Some of the content described in this article is available in meshIQ Manage versions 12.1 and later.
For a quick overview of what's new or changed, visit the meshIQ Highlights page for a version-by-version breakdown.  

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Version 12.x and Later
Version 11.3 and Earlier

Version 12.x and Later

An MQTT Retain Cache in a Solace Message VPN stores the most recent retained messages published to MQTT topics.
When a client subscribes to a topic with retained messages, the broker automatically delivers the last retained message from the cache, ensuring new subscribers always receive the latest state update.
This feature helps maintain message continuity in IoT and telemetry applications where device states or configuration updates need to persist.

Browse Existing MQTT Retain Caches

1. In the Message VPNs widget, select the Message VPN you want to view.

2. From the Selected menu, navigate to:
   Browse Objects > Browse Mqtt Retain Caches.
   

3. The Mqtt Retain Caches tab opens in the Console, displaying the retained message details configured for the selected Message VPN. 
   If a MQTT retain cache has not been added to the Message VPN, see the steps below to create one.
   

Add a New MQTT Retain Cache

To create an MQTT Retain Cache:

1. In the Mqtt Retain Caches tab, click the Add Link button.

2. The Solace Msg Vpn Mqtt Retain Cache dialog opens.
   

3. Enter the Mqtt Retain Cache Name (mandatory), set Enabled to True or False, and fill in the remaining necessary details as required.

4. Click Ok to create the MQTT Retain Cache immediately, or Schedule to create it at a later time.
   (See Scheduling Jobs for more information.)

Only one MQTT Retain Cache can be created for each Message VPN.

Once created, the new MQTT Retain Cache appears in the MQTT Retain Caches tab with its configuration details and operational status in console.
It starts retaining published MQTT messages based on the configured cache parameters and memory limits.

Enable or Disable MQTT Retain Cache

1. While browsing MQTT retain caches in the Console, select the retain cache and click Properties from the Selected menu.

2. The MQTT Retain Cache Properties dialog opens.

3. Set Enabled to True to enable the retain cache, or False to disable it.

Delete Retained Messages

1. While browsing the MQTT Retain Cache in the Console, select the MQTT Retain Cache and click Delete from the Selected menu.

2. The Confirm Delete Action dialog opens.
   

3. Click Yes to delete immediately, or Schedule to delete later.
   (See Scheduling Jobs for more information.)

Version 11.3 and Earlier

An MQTT Retain Cache in a Solace Message VPN stores the most recent retained messages published to MQTT topics.
When a client subscribes to a topic with retained messages, the broker automatically delivers the last retained message from the cache, ensuring new subscribers always receive the latest state update.
This feature helps maintain message continuity in IoT and telemetry applications where device states or configuration updates need to persist.

Browse Existing MQTT Retain Caches

1. In the Message VPNs viewlet, select the Message VPN you want to view.

2. From the Selected menu, navigate to:
   Browse Objects > Browse MQTT Retain Caches.
   

3. The MQTT Retain Caches tab opens in the console, displaying the retained message details configured for the selected Message VPN. 
   If a MQTT retain cache has not been added to the Message VPN, see the steps below to create one.
   

Add a New MQTT Retain Cache

To create an MQTT Retain Cache:

1. In the MQTT Retain Caches tab, click the Add Link button.

2. The Solace Msg Vpn MQTT Retain Cache dialog opens.
   

3. Enter the MQTT Retain Cache Name (mandatory), set Enabled to True or False, and fill in the remaining necessary details as required.

4. Click Ok to create the MQTT Retain Cache immediately, or Schedule to create it at a later time.
   (See Scheduling Jobs for more information.)

Only one MQTT Retain Cache can be created for each Message VPN.

Once created, the new MQTT Retain Cache appears in the MQTT Retain Caches tab with its configuration details and operational status in console.
It starts retaining published MQTT messages based on the configured cache parameters and memory limits.

Enable or Disable MQTT Retain Cache

1. While browsing MQTT retain caches in the console, select the retain cache and click Properties from the Selected menu.

2. The MQTT Retain Cache Properties dialog opens.

3. Set Enabled to True to enable the retain cache, or False to disable it.

Delete Retained Messages

1. While browsing the MQTT Retain Cache in the console, select the MQTT Retain Cache and click Delete from the Selected menu.

2. The Confirm Delete Action dialog opens.
   

3. Click Yes to delete immediately, or Schedule to delete later.
   (See Scheduling Jobs for more information.)