how does MID server use outbound actions for Servicenow Discovery execute now?

[aodwodud]

i am confused as to how the execute now in Discovery works. can anyone explain how that action is not an inbound access to the MID server?  Thank you

[Runjay Patel]

Hi @aodwodud ,

Once you client on UI Action "Execute Now" then it will trigger the discovery process. The 1st step it will take to check the MID Server, if it found active then it will trigger sazzam probes. ServiceNow generates outbound messages for the Shazzam probe and other probes to be executed by the MID Server and stored in ecc queue.

MID Server continuously polls the ECC Queue for output messages that need processing.

Now mid server take the input and execute the command and collect the information for target device and return the xml as a response back to servicenow. Now ServiceNow process the input xml and based on open port it will trigger the next probes/pattern.

check more here in detailed: https://servicenowwithrunjay.com/servicenow-discovery-fundamentals/ 

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Runjay Patel - ServiceNow Solution Architect
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[aodwodud]

hello @Runjay Patel  thank you for your response.

I understand the process up to where the instructions are stored into the ecc queue and the MID server polls the queue at an interval of 40 seconds by default.

what i don't understand is if the mid server only has outbound actions, how does servicenow tell the mid server to poll the ecc queue when i click the UI action execute now?

[Runjay Patel]

Hi @aodwodud ,

ServiceNow wont tell MID server, Mid server itself MID Server continuously polls the ECC Queue for output messages that need processing.

-------------------------------------------------------------------------

If you found my response helpful, please consider selecting "Accept as Solution" and marking it as "Helpful." This not only supports me but also benefits the community.

Regards
Runjay Patel - ServiceNow Solution Architect
YouTube: https://www.youtube.com/@RunjayP
LinkedIn: https://www.linkedin.com/in/runjay

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[aodwodud]

MID Server and Asynchronous Message Bus (AMB)

MID Servers are designed to subscribe to messages published by the Asynchronous Message Bus (AMB) within the ServiceNow instance. This mechanism allows MID Servers to receive notifications indicating that there are pending tasks in the ECC (External Communication Channel) queue that they need to process. These notifications signal the MID Server to take subsequent actions based on tasks assigned from the ServiceNow instance.

Nature of Notifications and Actions

While it may seem that receiving notifications from the AMB could be considered an inbound action, the events triggered by the AMB do not classify as inbound calls in the traditional sense. They do not originate from external systems directly communicating with the MID Server. Instead, these notifications are part of the internal ServiceNow operational flow and are aimed at notifying the MID Server of tasks it needs to perform.

Outbound Actions Clarified

MID Servers are explicitly designed to perform outbound actions, which means they initiate communication with external systems to retrieve data or to execute commands. While these notifications inform the MID Server of tasks, the actual data exchange and commands are sent out from the MID Server to an external resource, making all operations initiated by the MID Server outbound. This design choice is primarily for security and control of communications with the ServiceNow instance.

Summary of Inbound vs. Outbound Classification

​In summary, notifications received by the MID Server, although they indicate tasks pending for execution, do not categorize as inbound actions.​ Instead, they are part of the operational framework of ServiceNow, facilitating the MID Server’s ability to perform tasks in an outbound manner. Therefore, it is essential to distinguish between notifications (internal processes) and communications initiated by the MID Server (outbound actions) to understand the architecture involved in these operations more clearly.

Conclusion

Thus, while MID Servers do receive notifications regarding pending tasks, these interactions remain within the scope of outbound actions, ensuring that the MID Server acts securely and consistently within its designed role in the ServiceNow ecosystem. The inbound perception does not apply here as the core functionality remains oriented towards outbound task execution.