autoupgrader CacheOptions property
Return to Introduction  Previous page  Next page
Applies to
auAutoUpgrader and auHTTP components.  

Declaration
type  
  TauCacheOption   = (coAlwaysReload, coReloadIfNoExpireInformation,  
                      coReloadUpdatedObjects, coPragmaNoCache,  
                      coNoCacheWrite, coCreateTempFilesIfCantCache,  
                      coUseCacheIfNetFail);  
  TauCacheOptions = set of TauCacheOption;  
 
property CacheOptions: TauCacheOptions;  

Description
The CacheOptions property controls the cache options for the AutoUpgrader component and determines how the component should use standard Internet Explorer's cache.  
 
The cache control has following options:  
ValueMeaning  
coAlwaysReloadForces a download of the requested file, object, or directory listing from the origin server, not from the cache.;  
coReloadIfNoExpireInformationForces a reload if there was no Expires time and no LastModified time returned from the server when determining whether to reload the item from the network.;  
coReloadUpdatedObjectsReloads HTTP resources if the resource has been modified since the last time it was downloaded;  
coPragmaNoCacheForces the request to be resolved by the origin server, even if a cached copy exists on the proxy;  
coNoCacheWriteDoes not add the downloaded entity to the cache;  
coCreateTempFilesIfCantCacheCauses a temporary file to be created if the file cannot be cached;  
coUseCacheIfNetFailReturns the resource from the cache if the network request for the resource fails due if connection with the server has been reset, or the attempt to connect to the server failed.  

Notes
iiinfo The AutoUpgrader autmatically set coPragmaNoCache flag to True when reading the Info-file. Other options valid for both stages: checking the Info-file for intermation and when it download files.  
 
tip The cache of Internet Explorer is very smart, so it will re-download the files even if they has been updated on the server, even if it already exists in the cache.  
Using the cache is recommended! It will save you a lots of bandwidth if connection unexpectedly lost on user PC, or user break the downloading on the half way, to upgrade the application a moment later.  

See also
InternetOptions property;  
CheckUpdate and Abort methods.