How the Application Dependencies feature in SAM works
Depending on how the Application Dependencies feature is configured for your environment, SAM can use two types of polling to collect data:
- Application Dependency polling discovers and monitors the following types of connections:
- Application to application, in a typical client/server process monitored by SAM
- Application to server, with a server process not currently monitored by SAM
- Server to application, with a client application process not monitored by SAM
- Connection Quality polling tracks TCP communication traveling from servers that host applications to target servers. This synthetic polling collects latency and packet loss statistics for connections without intercepting network traffic, also known as "packet sniffing."
To monitor application dependencies, SAM uses Orion agents to flag nodes, which represent physical or virtual servers. An agent must exist on at least one of the two nodes for which you want to display dependencies.
You can deploy agents by adding at least one application monitor to each node you want to monitor, as described in Configure Application Dependencies settings in SAM. If a node does not host an agent, the Application Connections widget displays sample data on the Node Details page, as shown here.
To support the Application Dependencies feature, SAM deploys agent plug-ins to nodes to monitor connections and network communications. Plug-ins gather data from any Additional Polling Engines to send to the Main Polling Engine.
Tip: Enable "Allow automatic agent updates" on the Manage Agents > Edit Agent Settings page so you don't have to update plug-ins manually.
For Application Dependency polling:
- SAM deploys agent plug-ins to nodes if Application Dependency polling detects application-to-application or application-to-node connections.
- Agent plug-ins collect data about dependencies between applications (application-to-application connections) and/or nodes (application-to-node connections). It is available in Linux x64, Linux x86, and Windows versions.
To avoid performance issues, SAM does not deploy Application Dependencies plug-ins to the Main Polling Engine, which is usually the Orion server.
For Connection Quality polling, if enabled:
- SAM deploys additional agent plug-ins to collect TCP latency and packet loss metrics.
- For Windows nodes connected to clients that host applications and application processes, TCP agent plug-ins include an Npcap driver to support Nping.
SAM relies on server-initiated communications to detect "from” or to" nodes, also called “passive agents” or “agentless" nodes. Only one node in a pair requires an agent plug-in. However, note that data gathered by polling depends on communication settings for both nodes, as described here:
- If target and client nodes both host agent plug-ins, SAM collects data via Application Dependency and Connection Quality polling for both nodes.
- If only the target node has an agent plug-in, SAM collects IP address and port data for the client node but not application details, process names, or connection statistics.
- If only the client node has an agent plug-in, SAM collects IP address and port data for the server node. If Connection Quality polling is enabled and SAM deployed a TCP agent plug-in to the connection source node, polling can capture latency and packet loss statistics.
Use the Manage Agents page to check the status of agent plug-ins.