rick@cs.arizona.edu (Rick Schlichting) (06/11/91)
Richard D. Schlichting (rick@cs.arizona.edu) Associate Professor Department of Computer Science The University of Arizona Tucson, AZ 86721, USA [This report represents the personal opinion of the author, who was on sabbatical in Japan from Dec. 1989 through July 1990. The sabbatical was supported in part by grant INT-8910818 from the NSF U.S.-Japan Cooperative Science Program.] --------------------------------------------------------------------------- On Tuesday, I traveled to the west side of Tokyo to visit NTT Software Laboratories. I arrived at the closest station -- Mitaka on the Chuo line -- at about 9:30am and from there took a taxi to the labs. Once I arrived, the guard phoned my host, Dr. Naohisa Takahashi, who came to sign me in. The lab itself consists of about 10 relatively new buildings in a pleasant setting. Takahashi led me to his office, which is in one of the main buildings. His background in mainly in functional languages, but recently he has been a member of a distributed computing group and working on replay-style debugging of concurrent, functional programs. For about 1/2 hour or so, he introduced the labs to me, overviewing the structure and groups. He then took me into a lab with (mainly) Suns to meet two other researchers. One, Ken-Ichiro Murakami, first described NTT's internal network to me. The system is built on TCP/IP and is consciously modeled about Stanford's, from which they apparently received guidance. Among the interesting points made: -- Compared to the U.S., there is a general lack of network expertise in Japan. -- A fair amount of the network equipment they use is American (e.g., Cisco routers) since theyt have been used more and hence have been debugged. Good technical support is also an issue. -- They consider network connectivity to the U.S. as an important part of general computing infrastructure. They were the first Japanese affiliate of CSNet, to which they are connected using two separate commercial transport services. -- Their efforts at expanding their international computer networking is hampered somewhat by regulations put forth my the Ministry of Telecommunications and Post. The basic problem is that they are not authorized as an international carrier, and so are prohibited from transferring outside (i.e., non-NTT email) across the Pacific over their leased lines. They expect some regulatory relief in the next few years. Following that presentation, another engineer named Toshiharu Sugawara demonstrated a heuristic-based Cooperative LAN Diagnostic Expert System. (A paper on this appeared in the IEEE Phoenix Conf. on Computers and Communication last year.) The basic idea is that a person having network troubles (e.g., unable to connect) would use the program to determine the problem. There is one instance of the program running on each network segment and the pieces cooperate as needed to determine the problem. The basic rationale for the development of the program is the lack of enough trained technical people who can be relied on to manually diagnose the problem. My understanding is that the program is still in development and is not yet used on a daily basis. Next, we went to lunch at the Tsuken Club located in a different building. The building appeared to house a general cafeteria, but we ate in a private dining room. Joining us for lunch was Prof. Sam Toueg from Cornell, who had arrived in Tokyo the previous Friday to start a month long visit to NTT. Apparently, an NTT researcher had visited Cornell for a time the previous year, and so they in turn had invited Sam. It was of course nice to see Sam again, and the entire group of us had a quite enjoyable conversation over a very excellent continental-style lunch. My presentation on Psync came after lunch, followed by a presentation and demo of a software development environment for communication software by a Dr. Haruhisa Ichikawa. The basic goal of the work is to perform automatic generation of communication software from specs, especially in an incremental fashion as the specs evolve over time. The system includes a graphical display of the specs, which were written in a standard protocol description language The system also detects problems with updated specs such as inconsistencies and the like. The system runs on Sun workstations and is being done jointly with British Telecom. Although I am not an expert in this area, I found the demo fairly impressive. In response to a question, however, Dr. Ichikawa seemed rather skeptical that this would be adopted to develop real-life communications software at any point n the near term; he essentially said that development departments have their own established methods that would be very difficult to change. The final work described during my visit was a debugger for parallel and distributed programs. This research was being directed by my host Dr. Takashi, and the presenter was a young research engineer who was collaborated on the work named Yoshifumi Manabe. The system is based on a replay technique and the use of global predicates to establish breakpoints. Among other things, they have purused what appears to be some fairly theoretical work on what type of global predicates are feasible for use in such debuggers. He gave me a couple of papers (including one in English) that describe the work. Overall, the visit to NTT Software Labs was very enjoyable. My impression from their presentations is that all of the various projects are technically sound, and that they understand well the basic issues and background. I also believe that they grasped well and appreciated the material on Psync that I presented; this includes the fault-tolerance aspects, which is especially impressive since, as far as I could tell, they are not doing any work specifically in that area. I also got the feeling that NTT encourages international cooperation and publication (their visiting researcher program is also evidence of this.) [Addendum added June 6, 1991] The LAN diagnosis system mentioned above is now being used occasionally to fix network troubles in the Lab, and has proved to be a useful tool. Dr. Takahashi's current research interests are focusing on the debugging of parallel programs with shared data objects. ---------------------------------------- Dr. Naohisa Takahashi Senior Research Engineer Software Research Laboratory NTT Software Laboratories Nippon Telegraph and Telephone Corp. 9-11 Midori-cho, 3-Chome Musashino-shi, Tokyo 180 Japan