Package com.tailf.maapi

Class MaapiCursor

Object
com.tailf.maapi.MaapiCursor
public class MaapiCursor extends Object
Whenever we wish to iterate over a set of objects in the XML tree, we must first initialize a cursor. The cursor is subsequently used in a while loop.

For example if we have: 

 module mtest {
   namespace "http://tail-f.com/test/mtest/1.0";
   prefix mtest;

   import ietf-inet-types {
     prefix inet;
   }
   import tailf-common {
     prefix tailf;
   }

   container mtest {
     container servers {
       list server {
         key name;
         max-elements 64;
         leaf name {
           type string;
         }
         leaf ip {
           type inet:host;
           mandatory true;
         }
         leaf port {
           type inet:port-number;
           default 80;
         }
         list interface {
           key name;
           max-elements 8;
           leaf name {
             type string;
           }
           leaf mtu {
             type int64;
             default 1500;
           }
         }
       }
     }
   }
 }

We can have the following Java code which iterates over all 'server' instances. 

 MaapiCursor c;
 ConfKey x;

 c = maapi.newCursor(th, "/mtest:mtest/servers/server");

 x = maapi.getNext(c);
 while (x != null) {
     // do something
     x = maapi.getNext(c);
 }
A cursor can also be created with an XPath filter: 

 MaapiCursor c =
     maapi.newCursorWithFilter(th,
                               "starts-with(ip, \"10.\") and port > 8000",
                               "/mtest:mtest/servers/server");
See Also:

  • Method Details

    • getPrev

      public ConfEObject getPrev()

    • getPath

      public ConfPath getPath()

    • getTid

      public int getTid()

    • getId

      public int getId()

    • setPrev

      public void setPrev(ConfEObject prev)

    • setSecondaryIndex

      public void setSecondaryIndex(String idx)
      Makes it possible to use a secondary index for the getNext calls.
      Parameters:
      idx - Secondary index name

    • getSecondaryIndex

      public String getSecondaryIndex()
      Return the name of the specified secondary index (if any).

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getFilter

      public String getFilter()
      Return the XPath filter for this cursor, or null if there is none.
      Returns:
      XPath filter for this cursor

    • destroy

      public void destroy()

      Destroy the cursor on the server side.

      There is normally no need to call this method. Only call it if the use pattern below feels familiar.

      If iteration is ended before all results have been fetched the cursor will still be held on to on the server side since it cannot know that we are done using the cursor.

      The cursor will be cleaned up on the server side when the transaction is finished or the MaapiCursor is garbage collected.

      But, if the transaction is kept open and we create new cursors over and over again or perhaps keep them in a list, preventing them from being garbage collected, they will still be present on the server side if not iterated to the end, effectively creating a resource leak.

      Calling this function explicitly cleans up resources on the server.