug 2026 12:00:00 GMT. Use DeleteOlderDt when the cutoff is already available as a CkDateTime.FetchBd
Retrieves the binary item identified by key and loads its bytes into the BinData object supplied in bd.
The key is application-defined, may contain any characters, and must uniquely identify the intended item.
1. A failed lookup or filesystem error returns 0.LastHitExpired immediately afterward when stale data must not be used.Returns 1 for success, 0 for failure.
topFetchSb
Retrieves the text item identified by key and loads its content into the StringBuilder supplied in sb.
The key is application-defined, may contain any characters, and must uniquely identify the intended item.
1. A failed lookup or filesystem error returns 0.LastHitExpired immediately afterward when stale data must not be used.Returns 1 for success, 0 for failure.
topFetchText
Retrieves the text item identified by key and returns its string content.
The key is application-defined, may contain any characters, and must uniquely identify the intended item.
LastHitExpired immediately afterward when the application requires only fresh data.Returns NIL on failure
GetEtag
Returns the ETag metadata stored with the cache item identified by key.
Returns NIL on failure
GetExpirationStr
Returns the expiration date and time stored for the item identified by url, formatted as an RFC 822-style Internet date string.
url url for historical reasons. It is the cache key and does not need to be a URL.Returns NIL on failure
GetFilename
Returns the absolute filesystem path of the cache file associated with key.
Cache API rather than modifying cache files directly.Returns NIL on failure
GetRoot
Returns the directory path of the cache root at zero-based index. Valid indexes range from 0 through NumRoots - 1.
Returns NIL on failure
IsCached
Returns 1 if an item exists for key, or 0 if the key is not present.
LastHitExpired, or read its expiration metadata, when freshness matters.SaveBd
Stores the contents of bd as binary cache data under key. If the key already exists, its data and metadata are replaced.
| Argument | Purpose |
|---|---|
key | The unique application-defined cache key. |
expiration | Expiration as an RFC 822-style Internet date string. Pass an empty string for no expiration. |
etag | Optional ETag or application metadata. Pass an empty string when unused. |
bd | The BinData containing the bytes to save. |
Returns 1 for success, 0 for failure.
topSaveTextDt
Stores itemTextData as a text cache item under key, with the expiration date and time supplied in expireDateTime. If the key already exists, its data and metadata are replaced.
eTag is optional ETag or application metadata and may be an empty string. The key may contain any characters and may be any length, but it must uniquely identify the item.
LastHitExpired to detect staleness and a deletion method to remove it.Returns 1 for success, 0 for failure.
topSaveTextNoExpire
Stores itemTextData as a non-expiring text cache item under key. If the key already exists, its data and metadata are replaced.
eTag is optional ETag or application metadata and may be an empty string.
Returns 1 for success, 0 for failure.
SaveTextStr
Stores itemTextData as a text cache item under key, with expireDateTime providing the expiration time as an RFC 822-style Internet date string. If the key already exists, its data and metadata are replaced.
eTag is optional ETag or application metadata and may be empty.
SaveTextDt when the expiration is available as a CkDateTime, or SaveTextNoExpire for an entry without expiration.Returns 1 for success, 0 for failure.
topUpdateExpirationDt
Replaces the expiration date and time of the cache item identified by key with the CkDateTime value supplied in expireDateTime. The cached data and ETag are unchanged.
Returns 1 for success, 0 for failure.
topUpdateExpirationStr
Replaces the expiration date and time of the cache item identified by key with the RFC 822-style Internet date string supplied in expireDateTime. The cached data and ETag are unchanged.
key url; it is the cache key and does not need to be a URL. Use UpdateExpirationDt for a CkDateTime value.Returns 1 for success, 0 for failure.
topDeprecated
GetExpirationDt
GetExpirationStr and load the returned value into a CkDateTime when an object representation is required.Returns the expiration date and time for the item identified by key as a newly returned CkDateTime object.
Returns NIL on failure