18. Multiple files capabilities

There are a lot of use cases for which an Amelet HDF instance could be split up into several files :

• The mesh are in an another file because it has been generated and stored separately. It is also better for the re-usability of objects.
• A large arraySet has been generated by a simulation.

Amelet HDF offers a flexible means to handle multiple files.

18.1. The externalElement category

The /externalElement category is an HDF5 group, its children are HDF5 string (n x 3) datasets :

• The first column contains elements names used in the Amelet HDF instance but defined in another (external) Amelet HDF instance.
• The second column contains the file’s name the element is defined in.
• The third column contains the name of the elements in the external file.

Note

The name of the children of /externalElement is not specified by Amelet HDF.

Example, consider the following Amelet HDF instances data.h5 and mesh.h5 :

data.h5/
|-- externalElement/
|   `-- $external_element
|-- simulation/
|-- link/
|   `-- $link_group[@type=dataOnMesh]
|       `-- link_instance[@subject=/physicalModel/volume/$diel1
|                         @object=/mesh/$gmesh1/$plane/group/$right-wing]
`-- physicalModel/
    `-- volume
        `-- $diel1

where data.h5:/externalElement/$external_element is :

/mesh/$gmesh1/$plane	mesh.h5	/mesh/$gmesh1/$mesh1
/mesh/$gmesh1/$wing	mesh.h5	/mesh/$gmesh1/$mesh2

and :

mesh.h5/
`-- mesh
    `-- $gmesh1
        |-- $mesh2
        `-- $mesh1
            |-- elementNodes
            |-- elementTypes
            |-- nodes
            |-- group
            |   |-- $field-location[@type=node]
            |   |-- $right-wing[@type=element]
            |   `-- $left-wing[@type=element]
            |-- groupGroup
            |   `-- $wings
            `-- selectorOnMesh
                |-- nodes
                `-- elements

The mesh data.h5:/mesh/$gmesh1/$mesh1 declared (and used) in the instance data.h5 is really defined in the instance mesh.h5:/mesh/$gmesh1/$mesh1.

From this point, elements which appear in data.h5 with a name beginning with /mesh/$gmesh1/$plane must be read from data.h5:/mesh/$gmesh1/$mesh1.

Note

With externalElement, it is possible to know all elements defined externally in one glance.

18.2. the linkDefinition attribute

A named element can have one optional attribute which drives toward the genuine location of its definition :

This attribute is linkDefinition : It is the absolute name of the element definition.

Example, consider the following Amelet HDF instances data.h5 containing two arraySet data.h5:/floatingType/e_field and data.h5:/floatingType/h_field :

data.h5/
`-- floatingType
    |-- e_field
    |   |-- data
    |   `-- ds
    |       |-- dim1
    |       `-- dim2
    `-- h_field
        |-- data
        `-- ds
            |-- dim1[@linkDefinition=/floatingType/e_field/ds/dim1]
            `-- dim2[@linkDefinition=/floatingType/e_field/ds/dim2]

In this example, the dimension of data.h5:/floatingType/h_field are defined from the dimension of data.h5:/floatingType/e_field.