Recommended Support for Integration of CORBA to WWW Gateways

Existing approaches to integration of the Object Management Group's 
Common Object Request Broker Architecture (CORBA)  to the World Wide Web 
(WWW)  typically entail significant custom development in  high level 
programming languages.   This has resulted in a variety of
gateway mechanisms and proprietary scripting languages.  The newly
emerging CORBA to Java implementations offer significant development
flexibility and yield high quality interfaces.  However, abstraction,
interface design, and proper use of object-oriented technology are
required when using these tools to produce well architected systems and 
applications. Typical HTML page designers often do not possess these 
skills.

To make it easier for non-developers to access objects and access CORBA
data, generic interfaces are needed that permit the embedding of
references to CORBA data in HTML pages. Development of generic 
interfaces
that map CORBA objects to HTML are likely to prove unsuccessful without 
extensions to both.  Recommended extensions include standards 
and keywords/tags for embedding CORBA property 
data into HTML documents, standard metadata support for all data types 
contained in the CORBA environment, and use of that metadata by gateway 
software to call conversion services as necessary to support the limited 
data types supported by WWW clients.  Together, these will permit 
development of easy to use generic services that allow end users to 
access CORBA data in their HTML pages.

Embedded Property Data:  A standard tag for referencing CORBA data in
HTML needs to be added, along with a mechanism to support a variety of
property names and types.  Pre-processing of this data must take place 
in
the gateway, where all CORBA object references are resolved. Applet
based clients would not require embedded property data, but designers
would need ways to maintain references to the CORBA based data. 

Metadata Service:  For automated conversion of data, standard metadata
that includes data typing is required.   For generic services to be
built that uses that data, the Trader service can be utilized in
combination with the Naming service to provide the necessary access
to information.  Collectively, the services will need to include
standard data dictionary information including data names and types
for automated access to appropriate Conversion Services. 

Conversion Services:  Unless an applet based client environment with 
ubiquitously high network bandwidth and client performance develops,  
WWW clients are likely to continue to lack support for all data types 
that a CORBA environment might support.  For example, WWW clients are 
unlikely to support all types of imagery that a CORBA environment might 
support, so CORBA conversion services will be needed to convert data 
to data types that are reasonable for WWW clients.  CORBA WWW gateway 
developers will need to be aware of the data types that their 
environments can produce and obtain conversions to data types that they 
can expect their standard WWW clients to support.  Furthermore, CORBA
is being used extensively to integrate legacy systems that contain 
legacy and
proprietary data types. Simple conversions and embedding techniques must
be provided so that page developers can easily leverage these resources.

Ron Zahavi, Mitretek Systems, Inc., rzahavi@mitretek.org
John Marsh, Mitretek Systems, Inc., jmarsh@mitretek.org