Private queues for loopback calls
The AP:Admin-ServerSettings form provides the Private AR Server RPC Socket and Plugin Loopback RPC Socket fields for controlling loopback calls to the .
A loopback call occurs when the plug-in initiates a call back to the while processing approval workflow. During heavy loads, this can cause a server deadlock if enough queues or threads are not available. To avoid this, use a dedicated loopback RPC queue. The valid RPC socket number ranges are:
- 390621 – 390634
- 390636 – 390669
- 390680 – 390694
To use the approval preview feature, you must set either the Private AR Server RPC Socket or the Plugin Loopback RPC Socket.
Private AR Server RPC Socket
The Private AR Server RPC Socket field creates a private queue dedicated to loopback calls only. This setting appears in the configuration file with the tag Approval-RPC-Socket.
If both the Private AR Server RPC Socket and Plugin Loopback RPC Socket values are set, uses the Private AR Server RPC Socket.
Plugin Loopback RPC Socket
The Plugin Loopback RPC Socket field creates a private queue for all loopback calls from the plug-in server, regardless of which plug-in application initiates the call. If this value is set and the Private AR Server RPC Socket field is not set, the Plug-in server uses this queue for loopback calls. In other words, shares this queue with other plug-in applications, but not with users.
This setting appears in the configuration file with the label Plugin-Loopback-RPC-Socket.
If the Plugin Loopback RPC Program Number is already defined for the , enter the same RPC number in the Plugin Loopback RPC Socket field of the Server Settings window. If this queue is not already defined for the server, it will appear in the Server Information dialog box, on the Server Ports and Queues tab, after you enter it in the Server Settings dialog box.
For more information about defining server ports and queues, see 2024-07-10_01-44-14_Setting ports and RPC numbers.
How uses RPC settings
In releases earlier than 7.5.00, RPC settings were used as follows.
used the following RPC program numbers (defined by using fields on the AP:Admin-ServerSettings form):
- Private AR Server RPC Socket – (Optional) If a value was specified, the Private-RPC-Socket and Approval-RPC-Socket entries were created in the ar.cfg (Windows) or ar.conf (UNIX) file, and a private queue dedicated to loopback calls was used, instead of using the default administration (admin) queue at 390600.
- Plugin Loopback RPC Socket – (Optional) If specified, the Plugin-Loopback-RPC-Socket entry was created (or updated) in ar.cfg (or ar.conf), and that queue was used for the Preview feature. If this value was not provided, the Preview feature did not work.
These values were supposed to be different because they were used for different functionalities.
uses the Visualizer sub-plugin to render previews (different from the Preview feature implementation). Therefore, the same RPC queue can be used for approval processing as well as preview generation.
Following this change, the RPC settings are provided by default at the time of installation or upgrade:
- When performing a fresh installation, the Private-RPC-Socket, Approval-RPC-Socket, and Plugin-Loopback-RPC-Socket entries are created and set to 390680.
- When upgrading to release 7.5.00 or later:
- If Private-RPC-Socket, Approval-RPC-Socket, and Plugin-Loopback-RPC-Socket values are already defined in the existing setup, they are not changed.
- If Approval-RPC-Socket is not defined, but other Private-RPC-Socket entries exist, the Private-RPC-Socket and Approval-RPC-Socket entries are created and set to the next available valid value.
If this value is not specified, approval processing is done through the default admin queue. If Plugin-Loopback-RPC-Socket is not defined, the corresponding entry is created and set to the same value as that of Approval-RPC-Socket.
By default, uses this socket to run the Visualizer sub-plugin.