Package net.sf.saxon.query

## Interface UpdateAgent

-     public interface UpdateAgent

  An UpdateAgent is a callback class that is called to handle a document after it has been updated. Typically the UpdateAgent might take responsibility for writing the updated document back to persistent storage.

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `update​(NodeInfo node, Controller controller)` | Handle an updated document.

- - ### Method Detail

    - #### update

          void update​(NodeInfo node,
                      Controller controller)
               throws XPathException

      Handle an updated document. This method is called by `XQueryExpression.runUpdate(DynamicQueryContext, UpdateAgent)` once for each document (or more generally, for the root of each tree) that has been modified by the update query.
      Parameters:
        `node` - the root of the tree that has been updated
        `controller` - the Controller that was used for executing the query
      Throws:
        `XPathException` - if the callback code cannot handle the updated document