Subscription Monitoring

View live subscription data, delete durable subscriptions, and query subscriptions across several metrics.

You can view the following subscription metrics:

Subscriptions with Most Messages Published

This query shows the subscriptions to which the most messages are successfully published since the Eclipse Amlen server was started or the subscription was created, whichever is the most recent. This statistic increments when a message is accepted by the subscription. Use this statistic to see which subscriptions and applications are the most active. You might use this information for further investigation. For example, a figure that is higher than expected might indicate a rogue publisher.
Subscriptions with Most Messages Buffered

This query shows the subscriptions with the highest number of published messages that are waiting to be sent to the client. Subscriptions with high numbers of buffered messages can increase memory consumption. You might want to end, or delete, subscribing applications that have a high number of buffered messages if memory is limited.
Subscriptions with Highest % of Messages Buffered

This query shows the relative number of messages that are buffered, as a percentage of the total number of messages that can be buffered. If the buffer reaches 100%, then messages are rejected. You can use this statistic to understand which subscriptions are reaching full capacity. You might want to change the messaging policy to have a higher number of buffered messages to allow for subscriptions that are nearing 100%.
Subscriptions with Most Messages Rejected

This query shows the subscriptions with the most rejected messages. Rejected messages are messages that are sent by a publisher after the buffer is full. If many client IDs have messages that are rejected, then you might want to increase the size of the buffer by changing the messaging policy. This new value is applied to new subscriptions. To apply the change to existing subscriptions, you must end the subscription and then reinstate it. Stopping and restarting a subscription might result in lost messages. If these messages are critical you might want to stop the publisher, ensure that all messages are received by the subscriber, restart the subscription, and then restart the publisher. Alternatively you might want to verify that client IDs with a high number of rejected messages are active and able to receive messages. If the highest number of rejected messages is returned as 0, then this information can be used to confirm that no messages are rejected.
Subscriptions with Most Messages Expired

This query shows the subscriptions with the highest number of expired messages since the Eclipse Amlen server was started or the subscription was created, whichever is the most recent. A higher than expected figure might indicate that the value of the messaging policy parameter MaxMessageTimeToLive is too low. Alternatively, the application that is publishing or sending the messages might set too low a value for message expiry. The time that is set for message expiry is the lower of the values set in MaxMessageTimeToLive and the value set by the application. If you do not set a value for this parameter, or set it to have a value of unlimited, you might expect no messages to expire. However, if the publishing application sets a message expiry value on the messages, messages will expire in that time.
Subscriptions with Most Messages Discarded

This query shows the subscriptions with the highest number of messages that are not delivered because they were discarded when the buffer became full. This value pertains to the period since the Eclipse Amlen server was started or the subscription was created, whichever is the most recent. If a higher number than expected of messages is being discarded, consider the value that is specified on the MaxMessages parameter on the messaging policy; it might be too low.
Subscriptions that have come closest to capacity

This query shows the subscriptions that have the highest peaks of buffered messages as a percentage of the total number of messages that can be buffered. That is, the subscriptions that have come closest to reaching the Max Messages limit. If you use a REST Monitoring API, this percentage is displayed as BufferedHWMPercent.
Subscriptions with Least Messages Published

This query shows the subscriptions to which the least messages are successfully published since the Eclipse Amlen server was started or the subscription was created, whichever is the most recent. Use this statistic to see which subscriptions and applications are the least active. You might use this information for further investigation. For example, a figure that is lower than expected might indicate that there is a problem with a subscriber.
Subscriptions with Least Messages Buffered

This query shows the subscriptions with the lowest number of published messages that are waiting to be sent to the client. This statistic indicates which subscribers are the most successful at processing messages that are received.
Subscriptions with Lowest % of Messages Buffered

This query shows the relative number of messages that are buffered, as a percentage of the total number of messages that can be buffered. If the buffer reaches 100%, then messages are rejected.
Subscriptions with Least Messages Rejected

This query shows the subscriptions with the lowest number of rejected messages. If messages are rejected, you might want to undertake further investigation.
Subscriptions with Least Messages Expired

This query shows the subscriptions with the lowest number of expired messages. If subscriptions are getting full and messages are being rejected (failing to publish or put), the value of the messaging policy parameter MaxMessageTimeToLive is too high. If you amend the setting of this parameter to a lower value, more messages would expire rather than be rejected.
Subscriptions with Least Messages Discarded

This query shows the subscriptions with the lowest number of messages that are not delivered because they were discarded when the buffer became full. This value pertains to the period since the Eclipse Amlen server was started or the subscription was created, whichever is the most recent. If a lower number than expected of messages is being discarded, check whether the subscription is using the intended messaging policy. Check whether the MaxMessagesBehavior parameter in the messaging policy is to discard old messages; if this parameter is not set to discard old messages, messages will be rejected rather than discarded.
Subscriptions that have stayed furthest from capacity

This query shows the subscriptions that have the lowest peaks of buffered messages as a percentage of the total number of messages that can be buffered. That is, the subscriptions that have stayed furthest from the Max Messages limit. If you use a REST Monitoring API, this percentage is displayed as BufferedHWMPercent.