Best Practices

Avoid repeating the same DCI lookup on every poll cycle — resolve the DCI once and reuse the result. Use the DCI access methods on the node object (findDCIById(), findDCIByName(), findDCIByDescription(), findDCIByTag(), findDCIByTagPattern(), findAllDCIs()); the global functions they replace (FindDCIByDescription(), GetDCIValue(), etc.) are deprecated since version 7.0 and produce compilation warnings.

// Good: look up the DCI object once, then read its value
dci = $node.findDCIByDescription("CPU Usage");
if (dci != null)
{
    value = dci.currentValue;
}

Transformation scripts run every time a DCI value is collected (often every 60 seconds per DCI). Avoid GetAllNodes() or other functions that iterate large datasets in this context.

The trace() function writes to the server log with the nxsl.trace tag. Level 0 is always written (as an informational message); messages with level greater than 0 are emitted only when the debug level for the nxsl.trace tag is raised to at least that level. In high-frequency contexts (transformations, status polls), excessive level-0 tracing creates I/O overhead — use higher levels for debug output that should normally stay silent.

Functions like FindObject(), GetDCIValue(), and createSNMPTransport() can return null. Always verify the result before using it.

node = FindObject("Core-Router-01");
if (node == null)
{
    trace(1, "Object not found");
    return null;
}

The ?. operator provides concise null handling for chained property access.

// Instead of checking each step:
name = $node?.name;  // Returns null if $node is null

When scripts execute actions that affect infrastructure, remember that NetXMS can enforce trusted object validation. See Script Security for details.

A transformation script should do one thing: transform a value. If you need complex logic, move it to a separate script in the Script Library and call it from the transformation.

Especially in scripts stored in the Script Library that others may maintain.

When storing scripts in the Script Library, note which script context they are designed for (transformation, EPP filter, auto-bind, etc.).