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# JMS Topic --> Configuration --> Thresholds & Quotas

Tasks Related Topics Attributes

## Overview

This tab defines the bytes/messages threshold and quota configuration attributes for a JMS topic. After defining a JMS server, you can configure its topics. You can configure one or more topics for each JMS server.

Note: You configure destinations explicitly or by configuring a JMS template that can be used to define multiple destinations with similar attribute settings, as described in JMS Template Tasks.

## Tasks

Creating a JMS Topic

## Related Topics

"WebLogic JMS Fundamentals" in Programming WebLogic JMS

"Managing WebLogic JMS" in Programming WebLogic JMS

"Developing a WebLogic JMS Application" in Programming WebLogic JMS

## Attributes

Table 31-1

Attribute Label | Description | Value Constraints
--- | --- | ---
Bytes Maximum | The maximum bytes quota (total amount of bytes) that can be stored in this destination. The default value of -1 specifies that there is no WebLogic-imposed limit on the number of bytes that can be stored in the destination. However, excessive bytes volume can cause memory saturation, so this value should correspond to the total amount of available system memory relative to the rest of your application load. Note: Configured quotas do not apply to expired or error (redelivery limit) messages that are redirected to an error destination. Such messages are still moved into an error destination even if that destination has reached its quotas. Range of Values: >= BytesThresholdHigh This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. Note: If a JMS template is used for distributed destination members, then this setting applies only to those specific members and not the distributed destination set as a whole. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `BytesMaximum` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Bytes Threshold High | The upper threshold value that triggers events based on the number of bytes stored in this destination. If the number of bytes exceeds this threshold, the triggered events are: Log Messages - A message is logged on the server indicating a high threshold condition. Bytes Paging - If bytes paging is enabled (and a paging store has been configured), then destination-level bytes paging is started. Flow Control - If flow control is enabled, the destination becomes armed and instructs producers to begin decreasing their message flow. A value of -1 specifies that bytes paging, flow control, and threshold log messages are disabled for the destination. However, if a JMS template is specified for this destination, then -1 implies that the value will come from the template. Range of Values: <= BytesMaximum; >BytesThresholdLow This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. Note: Bytes paging cannot be dynamically disabled by resetting the value to -1. To dynamically disable paging, you could set the value to a very large number, so that paging would not be triggered. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `BytesThresholdHigh` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Bytes Threshold Low | The lower threshold value that triggers events based on the number of bytes stored in the destination. If the number of bytes falls below this threshold, the triggered events are: Log Messages - A message is logged on the server indicating that the threshold condition has cleared. Bytes Paging - If bytes paging is enabled, paging is stopped (if paging is occurring). Flow Control - If flow control is enabled, the destination becomes disarmed and instructs producers to begin increasing their message flow. A value of -1 specifies that bytes paging, flow control, and threshold log messages are disabled for the destination. However, if a JMS template is specified for this destination, then -1 implies that the value will come from the template. Range of Values: < BytesThresholdHigh This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `BytesThresholdLow` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Bytes Paging Enabled | Specifies whether bytes paging is enabled on the destination for temporarily swapping message bodies out from memory when the destination's bytes load reaches a specified threshold. default - If a JMS template is specified, then this value inherits the template's Bytes Paging value. If no JMS template is configured for the destination, then the Default value is equivalent to false. false - Bytes paging is explicitly disabled for this destination. true - If a paging store has been configured for the JMS server, and both the BytesThresholdLow and BytesThresholdHigh attribute values are greater than -1, then bytes paging is enabled for this destination. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `BytesPagingEnabled` | Default: default Valid values: default false true
Messages Maximum | The maximum message quota (total amount of messages) that can be stored in this destination. The default value of -1 specifies that there is no WebLogic-imposed limit on the number of messages that can be stored in the destination. However, excessive message volume can cause memory saturation, so this value should correspond to the total amount of available system memory relative to the rest of your application load. Note: Configured quotas do not apply to expired or error (redelivery limit) messages that are redirected to an error destination. Such messages are still moved into an error destination even if that destination has reached its quotas. Range of Values: >= MessagesThresholdHigh This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. Note: If a JMS template is used for distributed destination members, then this setting applies only to those specific members and not the distributed destination set as a whole. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `MessagesMaximum` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Messages Threshold High | The upper threshold value that triggers events based on the number of messages stored in the destination. If the number of messages exceeds this threshold, the triggered events are: Log Messages - A message is logged on the server indicating a high threshold condition. Messages Paging - If messages paging is enabled (and a paging store has been configured), then destination-level messages paging is started. Flow Control - If flow control is enabled, the destination becomes armed and instructs producers to begin decreasing their message flow. A value of -1 specifies that messages paging, flow control, and threshold log messages are disabled for the destination. However, if a JMS template is specified for this destination, then -1 implies that the value will come from the template. Range of Values: <= MessagesMaximum; >MessagesThresholdLow This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. Note: Messages paging cannot be dynamically disabled by resetting the value to -1. To dynamically disable paging, you could set the value to a very large number, so that paging would not be triggered. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `MessagesThresholdHigh` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Messages Threshold Low | The lower threshold value that triggers events based on the number of messages stored in the destination. If the number of messages falls below this threshold, the triggered events are: Log Messages - A message is logged on the server indicating that the threshold condition has cleared. Messages Paging - If messages paging is enabled, paging is stopped (if paging is occurring). Flow Control - If flow control is enabled, the destination becomes disarmed and instructs producers to begin increasing their message flow. A value of -1 specifies that messages paging, flow control, and threshold log messages are disabled for the destination. However, if a JMS template is specified for this destination, then -1 implies that the value will come from the template. Range of Values: < MessagesThresholdHigh This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `MessagesThresholdLow` | Minimum: -1 Maximum: 9223372036854775807 Default: -1 Dynamic: yes
Messages Paging Enabled | Specifies whether messages paging is enabled on the destination for temporarily swapping message bodies out from memory when the destination's message load reaches a specified threshold. default - If a JMS template is specified, then this value inherits the template's Messages Paging value. If no JMS template is configured for the destination, then the Default value is equivalent to false. false - Messages paging is explicitly disabled for this destination. true - If a paging store has been configured for the JMS server, and both the MessagesThresholdLow and MessagesThresholdHigh attribute values are greater than -1, then messages paging is enabled for this destination. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `MessagesPagingEnabled` | Default: default Valid values: default false true
Maximum Message Size | The maximum allowable size for messages to be accepted from producers on this topic. The message size includes the message body, user-defined properties, and the user-defined JMS header fields: `JMSCorrelationID` and `JMSType`. The maximum message size is checked before messages are sent to a topic. Therefore, if a message exceeds the specified allowable size, it does not count against the topic's configured quota (bytes/messages maximum) or its upper thresholds, since the message is immediately rejected. When a producer sends a message that exceeds the specified maximum message size for the topic, it will receive a JMS `ResourceAllocation` exception. The maximum message size is only enforced for the initial production of a message. Messages that are redirected to an error destination or forwarded to a member of a distributed topic are not checked for size. For instance, if a topic and its corresponding error destination are configured with a maximum message size of 128K and 64K, respectively, a message of 96K could be redirected to the error destination (even though it exceeds the 64K maximum), but a producer could not directly send the 96K message to the error destination. This attribute is dynamically configurable, but only incoming messages are impacted; stored messages are not impacted. MBean: `weblogic.management. configuration. JMSTopicMBean` Attribute: `MaximumMessageSize` | Minimum: 0 Maximum: 2147483647 Default: 2147483647 Dynamic: yes