From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,INVALID_DATE autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,fe9e900c40b08b36 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 1994-10-01 21:14:55 PST Newsgroups: comp.lang.ada Path: bga.com!news.sprintlink.net!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!cis.ohio-state.edu!news.sei.cmu.edu!abg From: abg@sei.cmu.edu (Anthony Gargaro) Subject: Re: 9X Distributed Annex? CORBA? Message-ID: <1994Oct1.115355.25895@sei.cmu.edu> Sender: netnews@sei.cmu.edu (Netnews) Organization: The Software Engineering Institute References: Distribution: comp Date: Sat, 1 Oct 1994 11:53:55 EDT Date: 1994-10-01T11:53:55-04:00 List-Id: In article , WOODRUFF@ec2226.addvax.llnl.gov writes: |> |> I have studied the RM's Distributed Annex, and I recognize that the |> language standard will allow me to build the system I need. However I |> am not aware of any implementation of the Annex. I have not seen any |> claim by the GNAT team that they are planning an Annex implementation. |> Validation of commercial compilers is likely to be higher priority to |> compiler businesses than building Annexes. Therefore my first question |> is "where and when am I likely to obtain an implementation of |> Distributed Annex?" A non-government academic/industrial initiative is ongoing to build an open systems prototype of the Distributed Systems Annex. Initially this will be implemented for the GNAT (with the cooperation of the NYU team for the core language support). The intent is to make this prototype available coincident with the currently planned final release of GNAT (ca 3Q'95). (The attentive listener to Dr. Reifer's briefing at the WAdaS this year would have heard this initiative mentioned.) |> The other standard that appears relevant to my intention is CORBA. I'm |> pretty uninformed about implementations of CORBA, so I'd welcome advice |> about what I should do to prepare for eventual use of these products. |> How will Ada interface to CORBA tools? Will CORBA implementations let me |> mix my application parts with components in other languages, or even |> with COTS software? Both CORBA and the Distributed Systems Annex support what is becoming popularly called "distributed objects" (or "network objects") by the distributed programming literati. One significant difference is that CORBA is language independent and requires that the CORBA Interface Definition Language (IDL) be mapped to the implementation language of each object. Consequently, the CORBA concept is to provide, through distributed objects, the seamless integration of multilingual heterogeneous distributed applications. (Note the current specifications do not detail the necessary interoperability to achieve this concept.) |> What is the relationship of CORBA to the distributed annex? If the two |> are complementary strategies, then what will I need to buy and what do I |> need to learn so I can plan my application? On the other hand if they |> are two competing paradigms, how can I choose between them, and how bad |> will be my punishment if I choose the wrong one? The two paradigms are very similar from an applications programmer's perspective. They may be viewed as complementary, providing a continuum of distributed programming capabilities. For an Ada 9X distributed application, where predictability and safety is more important than integrating a collection of cooperating heterogeneous components, the annex may be preferable. If this application has to be interconnected within the context of a larger CORBA-compliant application, then one partition of the Ada 9X application can be implemented as the application gateway. This gateway would use both the annex and the IDL mapping to Ada 9X; the other partitions would remain unchanged. Tucker has noted several ways in which the respective implementations may potentially coexist. For example, the PCS may be implemented using the ORB core facilities; this would allow IDL requests for an object's service to be routed to an Ada 9X implementation of a conforming distributed object. Note that there is an effort to fast track the CORBA/IDL as an ISO standard. Regardless of whether or not this is appropriate (given the linguistic lineage of the IDL), an IDL mapping to Ada 9X becomes increasingly critical to Ada 9X.