Kbase P128359: How to make a WebClient application resilient to downtime on the web server?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
16/10/2008 |
|
Status: Unverified
GOAL:
Is there any failover alternative available in WebClient ?
GOAL:
Is it possible to modify the URL registry key under HKLM/<ApplicationName>/ProwcappLocator to obtain a failover behaviour?
GOAL:
How to make a WebClient application resilient to downtime on the web server?
GOAL:
How is it possible to allow WebClient applications to start even when the web server is currently under maintenance?
FACT(s) (Environment):
Progress 9.x
OpenEdge 10.x
Windows
FIX:
Each time a WebClient application starts, prowcini connects to the web server to check the availability of a new version. If the web server is temporarily unavailable, this causes prowcini to fail and the application does not start, even if its AppServer or AIA is up and running.
In order to make the WebClient application resilient, several approaches are possible:
- set up an intermediary HTTP proxy with a file cache between the web server and the WebClient application. The proxy should then be used to install the application and as application URL in the Application Packager. This way when the web server is down, the HTTP proxy serves as interim.
- set up multiple web servers able to serve the same files, using the same virtual host name. Then configure the DNS server to serve the different IP addresses using a round-robin algorithm for the virtual host name, using a very short lifetime (TTL, time to live). When a web server is down, it is then sufficient to change the DNS to stop serving the corresponding IP address.
Details about how to perform this configuration is outside the scope of Progress Technical Support. Contact a systems and network administrator.