OIC - About Connectivity Agents | connectivity agents architecture | Connectivity Agents in High Availability

About Connectivity agents:

• The on-premises connectivity agent enables you to create integrations and exchange messages between on-premises applications  and Oracle Integration.
• Message payloads of up to 10 MB are supported through the use of compression.
• The on-premises connectivity agent provides multi-threading support, which allows for multiple executors to perform downstream message processing.
• The whole execution of request - response should be completed within 240 seconds , otherwise the processing will fail.

This type of integration enables you to:

• Access SOAP/REST endpoints exposed by applications such as Oracle E-Business Suite, Siebel and JD Edwards and any on-premises home grown SOAP/REST APIs.
• Access non-HTTP based endpoinds such as databses, JMS , AQ, local file systems, SAP and others.

Types of agents:

Execution agent / SaaS agent: 

• This agent is installed and runs in Oracle Integration and supports communication with on-premises applications. 
• There is one SaaS agent per Oracle Integration environment.

Connectivity agent / on-premises agent:

• This agent is installed and runs in an on-premises environment on the same network as internal systems such as Oracle EBS, Oracle Siebel, Oracle Database and others.
• There can be multiple host systems, each running one more agents, in a cloud/on premise topology. The On-premises agent does not permit any explicit inbound connections. All connections are established from the on-premises environment to Oracle Integration.

Agent Group:

• An agent group is a unique identifier which comprises multiple connectivity agents.
• You must create a agent group in OIC before you can run the connectivity agent installer.
• For a single oracle integration instance, you can create up to 5 agent groups. If the limit exceeds, you will get error like "Max limit reached. Maximum 5 Connectivity agents can be added."

Connectivity Agent Architecture:

All communication is initiated by the agent to the integration cloud and not vice versa.
The agent posts a regular heartbeat to ICS to signal that it is alive and this reflects as a green agent health status in ICS monitoring console. The agent continuously polls ICS for any design time and runtime work that needs to be processed On-premise.

• The design time work includes Test Connection, Activation, Deactivation requests.
• This runtime work comprises of processing invoke messages that need to be sent to On-premises systems like database, EBS or provate SOAP or REST endpoints. The runtime also includes trigger messages that originate On-Promise (for adpaters configured as trigger in flows).This agent makes https REST calls to integration Cloud for all its communication.

For  more details click here managing-agent-groups-and-connectivity-agent

Use the Connectivity Agent in High Availability Environments:

• We can use the connectivity agent in high availability environments with oracle integration. We need to install the connectivity agent twice on different hosts. 
• The connectivity agents can scale horizontally, thereby providing all the benefits of running multiple agents for an agent group. This results in increased performance and extends failover benefits.
• Ensure that both agent instances can access the same endpoints. For example, agent 1 on host 1 and agent 2 on host 2 must both be able to access the same endpoint (for example, a Siebel system).

Considerations:

• You cannot have more than two agent instances per agent group. Attempting to include a third agent instance in the same group during installation results in an error.

• The File Adapter and FTP Adapter are not supported in high availability environments. When using the File Adapter or FTP Adapter and some groups have multiple instances, use a dedicated agent group (with one agent only).

Oracle References:

https://docs.oracle.com/en/cloud/paas/integration-cloud/integrations-user/use-agent-high-availability-environments.html