BT Messagebox Host Test

The first time you configure a BizTalk server,  the following set of tables are created in the MessageBox database for a BizTalkServerApplicationHost:

  • The BizTalkApplicationQ
  • The BizTalkServerApplicationQ_Suspended
  • The BizTalkServerApplicationQ_Scheduled
  • The InstanceStateMessageReferences_BizTalkServerApplication

BizTalk uses these tables to keep references of all the messages that are “live” in the system .  That is: Messages with active subscriptions, suspended messages, and awaiting messages associated to each host.

The word references implies that the host tables are only pointers to the Spool table, but the real messages itself are saved in another set of tables ( messageparts, parts  and fragments).

This test monitors the number of message references in the host queue tables, and proactively alerts administrators to the following:

  • A sudden/consistent increase in the length of the host queues
  • Too many message references in the suspended queue

Target of the test : A BizTalk Server 2010

Agent deploying the test : An internal agent

Outputs of the test : One set of results for each host instance on the BizTalk server being monitored

Configurable parameters for the test
Parameters Description

Test period

This indicates how often should the test be executed.


The host for which this test is to be configured.


The port at which the host listens to.


If this parameter is set to Yes, then it means that, by default, all BizTalk servers being monitored by the eG system are the passive servers of a BizTalk cluster. No alerts will be generated if the servers are not running. Measures will be reported as "Not applicable" by the agent if the servers are not up.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Message references in Instance Queue

Indicates the number of message references in the instance state queue of this host instance.


The State Queue table holds the list of messages that have been processed by an instance but will be needed later. When an orchestration uses the State Queue, it is usually because the orchestration performed some operations on a message, persisted the message, and might need the message later. This is normal operation, and you should take this into account when determining correct sizing of the State Queue

Instances of Host Queue

Indicates the number of instances of the host queue for this host instance.



Messages in Host Queue

Indicates the number of messages in the host queue of this host instance.


Generally, this queue should not grow too large. The length of the queue indicates the number of messages waiting to be processed. A large number means you could have a backlog.

Suspended Messages in Host Queue

Indicates the number of suspended messages for this host instance.


When a message gets suspended it remains in the message box until resume or terminate actions occurs. So, if the suspended queue keeps growing, the performance of the BizTalk server will continue to get affected. A suspended message can be due, for example,  to parsing errors, serialization errors, failed transmissions, or the inability to find a subscription.