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Tech Tip: Using the Agent Outbound Message Queue

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Background: In the event that a Gateway/Connector Agent is offline or unable to connect to the Axeda Cloud Server, it uses an internal message queue to store information until the connection is restored. The message queue size is configured in the Axeda Builder project.

By default, the queue is 200KB in size. Depending on how frequently your Agent sends data or how much data your Agent is collecting and trying to send, 200KB may be too small.  If the queue is too small, the data will “overflow” the queue. The queue is kept in memory only; data is not stored to disk and will be removed in a First-In-First-Out (FIFO) manner when the queue overflows. If you see queue overflow error messages in the Agent log (either EKernel.log and xGate.log), it may be time to change the size of the outbound message queue.

The correct size setting for the Agent outbound message queue takes three variables into consideration:

  • How much information you are sending?
  • What is the maximum expected duration for loss of connection to the Internet (Cloud Server)?
  • How much memory is available for your process?

The more information the Agent is trying to send, the larger the queue size setting should be. Consider also that if your Agents are offline (disconnected) for a long period of time, they will likely accumulate lots of data, which may overflow the outbound message queue. If this is the case, you’ll need to increase the queue or risk losing data.

Recommendation: Consider how the Agent operates (offline/online data collection) and how much data may be queued. When selecting the size of the queue, it’s important to maintain a balance between protecting against data loss and not occupying too much memory. If you do determine that you need to increase the outbound message queue size based, it’s important to note that Axeda recommends a maximum size of the outbound message queue of about 2MB.

Need more information? For information about specifying Agent outbound message queue size, see the online help in Axeda® Builder (Enterprise Server Settings). For information about how the Agent delivers data to the Platform (via EEnterpriseProxy/xgEnterpriseProxy), see the Agent user’s guide for your Agent: either Axeda® Platform Axeda® Gateway User’s Guide (PDF) or Axeda® Platform Axeda® Connector User’s Guide (PDF). Axeda Support Site links: Axeda® Gateway User’s Guide, Axeda® Connector User’s Guide.


Hi Randy, thank you for the input, even though it's long ago.  🙂

Suppose we want to keep the queue size relatively small, but also to make sure that no outbound message gets lost by introducing an additional, file-based queue. => We could develop a custom component that extends IEnterpriseProxy and overrides ("wraps") all post methods.

Is this feasible?

Has it been done already?

Are there other ways to (more or less) guarantee successful data transfers?

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Last update:
‎Jul 28, 2014 10:27 AM
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