Introduction to the Microsoft Information Delivery API

  • Article

Obsolete. The Microsoft Information Delivery API enables you to create subscriptions and add channels that can be used to deliver content to a user's computer. This section is an overview of the services provided by the Information Delivery API.

Windows Internet Explorer 7 and later. The technology described in this overview is obsolete and should not be used.

The following topics are covered in this article.

  • Introduction
  • About the Channel Manager
  • About the Subscription Manager
  • Checking Updates
  • Refreshing the Channel Pane

Introduction

The Information Delivery API provides a Channel Manager and Subscription Manager to manage channels and subscriptions.

The Channel Manager is used to add and delete any Microsoft Active Channel and channel categories from the channel pane. The Channel Manager can also retrieve an enumerator that can be used to enumerate all the current Active Channels. The Channel Manager does not create a subscription to an Active Channel. To create a subscription to an Active Channel, the client application must access the Subscription Manager.

The Subscription Manager provides the ability to create and delete subscriptions to Web sites and Active Channels. The Subscription Manager also provides the ability to start an update for a specified subscription or all subscriptions.

To use the Channel Manager, the Chanmgr.h header file must be included. Also, the Subsmgr.h header file must be included for any C/C++ programs that use the Subscription Manager.

This documentation assumes that you have an understanding of OLE and Component Object Model (COM) programming and a basic understanding of Microsoft Active Desktop and other features of Microsoft Internet Explorer 4.0

About the Channel Manager

The Channel Manager allows a client application to add and delete categories and Active Channels in the desktop channel bar. The Channel Manager can also provide an enumerator that will allow a client application to enumerate all the Active Channels. The Channel Manager does not create a subscription to the Active Channel. To subscribe to an Active Channel, the Subscription Manager must be used.

About the Subscription Manager

The Subscription Manager gives a client application the ability to create, update, and delete subscriptions to Web sites and channels. The Subscription Manager also provides the ability to get information about a subscription type and information on a specific subscription.

Checking Updates

Currently, the Information Delivery API does not provide a programmatic way of checking the last time a file has been updated. If the file is stored in the Internet cache or in a cache container, the Microsoft Win32 Internet (WinInet) function, GetUrlCacheEntryInfoEx, can be used to retrieve information on the cache entry. This information includes:

  • Last modified time
  • Expire time
  • Last access time
  • Last synchronization time
  • Returned headers
  • Hit rate
  • File size
  • Local file name
  • User count

For more information on the retrieving cache entry information, see Caching in the Introduction to the Microsoft Win32 Internet Functions. The article demonstrates the use of the GetUrlCacheEntryInfo function, which is almost identical to GetUrlCacheEntryInfoEx, except GetUrlCacheEntryInfo does not translate through the offline redirects.

Refreshing the Channel Pane

The Information Delivery API does not provide any programmatic way to refresh the channel pane. To refresh the channel pane, the client application needs to use the SHChangeNotify function with the full path of the channel shortcut.

The following sample demonstrates a call to SHChangeNotify to refresh the channel pane to show changes to the Awesome Computers channel.

SHChangeNotify(SHCNE_UPDATEDIR, SHCNF_PATH,
    (void*)"c:\windows\favorites\channels\awesome_computer", NULL);