============
Adding Nodes
============

Adding Folder Node
------------------


UA Folder in the OPC-UA Address space is of the type Folder object and
is based on the Object NodeClass. The purpose with this object is to
organize nodes into a tree structure.

To create a Folder node, specify the following attributes:

  .. literalinclude:: examples/client/client_add_nodes.lua
      :language: lua
      :lines: 50-80

  `Full source <_static/client/client_add_nodes.lua>`__

Adding Variables
----------------

A Variable in OPC-UA is a node in the address space with a set of predefined
attributes:

  .. literalinclude:: examples/client/client_add_nodes.lua
      :language: lua
      :lines: 82-99

  `Full source <_static/client/client_add_nodes.lua>`__

.. _valuerank_def:

Variable Node Attributes
------------------------

To add a new variable node, you need to set the following parameters:

  **ParentNodeId** (type :ref:`NodeID<node_id_type>`)
    Parent's node identifier.

  **ReferenceTypeId** (type :ref:`NodeID<node_id_type>`)
    Parent's reference type identifier.

  **RequestedNewNodeId** (type :ref:`NodeID<node_id_type>`)
    NodeID for the new node. If NodeId equals to ua.NodeId.Null, then the actual
    identifier will be automatically assigned by server.

  **BrowseName** (type QualifiedName)
    Internal name for the node. This name is used in the
    TranslateBrowsePathsToNodeIdsservice to resolve NodeId by path from some
    nodes.

  **NodeClass**  (value from table ua.Types.NodeClass)
    Node class: Variable, Object, DataType. Only Variable node class
    is currently supported.

  **DisplayName** (type LocalizedText)
    Clients use this attribute if they want to display the name of the node to the user. Can be localized.

  **Description** (type LocalizedText)
    The optional description attribute explains the purpose with the node using localised text.

  **WriteMask** (type UInt32)
    Bit mask. Every bit defines ability to change corresponding attribute.

  **UserWriteMask** (type UInt32)
    Bit mask. Every bit defines ability to change corresponding attribute for
    current user.

  **Value** (:ref:`DataValue<data_value_type>`)
    Initial value of a variable node.

  **DataType** (type :ref:`NodeID<node_id_type>`)
    Identifier of a node of NodeClass DataType that describes structue of a
    value. For example encoding/decoding in binary, json, xml formats. This
    may be an ID of a node of simple type (Int32, UInt,Float, etc), and
    complex structures (for example certificate, ApplicationDescription,
    BuildInfo).

  **ValueRank** (type Int32)
    The value rank for the field.
    It shall be Scalar (-1) or a fixed rank Array (>=1).
    There are next predefined values:

      * ScalarOrOneDimension = -3,
      * Any = -2,
      * Scalar = -1,
      * OneOrMoreDimensions = 0,
      * OneDimension = 1,

    Greater values are number of dimensions: 2(matrix),3,4..

  **ArrayDimensions** (array of UInt32)
    Array dimensions of the value. For example: {2,2} describes square matrix
    with size 2*2.

  **AccessLevel** (type Byte)
    The AccessLevel Attribute is used to indicate how the Value of a
    Variable can be accessed (read/write) and if it contains current
    and/or historic data.


  **UserAccessLevel** (type Byte)
    Write mask of current user


Object node attributes
----------------------

To add a new Folder node, you need to set the following parameters:

  **ParentNodeId** (type :ref:`NodeID<node_id_type>`)
    Parent's node identifier.

  **ReferenceTypeId** (type :ref:`NodeID<node_id_type>`)
    Parent's reference type identifier.

  **RequestedNewNodeId** (type :ref:`NodeID<node_id_type>`)
    NodeID for the new node. The identifier will be automatically
    assigned by server if NodeId equals ua.NodeId.Null.

  **BrowseName** (type QualifiedName)
    Internal name for the node. This name is used in the
    TranslateBrowsePathsToNodeIdsservice to resolve NodeId by path from some
    nodes.

  **NodeClass**  (value from table ua.Types.NodeClass)
    Node class: Variable, Object, DataType. Only Variable node class
    is currently supported.

  **DisplayName** (type LocalizedText)
    Clients use this attribute if they want to show the name of the node to the user. Can be localized.

  **Description** (type LocalizedText)
    The optional description attribute explains the purpose with the node using localised text.

  **WriteMask** (type UInt32)
    Bit mask. Makes it possible for a client to write the Attributes of the Node.

  **EventNotifier** (type Byte)
    Event notifier.

Results
-------

The result from an OPC UA call will be an array. Every element of the
array will be a table with two fields: Status code for current node
and Identifier of added node.

Every element of the array contains a table with the following fields:

  **StatusCode**
    Status code of adding corresponding node.

  **AddedNodeId**
    Identifier of added node. Server automatically assign an identifier
    for the node if not included. In other case will be returned
    identifier passed in parameters. Nil in case of error.