DDS — DDS ISSUE# 34] Initial data when DataWriter appears

Ref-90 Initial_data_from_transient_or_persistent_data

The specification mentions that if the DURABILITY is set to TRANSIENT
or PERSISTENT a newly appearing DataReader would be able to get some
amount of history data.

However the precise semantics of this are not clear. For example is
the application allows to receive information as soon as the Reader is
active (perhaps from active writers) even before the historical data
has been received?

It would be desirable to offer the application some control about how
to initialize the reader when it first joins the system.

**PROPOSAL**

Introduce an operation DataReader:: get_historical_data(in Duration_t
max_time_to_wait);

This operation will block for a maximum of max_time_to_wait until the
system gets the initial data.

Introduce the ReturnCode_t "TIMEOUT" to section 2.1.1.1.

State that the get_historical_data operation will return OK if all the
initial data has been received. Otherwise it will return TIMEOUT if
the system cannot ensure that all historical data has been received.

see below