Most parties involved in the Object Management Group’s process for deciding on an object request broker would like there to be some way to incorporate both technologies left in the ring that from Hewlett-Packard Co, Sun Microsystems Inc and NCR Corp on the one hand and that from Digital Equipment Corp on the other. Ironically, the one other submission that could have provided the technology to bring this unity about has already bowed to pressure and left the ring. The tiny UK company Architecture Projects Management Ltd, whose Ansaware technology lies at the heart of both the Hewlett-Packard and DEC submissions, withdrew last month but could use its technology to bring the two sides together. There are significant differences between the approaches of the two camps: those adopting NewWave take an early binding approach, which means that the interface for both the client and the server is pre-determined so that the developer needs only to put the interface code into the server. On the client side, a pre-determined interface means that the coding can be very compact. The advantage bestowed by this approach is a faster, more secure system which can be easily controlled and checked. DEC, on the other hand, has adopted a late binding approach, which means that no prior negotiations are fixed – every server is prepared to service any request, which means that each object must contain a description of what it is, because the server needs to look at each object and unwrap it. This leads to a slower, less secure system. However, DEC’s Application Control Architecture will undoubtedly be developed to define new management procedures that will incrementally go to each object, describing interfaces and carrying out early checking, activated at run-time. In other words DEC’s approach will probably grow to incorporate polymorphic typing, making it easier for program debugging and verification. This is something that cannot be supported in Hewlett-Packard’s Class Definition Language. Consequently, because of the potential sophistication of the HyperDEC submission it would be shortsighted to reject it altogether in favour of the opposing Distributed Object Management Facility. So how could the two approaches be wed together? Andrew Herbert, technical director of Architecture Projects, believes that it will be no harder to add the DEC world to the Distributed Object Management Facility than it will be to bring NCR into the fold. All three – Hewlett-Packard, Sun and NCR – use different remote procedure calls, which means that they have different data representation and different ways of locating objects. For example, both Sun and NCR use name servers, while Hewlett-Packard uses message broadcast servers. Therefore, the trio will have to build gateways between the three systems and there is no logical reason why another gateway should not be built to embrace the DEC world. Herbert says that Architecture Projects is already in a position to offer the requisite technology in the form of its Ansaware product, since it offers a common interface for programmers to write to while the Ansa Trader can convey requests and answers across multiple protocol domains, thus shielding the developer from the variety of remote procedure calls. Herbert commented drily that were the liaisons springing up among the Object Management Group members more than purely political, submitters would be approaching his company with this solution in mind. – Katy Ring
