In Progress at OMG: Extensible and Dynamic Types

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href="http://portals.omg.org/dds">DDS is popular,

and addresses a number of href="http://www.rti.com/solutions/">important use

cases that are not addressed by other specifications,

but that doesn't mean it's perfect. The DDS

community - including both href="http://www.rti.com/industries/">customers and

href="http://portals.omg.org/dds/VendorsPage">vendors

- is active within the href="http://www.omg.org/">OMG to address additional

areas in need of standardization. I thought I'd share

one of those areas now.

One of the really powerful things about DDS is that it

brings to distributed systems the same kind of type safety that

you'll find in local applications. In addition to

reducing errors, this href="http://blogs.rti.com/2009/04/30/data-transparency-why-you-should-care/">deep

knowledge of data types can improve performance and

resource usage by reducing the number of data copies in the

system and easing integration with other field- and type-aware

technologies, including href="http://www.rti.com/products/dds/RTIReal-TimeConnect.html">relational

databases and even href="http://www.rti.com/products/dds/microsoft-excel.html">Microsoft

Excel.

But as systems evolve over

time, type definitions can evolve too, and it's

important that applications that are already deployed

don't break as the types used by new applications

change. It's also desirable to ease the development of

infrastructure or cross-cutting components - like href="http://www.rti.com/products/developer_platform/index.html">tools,

href="http://www.rti.com/products/dds/rtirecorder.html">recorders,

generic data routing and transformation facilities, and others

- that shouldn't be tied to specific data

types. DDS users have been solving these problems in a variety of

ways for some time, and href="http://www.rti.com/products/dds/RTIDDS.html">some

implementations address them already, but

it's time for a standardized

solution.

To that end, the OMG is working on a

new specification, Extensible and Dynamic Topic Types

for DDS, that will provide additional capabilities for

the following:

A clarified and
extended type system that incorporates keys and extensibility as

first-class concepts
An API for the
definition of new data types at run-time without code

generation
A reflective API for the
construction, inspection, and manipulation of data samples based

on dynamic type definitions
The ability to
define data types declaratively using not only OMG IDL but XML

and XML Schema (XSD) as well for easier integration with href="http://www.rti.com/solutions/enterprise-messaging.html">enterprise

systems