1.6 High Availability and the Map Visualization Component (WebLogic Server Only)
Users can benefit from the high availability features of Oracle WebLogic Server.
Note:
This section is intended for advanced users who want to take full advantage of high availability features with the map visualization component. You must have a strong understanding of high availability features, which are described in Oracle Fusion Middleware High Availability Guide.
Parent topic: Introduction to the Map Visualization Component 23.2
1.6.1 Deploying the Map Visualization Component on a Middle-Tier Cluster
The map visualization component can be deployed to a WebLogic Server cluster. You must take care, however, about how the generated image files on each host are named and referenced through URLs by client applications.
Consider the following sample scenario. When a map request is sent to the front web server, it reaches the map visualization component server running on host A. map visualization component on host A then sends back the URL for the generated map image, and the client then sends a second request to fetch the actual image. This second request might be received by WebLogic Server running on host B, which has no such image (or which will send back an incorrect image with the same name).
There is no single best solution for this problem in all environments. One option is to have the hosts share common networked storage, so that the map images are deposited in the same virtual (networked) file system by different map visualization component servers running on different hosts. You must configure the map file storage information (see Specifying Map File Storage and Life Cycle Information) for each map visualization component instance so that the images are deposited in different subdirectories or so that they have different file prefixes. Otherwise, the image files generated by the multiple map visualization component servers might overwrite each other on the disk. By properly configuring the map file storage information, you ensure that each URL sent back to the client uniquely identifies the correct map on the network drive.
If you cannot use networked drives, consider using a load balancer. You may first need to configure the map file storage information for each map visualization component instance (as explained in the preceding paragraph), so that each map visualization component instance names its generated images using an appropriate scheme to ensure uniqueness. You can then specify rules in the load balancer to have it redirect image requests to a certain host if the URL matches a certain pattern, such as containing a specified map image file prefix.