Package opendap.dap

Class DAS

  • All Implemented Interfaces:
    Serializable, Cloneable
    public class DAS
extends AttributeTable
    The Data Attribute Structure is a set of name-value pairs used to describe the data in a particular dataset. The name-value pairs are called the "attributes." The values may be of any of the OPeNDAP simple data types (DByte, DInt32, DUInt32, DFloat64, DString and DURL), and may be scalar or vector. (Note that all values are actually stored as string data.)

    A value may also consist of a set of other name-value pairs. This makes it possible to nest collections of attributes, giving rise to a hierarchy of attributes. OPeNDAP uses this structure to provide information about variables in a dataset.

    In the following example of a DAS, several of the attribute collections have names corresponding to the names of variables in a hypothetical dataset. The attributes in that collection are said to belong to that variable. For example, the lat variable has an attribute units of degrees_north. 

      Attributes {
      GLOBAL {
          String title "Reynolds Optimum Interpolation (OI) SST";
      }
      lat {
          String units "degrees_north";
          String long_name "Latitude";
          Float64 actual_range 89.5, -89.5;
      }
      lon {
          String units "degrees_east";
          String long_name "Longitude";
          Float64 actual_range 0.5, 359.5;
      }
      time {
          String units "days since 1-1-1 00:00:00";
          String long_name "Time";
          Float64 actual_range 726468., 729289.;
          String delta_t "0000-00-07 00:00:00";
      }
      sst {
          String long_name "Weekly Means of Sea Surface Temperature";
          Float64 actual_range -1.8, 35.09;
          String units "degC";
          Float64 add_offset 0.;
          Float64 scale_factor 0.0099999998;
          Int32 missing_value 32767;
      }
  }

    Attributes may have arbitrary names, although in most datasets it is important to choose these names so a reader will know what they describe. In the above example, the GLOBAL attribute provides information about the entire dataset.

    Data attribute information is an important part of the the data provided to a OPeNDAP client by a server, and the DAS is how this data is packaged for sending (and how it is received).

    See Also:
    DDS, AttributeTable, Attribute, Serialized Form