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1.1     ! root        1: \documentstyle [small,blackandwhite] {NRslides}
        !             2: 
        !             3: \author {S.E. Kille \\
        !             4: Department of Computer Science \\
        !             5: University College London}
        !             6: 
        !             7: \date {October 1988}
        !             8: \raggedright
        !             9: \title {ISODE --- Further Comments}
        !            10: 
        !            11: \begin {document}
        !            12: 
        !            13: \maketitlepage
        !            14: 
        !            15: \begin {bwslide}
        !            16: \ctitle {Overview}
        !            17: \begin {itemize}
        !            18: \item To complement Marshall Rose's talk
        !            19: \item To give a European perspective
        !            20: \item To give some more details on lower layers and ASEs (other talks focus
        !            21: on the applications)
        !            22: \end {itemize}
        !            23: \end {bwslide}
        !            24: 
        !            25: \begin {bwslide}
        !            26: \ctitle {Coding Approaches}
        !            27: \begin {itemize}
        !            28: \item Procedural interfaces corresponding to service definitions
        !            29: \begin {itemize}
        !            30: \item Easy to understand
        !            31: \item Flexible
        !            32: \item General
        !            33: \item Sometimes wrong (e.g. RTS)
        !            34: \end {itemize}
        !            35: 
        !            36: \item Full implementations of the protocols and services
        !            37: 
        !            38: \item All ASEs and lower layers can be used asynchronously
        !            39: \begin {itemize}
        !            40: \item Must be suitable support from Transport or Network interface (e.g.,
        !            41: Sockets)
        !            42: \item Needs to have sufficient kernel buffering for OPDU writes
        !            43: \item ISODE deals with OPDU read buffering
        !            44: \end {itemize}
        !            45: 
        !            46: \item Flexible layering 
        !            47: \end {itemize}
        !            48: \end {bwslide}
        !            49: 
        !            50: 
        !            51: 
        !            52: \begin {bwslide}
        !            53: \ctitle {What about the X.25}
        !            54: \begin {itemize}
        !            55: 
        !            56: \item X.25/CONS is essential for real OSI 
        !            57: \begin {itemize}
        !            58: \item Statement of religion
        !            59: \item TCP/IP or TP4/CLNS are not suitable/desirable for WANs
        !            60: \end {itemize}
        !            61: 
        !            62: \item Current implementations
        !            63: \begin {itemize}
        !            64: \item SUNOS + SUNLINK X.25
        !            65: \item Vax + BSD UNIX + UBC Code + DMF 32
        !            66: \item Vax + Ultrix + CAMTEC Dexpand with X.25 or Pink Book (latter is not a
        !            67: product).    
        !            68: \item Straightforward to add in others
        !            69: \begin {itemize}
        !            70: \item Easiest if socket-like interface
        !            71: \item Device-like interface possible
        !            72: \end {itemize}
        !            73: 
        !            74: \end {itemize}
        !            75: \end {itemize}
        !            76: \end {bwslide}
        !            77: 
        !            78: 
        !            79: \begin {bwslide}
        !            80: \ctitle {What about the X.25 (2)}
        !            81: 
        !            82: (or why TCP/IP is used on UNIX LANs)
        !            83: 
        !            84: 
        !            85: \begin {itemize}
        !            86: 
        !            87: \item Problems with UNIX X.25
        !            88: \begin {itemize}
        !            89: \item Not sufficient coverage
        !            90: \item No standard interface
        !            91: \item Poor performance
        !            92: \item Not robust
        !            93: \item Some interfaces will not allow for asynchronous working 
        !            94: \item Problem with the implementations, not X.25
        !            95: \end {itemize}
        !            96: 
        !            97: \item What is needed
        !            98: \begin {itemize}
        !            99: \item Standard interface (POSIX transport may give this)
        !           100: \item Pink Book
        !           101: \item Realistic Performance
        !           102: \end {itemize}
        !           103: 
        !           104: \item ISODE supports X.25, but X.25 does not support ISODE
        !           105: 
        !           106: \end {itemize}
        !           107: \end {bwslide}
        !           108: 
        !           109: \begin {bwslide}
        !           110: \ctitle {Transport}
        !           111: \begin {itemize}
        !           112: \item TP0 is a part of ISODE
        !           113: \item TP0++ over TCP in ISODE
        !           114: \begin {itemize}
        !           115: \item RFC 1006
        !           116: \item Best choice in LAN environment (currently)
        !           117: \end {itemize}
        !           118: 
        !           119: \item Straightforward to interface to other Transport {\em Services}
        !           120: 
        !           121: Variety of application disciplines:
        !           122: \begin {itemize}
        !           123: \item Use of Transport Daemon (tsapd) 
        !           124: \item Application Servers
        !           125: \item Callback
        !           126: \item Multithreading
        !           127: \end {itemize}
        !           128: 
        !           129: \item TP0 extensively tested
        !           130: \end {itemize}
        !           131: \end {bwslide}
        !           132: 
        !           133: \begin {bwslide}
        !           134: \ctitle {Session}
        !           135: 
        !           136: \begin {itemize}
        !           137: \item Full Session Protocol and Service implemented
        !           138: \item Substantial interworking tests
        !           139: \item Version 2 (88) in ISODE 4.0 
        !           140: \end {itemize}
        !           141: 
        !           142: \end {bwslide}
        !           143: 
        !           144: 
        !           145: \begin {bwslide}
        !           146: \ctitle {Presentation}
        !           147: \begin {itemize}
        !           148: \item Most of Protocol and Service implemented
        !           149: \item IS
        !           150: \item Simple and Full encoding
        !           151: \item X.410 mode
        !           152: \item Some interworking (FTAM + VTP)
        !           153: \end {itemize}
        !           154: 
        !           155: \end {bwslide}
        !           156: 
        !           157: 
        !           158: 
        !           159: \begin {bwslide}
        !           160: \ctitle {ASN.1}
        !           161: 
        !           162: \begin {itemize}
        !           163: \item Not bound to presentation layer
        !           164: \item Special Tools (discussed elsewhere)
        !           165: \item Abstract representation as C structures as intermediate form 
        !           166: \item Used extensively
        !           167: \item Tools have handled a wide range of specifications
        !           168: \end {itemize}
        !           169: \end {bwslide}
        !           170: 
        !           171: \begin {bwslide}
        !           172: \ctitle {ACSE}
        !           173: \begin {itemize}
        !           174: \item Full implementation (lots of parameters)
        !           175: \item The interface used by the application
        !           176: \item AE Titles still a problem
        !           177: \begin {itemize}
        !           178: \item OBJECT IDENTIFIER used by stub directory
        !           179: \item Distinguished Name will be used in QUIPU context
        !           180: \end {itemize}
        !           181: 
        !           182: \end {itemize}
        !           183: \end {bwslide}
        !           184: 
        !           185: 
        !           186: 
        !           187: \begin {bwslide}
        !           188: \ctitle {RTS}
        !           189: \begin {itemize}
        !           190: \item 1988 and 1984 (X.410)
        !           191: \item Some interworking tests of X.410 done
        !           192: \item Not spooled (i.e. RTS application has to do the work)
        !           193: \item New interface being done
        !           194: \end {itemize}
        !           195: \end {bwslide}
        !           196: 
        !           197: 
        !           198: \begin {bwslide}
        !           199: \ctitle {ROS}
        !           200: 
        !           201: 
        !           202: \begin {itemize}
        !           203: \item Full implementation
        !           204: \item  ROSY/POSY facilitate use
        !           205: \item  Various versions 
        !           206: \begin {itemize}
        !           207: \item X.410 
        !           208: \item ECMA ROS (BCS Session)
        !           209: \item 1988 ROS (RTS optional)
        !           210: \end {itemize}
        !           211: 
        !           212: \item Common interface, except for initialisation
        !           213: 
        !           214: \item ECMA ROS used by THORN
        !           215: 
        !           216: \item 1988 ROS (no RTS) used by other ROS applications
        !           217: \end {itemize}
        !           218: \end {bwslide}
        !           219: 
        !           220: 
        !           221: 
        !           222: \begin {bwslide}
        !           223: \ctitle {Performance}
        !           224: \begin {itemize}
        !           225: \item Full implementation leads to large processes:
        !           226: \begin {itemize}
        !           227: \item Minimum 300kbyte
        !           228: \item DSA 500 kbyte
        !           229: \item FTAM 800 kbyte
        !           230: \end {itemize}
        !           231: 
        !           232: \item Substantial effort to avoid byte copying
        !           233: \begin {itemize}
        !           234: \item qbufs
        !           235: \item PPPPPP
        !           236: \end {itemize}
        !           237: 
        !           238: \item Low bulk transfer overheads
        !           239: \begin {itemize}
        !           240: \item  ROS is 12\% slower than raw TCP
        !           241: \item  FTAM is 8\% slower than Arpanet FTP
        !           242: \item  More CPU intensive
        !           243: \item  X.25 too slow to be relevant
        !           244: \end {itemize}
        !           245: 
        !           246: \item Initialisation not so fast
        !           247: \begin {itemize}
        !           248: \item Typically a few seconds
        !           249: \item Paging in process is a big overhead
        !           250: \end {itemize}
        !           251: 
        !           252: \end {itemize}
        !           253: \end {bwslide}
        !           254: 
        !           255: 
        !           256: \begin {bwslide}
        !           257: \ctitle {How good is it really?}
        !           258: \begin {itemize}
        !           259: \item Does not claim to be production quality
        !           260: \item Better than much ``production software'' I have seen
        !           261: \item Code Quality
        !           262: \begin {itemize}
        !           263: \item Few comments
        !           264: \item Well structured
        !           265: \item Long variable names
        !           266: \item Documented (700 pages)
        !           267: \item Careful version control
        !           268: \item Thorough testing of releases
        !           269: \end {itemize}
        !           270: 
        !           271: \item Ideal for experimentation and early services
        !           272: 
        !           273: \item Possible drawbacks for products
        !           274: \begin {itemize}
        !           275: \item Lower layers and ASEs not tuned for specific applications
        !           276: 
        !           277: \item ASN.1 Tools
        !           278: \begin {itemize}
        !           279: \item Good overall functionality, but
        !           280: \item Too much code output
        !           281: \item Memory based
        !           282: \item Need SOPY
        !           283: \end {itemize}
        !           284: 
        !           285: \end {itemize}
        !           286: 
        !           287: 
        !           288: \end {itemize}
        !           289: 
        !           290: \end {bwslide}
        !           291: 
        !           292: \begin {bwslide}
        !           293: \ctitle {Other Applications}
        !           294: \begin {itemize}
        !           295: \item NRS Lookup Protocol
        !           296: \item IDIST (ROS based RDIST)
        !           297: \item Management Protocols
        !           298: \item ODA/ODIF
        !           299: \end {itemize}
        !           300: 
        !           301: \end {bwslide}
        !           302: 
        !           303: 
        !           304: \end {document}

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