Deploying Application Proxies
To access a COM+ server application remotely from another (client) computer, the client computer must have a subset of the attributes of the server application installed, including proxy/stub DLLs and type libraries for DCOM/QC interface remoting. This subset is called an application proxy.
Through the Component Services administrative tool, you can easily export a COM+ server application as an application proxy. For COM+ to generate an application proxy, it is important that all components in the server application were installed and not imported. (For more information on this distinction, see Importing Components.) This ensures that the application includes all the necessary registration information.
Note It is recommended that you separate the interface definitions from the class implementations. Otherwise, the set of DLLs or type libraries included in the COM+ application proxy will include actual server code.
Application proxies generated by COM+ are Windows Installer installation packages. After installation, the application proxies appear in the client computer's Add/Remove Programs control panel (unless the .msi file is modified using a Windows Installer authoring tool).
When generating an application proxy, COM+ automatically provides the following information, required for the application proxy to remotely access a COM+ server application:
- Class identity information (CLSIDs and ProgIDs). An application proxy supports up to two ProgIDs.
- Application identity and relation of classes to applications (AppID).
- Location information per application (Remote Server Name).
- Marshaling information for all the interfaces exposed by the application (for example, type libraries and proxy/stubs).
- MSMQ queue names and identifiers (if the queued components service is enabled for the application).
- Class, interface, and method attributes, excluding role information.
- Application attributes.
Unlike COM+ server applications, application proxies can be installed on any operating system that supports DCOM (and Windows Installer). On computers that aren't running COM+, only the subset of information required for DCOM remoting is installed. This information is installed into the Windows registry (using the HKEY_CLASSES_ROOT, APPID/CLSID keys).
Note When installing an application proxy (.msi file) on computers that aren't running COM+, it is necessary to have Windows Installer running on those computers. It is recommended that developers ship the Windows Installer redistributable file (instmsi.exe) along with their application's .msi file. This will ensure that system administrators have Windows Installer available when deploying application proxies on clients that are not running COM+.
On computers running COM+, the application proxy information is installed into the COM+ catalog and is visible in the Component Services administrative tool.
- Creating Installation Packages for COM+ Applications
- The COM+ Catalog
- The COMREPL Replication Utility