Returns the value of a named Field (null is a legal value too). Returns
null also if the Field is not reported in the ItemEvent.
Any value can be expressed as either a byte array or a String:
- If a value is supplied as a byte array, it will be considered
as an ISO-8859-1 (ISO-LATIN-1) representation of a string, so that
the clients will be able to receive the value as a string object.
A special case is that of binary representations of AMF objects,
which can be received by the Flex Client Library in binary form.
As another special case, the mandatory fields for COMMAND Mode,
named "key" and "command", cannot be supplied as byte arrays.
- If a value is supplied as a String, it will be received as an
equivalent string object by the client. This, however, involves
an internal conversion to a byte array in order to send the update;
this makes supplying values as String less efficient than supplying
them as byte arrays, though the latter method is restricted to the
ISO-8859-1 (ISO-LATIN-1) character set.
Lightstreamer Kernel will call this method at most once for each Field
(unless events logging is enabled) and may not call this method at all
for some Fields. So, if performing any data conversion is required
in order to extract Field values, it may be convenient to do it on
demand rather than doing it in advance.