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corba比较入门级的介绍详细间接了corba访问发布各种细节。

<H4><FONT COLOR="#000077">Transportation Domain Task Force</FONT></H4>
<P>It is the mission of the Transportation Domain Task Force to promote the development
and use of transportation-related systems that incorporate OMG specifications and
technologies; to identify relevant standards, business objects, components, and technologies
in the field of transportation, and to disseminate this information to the OMG; to
work within the OMG committees and task forces to ensure that the CORBA, CORBAservices,
CORBAfacilities, Business Object, and domain specifications are conducive to the
needs of the transportation industry; to recruit additional Transportation DSIG membership
from corporations in the transportation systems development community; and to establish
a global forum for the free exchange of distributed object systems development ideas
amongst the various members of the transportation community and its partners.</P>
<P>The Transportation Domain Task Force, one of the newest Task Forces in the OMG,
has issued the following RFI:

<UL>
	<LI><I>CORBAtransport RFI</I>. This RFI solicits information about requirements,
	projects, and products that will provide guidance for transportation-related object
	system interoperability. The overall goal will be to adopt vendor-neutral common
	interfaces. Responses to this RFI will be used to define one or more RFPs that will
	solicit OMG IDL interfaces and other corresponding materials, such as semantic descriptions,
	sequencing, and timing constraints. CORBAtransport intends to produce specification
	sets in at least four major vertical domains (air, marine, highway, and rail) and
	a common horizontal specification across the breadth of the transportation domain.
</UL>

<H3><A NAME="Heading7"></A><FONT COLOR="#000077">What It All Means</FONT></H3>
<P>Certainly the OMG is hard at work enhancing current specifications and creating
new ones. But what does it all mean? In particular, who stands to benefit from the
products of the various Technology Committees and Task Forces?

<UL>
	<LI><I>Everyone</I>. That is, all developers of CORBA applications will benefit from
	many of the enhancements being made to CORBA. The Platform Technology Committee Task
	Forces--namely, the ORB and Object Services Platform Task Force and the Analysis
	and Design Platform Task Force--are working on specifications that will benefit virtually
	all CORBA developers. Features such as a CORBA component model, the capability to
	pass objects by value as well as by reference, persistent CORBA objects, a scripting
	language for CORBA objects, and printing capability are useful to a wide variety
	of developers.<BR>
	<BR>
	
	<LI><I>Developers using other technologies</I>. Developers using Microsoft's COM
	object model will benefit from enhanced interoperability between COM and CORBA objects;
	those using the DCE-distributed computing model will realize similar benefits. And,
	of course, Java will enjoy improved interoperability with CORBA, particularly with
	the capability to convert Java interfaces to IDL interfaces.<BR>
	<BR>
	
	<LI><I>Users of electronic commerce</I>. As mentioned previously, electronic commerce
	has the potential to become a killer app for the Internet, and CORBA will be there.
	Thus, anyone wishing to take advantage of electronic commerce capability stands to
	benefit from the work being done by the Electronic Commerce Domain Task Force in
	this area.<BR>
	<BR>
	
	<LI><I>Developers of vertical applications</I><B>.</B> A great deal of work is being
	done to support a variety of vertical industry applications. The standards being
	developed for these markets will promote interoperability between such applications.
</UL>

<P>Again, as of the time of this writing, the OMG had not yet specified the contents,
or even an availability date, of CORBA 3.0. Therefore, which of the specifications
described here will be included in the next major CORBA release is anybody's guess.
When these specifications do become available, however, all CORBA developers will
be the winners.
<H2><A NAME="Heading8"></A><FONT COLOR="#000077">Looking Beyond</FONT></H2>
<P>The current Requests for Proposals and Requests for Information issued by the
various Task Forces within the OMG give a good indication of where CORBA is heading
in the near future. But what about beyond that? How will CORBA affect the development
of distributed applications in the not-so-near future? And what challenges will it
face? Although it is difficult to predict anything in the area of software development
technology, this section addresses some of these questions.
<H3><A NAME="Heading9"></A><FONT COLOR="#000077">CORBA Development in the Future</FONT></H3>
<P>Despite its current shortcomings, CORBA is nonetheless a very powerful development
tool already. It still can stand to see some improvement, however, particularly in
one area: So far, nobody has ever accused CORBA of being too<I> </I>easy to develop
with.</P>
<P>Face it, CORBA's awesome power, plus its unmatched cross-platform and cross-language
capabilities, come at a price. Developing for CORBA means learning to develop for
yet another platform, as it were. The benefits that come with learning and applying
this skill are immense, but in this age of rapid application development, emphasis
is often placed on the speed of deployment of an application rather than on the power
and robustness of a design. If CORBA is to continue to enjoy success as a development
platform, it must learn to play in this world of instant software development.</P>
<P>Does this mean sacrificing CORBA's power, cross-platform capability, or robustness
for ease of use? Of course not, although development tools could go a long way towards
making CORBA application development easier on the developer. Already, such tools
are starting to appear, and initiatives such as the ORB and Object Services Platform
Task Force's Java to IDL RFP suggest that additional strides will be made towards
making CORBA more seamless with application development.</P>
<P>The <I>seamless</I> concept will eventually be the key to CORBA's success. Although
the use of some CORBA services, facilities, and the like will always require some
developer knowledge, the developer should be insulated as much as possible from the
plumbing of a CORBA application. Details of memory management, reference counting,
and perhaps of IDL itself, should be handled by the development tools themselves,
invisible to most developers. (Granted, a developer should still be able to drill
down to this level of detail when desired, and a good development tool will always
enable this level of interaction.) Freed from having to worry about the details of
implementation, the developer can concentrate more on the design of the application
itself.</P>
<P>In short, CORBA is already at the point where some very impressive things can
be done with it. Additional features will push the usefulness of CORBA even farther,
but to ensure CORBA's success, development tool vendors must provide tools that make
CORBA application development easier than ever. (In the meantime, publishers are
happy to bring to you such books as <I>Sams' Teach Yourself CORBA in 14 Days</I>!)
<H3><A NAME="Heading10"></A><FONT COLOR="#000077">Challenges Facing CORBA</FONT></H3>
<P>Despite the power and capability of the CORBA architecture and the Object Management
Architecture surrounding it, CORBA still faces a number of challenges to its success.
These challenges come in the form of competing technologies, or in the very process
by which CORBA and related specifications are adopted. This section will briefly
describe some of the challenges facing CORBA today.
<H4><FONT COLOR="#000077">Microsoft DCOM</FONT></H4>
<P>Not surprisingly, CORBA is not without its competition. Although CORBA has the
backing of almost the entire industry, including some very big players, its universal
acceptance faces at least one major obstacle. This challenge comes in the form of
another distributed object model from a vendor that enjoys an extremely dominant
position in the industry. The vendor, of course, is none other than Microsoft, which
is heavily pushing its Distributed Component Object Model (DCOM) as a de facto standard
for a distributed computing platform.</P>
<P>Microsoft is quite clear regarding its position on CORBA, the open standard backed
by just about every other player in the industry. Perhaps this position is best summed
up in the words of COM Product Manager Cornelius Willis, as reported by <I>InfoWorld
Electric</I> on August 18, 1997: &quot;Of course, we want COM3--now known as COM+--to
make CORBA irrelevant.&quot; (The original article is available at <I>InfoWorld Electric</I>'s
Web site at <A HREF="http://www.infoworld.com/cgi-bin/displayArchives.pl?970818.wsoft.htm"><TT>http://www.infoworld.com/cgi-bin/displayArchives.pl?970818.wsoft.htm</TT></A>.)
Apparently, Microsoft prefers to extend its already expansive industry domination
to include distributed computing standards as well, rather than support a widely
accepted industry standard. To its credit, Microsoft has turned over parts of its
COM, DCOM, and ActiveX technologies to The Open Group, an independent standards organization,
and is partnering with Software AG to provide DCOM implementations on operating systems
other than Windows. (More details are available at <A HREF="http://www.activex.org/ "><TT>http://www.activex.org/</TT></A>
and <A HREF="http://www.softwareag.com/corporat/dcom/default.htm"><TT>http://www.softwareag.com/corporat/dcom/default.htm</TT></A>.)</P>
<P>Of course, Microsoft is welcome to compete in this space. If anything, competition
will help to keep the OMG and CORBA product vendors on their toes, providing the
best possible specifications, implementations, and interoperability they can. However,
given the near ubiquity of Microsoft's operating systems--and, by extension, DCOM--backers
of CORBA will be fighting an uphill battle against Microsoft's leveraging of one
of its platforms to create another. However, there is hope--CORBA currently enjoys
some advantages over DCOM, as outlined in an article available at the OMG Web site
at <A HREF="http://www.omg.org/news/activex.htm"><TT>http://www.omg.org/news/activex.htm</TT></A>.
Another OMG article, a response to a report published by the UK-based analyst group
Ovum, also provides some relevant information comparing CORBA and DCOM; the article
is available at <A HREF="http://www.omg.org/news/pr97/ovumpr.htm"><TT>http://www.omg.org/news/pr97/ovumpr.htm</TT></A>.
<H4><FONT COLOR="#000077">Other Challenges</FONT></H4>
<P>Of course, there are other challenges facing CORBA as well. Consider, for example,
the issues involved with managing an organization with more than 750 members. Granted,
not all the OMG members vote on proposals, but the associated overhead is not insignificant.
One of the OMG's greatest strengths--its strong backing by the industry--might also
be one of its greatest weaknesses because the resulting bureaucracy can slow the
development and acceptance of new specifications. The OMG has done exceptionally
well so far, especially considering its size. With competition from Microsoft's DCOM,
the OMG will need to take great care to ensure that the organization doesn't collapse
under its own weight, possibly taking CORBA with it.
<H2><A NAME="Heading11"></A><FONT COLOR="#000077">Summary</FONT></H2>
<P>CORBA has already come a long way. With a membership of more than 750 and still
growing, the OMG has definitely achieved a position of great relevance in the marketplace.
CORBA as a standard has been growing and maturing for more than seven years now--an
eternity in computer time. CORBA products are available on a wide variety of platforms
and operating systems from dozens of vendors. (Among the platforms supported by CORBA
are AS400, HP-UX, MacOS, MS-DOS, MVS, OpenVMS, OS/2, SunOS and Solaris, Windows 3.x,
Windows 95, Windows NT, and many flavors of UNIX not already mentioned.) Clearly,
CORBA has grown from its humble beginnings into an established, mature platform for
distributed application development.</P>
<P>CORBA isn't done growing; new capabilities and enhancements are being added all
the time. Today you've seen some of the enhancements currently proposed, from horizontal
features such as a CORBA object model, support for various languages, and support
for passing objects by value, to specifications for vertical facilities such as the
healthcare, telecommunications, and manufacturing industries. The OMG has big plans
for CORBA, and with the backing of a plethora of vendors producing CORBA products,
these plans are being realized. CORBA has already become a powerful, robust platform
for the development of distributed enterprise applications and is well on its way
to becoming far more useful than it already is. In the future, not only will CORBA
become even more powerful and robust, but it will also become more seamlessly integrated
with application development. The future certainly has some exciting things in store
for CORBA and its developers.</P>
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