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The News Checker component allows you to check whether the specified resource is relatively up-to-date to the previously downloaded and to download a new one if it is necessary. The process of checking, downloading and displaying can be customized by defining the events sequence. By default, News Checker checks the following resource parameters (which are expected to be received in the HTTP resource header): resource size and resource date.
You may use this component for implementing online update of your software, online data replication and many other purposes.
Please see the How to implement automatic asynchronous data exchange in the company article to learn more about using this component.
Please see the Demos code (MultiDownLoader) and also the indexed Help documentation provided with the Clever Internet Suite installation for more details about using this component.
The most common members of the News Checker component can be seen below:
 Name |
 Description |
 DataStream |
Defines the data stream to which the downloaded resource is saved. |
| Errors |
Contains a list of errors for the internet control. |
| IsNewsExists |
Specifies whether any of the updated news resource can be downloaded. |
| LocalFile |
Specifies the file name, to which the downloaded resource is saved. |
| Password |
Specifies the password that allows a control to log on to the server. |
| Priority |
Determines the resource processing scheduling priority relative to other processes. |
HttpProxySettings,
FtpProxySettings |
Specifies the name of the proxy server(s) to use when access via proxy is specified. |
| URL |
Specifies the Uniform Resource Locator (URL), from which the resource should be downloaded. |
| UserName |
Specifies the user name that allows a control to log on to the server. |
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| Name |
Description |
| Start |
Starts the news checking process. |
| Stop |
Stops the news downloading. |
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| Name |
Description |
| OnNewsExists |
Occurs immediately when a resource is really up-to-date and is successfully downloaded to the local computer. |
| OnIsNews |
Occurs on downloading the news resource. Write this event handler to redefine the algorithm which is used to determine whether the downloaded resource is up-to-date. |
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