org.dmd.dmc.conversion

Interface AttributeReadInterceptor

public interface AttributeReadInterceptor

The AttributeReadInterceptor allows for the insertion of attribute level data conversion. For instance, let's say you have an attribute that changes type from one version of the schema to another. When converting the existing data, you have to read the attribute as the original type and store it as the new type.

Method Summary

Modifier and Type	Method and Description
void	handleAttribute(DmcInputStreamIF dis, DmcAttribute<?> attr) Derived classes should perform whatever conversion logic is required on the specified attribute.

Method Detail

handleAttribute

void handleAttribute(DmcInputStreamIF dis,
                     DmcAttribute<?> attr)
              throws Exception

Derived classes should perform whatever conversion logic is required on the specified attribute.

For instance if the attribute changed from a float to a double, you would want to read a float from the input stream and write it into the attribute (making it a double).

Exactly what you do in this process will be dictated by the schema changes you've made.

It is expected that you will read all data from the input stream that is associated with the attribute in question, whether it is single or multi-valued. So, obviously, you should be familiar with the serializeValue()/deserializeValue() functions associated with the the DmcType??? data type in question.

For multi-valued attributes, the next piece of data in the input stream will be the number of values that need to be deserialized. Have a look at DmcAttribute.deserializeIt() to see how this is done.

Parameters:

dis - the input stream.

attr - the attribute container that was constructed at the current version of the schema.

Throws:

Exception