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1.1 root 1: % \begin{bwslide}
2: %\part {SESSION SERVICES}\bf
3: %\end{bwslide}
4:
5:
6: \begin{bwslide}
7: \part {SESSION SERVICES}\bf
8:
9: \vskip.5in
10: \diagram[p]{figureA-6}
11: \end{bwslide}
12:
13:
14: \begin{bwslide}
15: \ctitle {SESSION LAYER\\PURPOSE}
16:
17: \begin{nrtc}
18: \item ADD STRUCTURE TO DATA CIRCUIT PROVIDED BY TRANSPORT
19: \item MORE ``APPLICATIONS ORIENTED'' STREAM TO USER
20: \item ADD CONTROL MECHANISMS TO DATA EXCHANGE
21: \end{nrtc}
22: \end{bwslide}
23:
24:
25: \begin{bwslide}
26: \ctitle {SESSION}
27:
28: \vskip.5in
29: \diagram[p]{figureA-13}
30: \end{bwslide}
31:
32:
33: % \begin{bwslide}
34: %\ctitle {SESSION}
35: %
36: %\begin{nrtc}
37: %\item 22 SERVICES
38: %\item 50+ PRIMITIVES
39: %\item COMPLEX STATE MACHINE RULES
40: %\item QUITE COMPLEX COMPARED TO TRANSPORT SERVICE
41: %%\item PRIMITIVES PREFIXED WITH {\em S--\ldots}
42: %\end{nrtc}
43: %\end{bwslide}
44:
45:
46: % \begin{bwslide}
47: %\ctitle {USERS}
48: %
49: %\begin{nrtc}
50: %\item {\em SS--user} TYPICALLY A PRESENTATION ENTITY
51: %\item NOT ALWAYS THE CASE
52: % \begin{nrtc}
53: % \item 1984 MHS (X.400) USED RELIABLE TRANSFER TO DIRECTLY
54: % ACCESS SESSION
55: % \end{nrtc}
56: %\item SESSION PROVIDER INTERACTS WITH A SINGLE {\em SS-user} ENTITY
57: %\end{nrtc}
58: %\end{bwslide}
59:
60:
61: % \begin{bwslide}
62: %\ctitle {\em SS-users}
63: %
64: %\begin{nrtc}
65: %\item CONNECTION ESTABLISHMENT
66: % \begin{nrtc}
67: % \item CALLING {\em SS-user}
68: % \item CALLED {\em SS-user}
69: % \end{nrtc}
70: %\item ACTION INITIATION
71: % \begin{nrtc}
72: % \item REQUESTING {\em SS-user}
73: % \item ACCEPTING {\em SS-user}
74: % \end{nrtc}
75: %\item CONNECTIONS ARE SYMMETRIC
76: %\end{nrtc}
77: %\end{bwslide}
78:
79:
80: % \begin{bwslide}
81: %\ctitle {SESSION ADDRESSING}
82: %
83: %\begin{nrtc}
84: %\item {\em SS-user} ADDRESSED AT SESSION SERVICE ACCESS POINT (SSAP) BY:
85: %\item SSAP CONTENT:
86: % \begin{nrtc}
87: % \item SESSION SELECTOR
88: % \item TRANSPORT ADDRESS
89: % \end{nrtc}
90: %%\item SELECTOR IS A STRING OF OCTETS
91: %\item TRANSPORT ADDRESS IDENTIFIES A GIVEN SESSION ENTITY
92: %\item SESSION SELECTOR IDENTIFIES A SPECIFIC USER OF THAT ENTITY
93: %\end{nrtc}
94: %\end{bwslide}
95:
96:
97: % \begin{bwslide}
98: %\ctitle {U.S. GOSIP SESSION SELECTOR}
99: %diagram
100: %\end{bwslide}
101:
102:
103: % \begin{bwslide}
104: %\ctitle {SESSION ADDRESSING (cont.)}
105: %
106: %\begin{nrtc}
107: %\item DE-MULTIPLEXING ON nSAPs
108: % \begin{nrtc}
109: % \item KERNEL
110: % \item USER
111: % \end{nrtc}
112: %\item IMPLEMENTATION CONSIDERATION
113: %\end{nrtc}
114: %\end{bwslide}
115:
116:
117: % \begin{bwslide}
118: %\ctitle {SERIAL NUMBERS}
119: %
120: %\begin{nrtc}
121: %\item {\em OPTIONALLY} MAINTAINED DURING SESSION CONNECTION
122: %\item AVAILABILITY DEPENDS ON CONNECTION FUNCTIONALITY NEGOTIATIONS
123: %\item USED TO COORDINATE AND REFERENCE TRANSACTIONS ON CONNECTION
124: %\end{nrtc}
125: %\end{bwslide}
126:
127:
128: % \begin{bwslide}
129: %\ctitle {CONNECTION IDENTIFIER}
130: %
131: %\begin{nrtc}
132: %\item {\em SS-users} ASSIGN A UNIQUE IDENTIFIER TO A CONNECTION
133: %%\item {NOT A LOCAL MECHANISM SUCH AS A FILE DESCRIPTOR}
134: %\item TYPICALLY
135: % \begin{nrtc}
136: % \item EACH SYSTEM PROVIDES A HOST NAME
137: % \item CURRENT UTC TIME IS PROVIDED IN A COMMON PORTION
138: % \end{nrtc}
139: %\item USED TO RE--ESTABLISH BROKEN CONNECTIONS
140: %\end{nrtc}
141: %\end{bwslide}
142:
143:
144: \begin{bwslide}
145: \ctitle {SESSION PROVIDES}
146:
147: \begin{nrtc}
148: \item DIALOGUE CONTROL (TOKENS)
149: \item SYNCHRONIZATION (CHECKPOINTING)
150: \item ACTIVITY MANAGEMENT
151: \item EXCEPTION REPORTING
152: \item {\em TRANSPORT FUNCTIONALITY}
153: \end{nrtc}
154: \end{bwslide}
155:
156:
157: % \begin{bwslide}
158: %\ctitle {TOKENS}
159: %
160: %\begin{nrtc}
161: %\item MANY APPLICATION EXCHANGES ARE ACTUALLY HALF-DUPLEX
162: %\item ``TOKENS'' KEEP TRACK OF WHO MAY SEND DATA
163: %\item REQUESTS FOR A TOKEN CARRY A PRIORITY
164: %\end{nrtc}
165: %\end{bwslide}
166:
167:
168: % \begin{bwslide}
169: %\ctitle {TOKENS}
170: %
171: %\begin{nrtc}
172: %\item CONTROL EXCLUSIVE ACCESS TO PARTICULAR SERVICE
173: %\item TRAFFIC SIGNAL OF SESSION COMMUNICATIONS
174: %\item TOKENS ARE ONE OF:
175: % \begin{nrtc}
176: % \item AVAILABLE \& OWNED
177: % \item AVAILABLE \& NOT OWNED
178: % \item UNAVAILABLE
179: % \end{nrtc}
180: %\item EXCHANGED BETWEEN PEERS
181: %\item MAINTAINED BY SS-PROVIDER
182: %\end{nrtc}
183: %\end{bwslide}
184:
185:
186: % \begin{bwslide}
187: %\ctitle {TOKENS (cont.)}
188: %
189: %\begin{nrtc}
190: %\item 4 TYPES OF TOKENS
191: % \begin{nrtc}
192: % \item DATA, SYNC MINOR, MAJOR/ACTIVITY, RELEASE
193: % \end{nrtc}
194: %\item PERMITTED OPERATIONS
195: % \begin{nrtc}
196: % \item GIVE TOKENS, PLEASE TOKENS, GIVE CONTROL
197: % \end{nrtc}
198: %\end{nrtc}
199: %\end{bwslide}
200:
201:
202: % \begin{bwslide}
203: %\ctitle {CHECKPOINTING}
204: %
205: %\begin{nrtc}
206: %\item MANY APPLICATIONS EXCHANGE LARGE AMOUNTS OF DATA
207: %\item CHECKPOINTS MAY BE INSERTED IN THE DATA STREAM, SO THAT
208: % \begin{nrtc}
209: % \item IF THE TRANSPORT CONNECTION BREAKS AND IS RE-ESTABLISHED,
210: % DATA EXCHANGE MAY RESUME AT THE LAST CONFIRMED CHECKPOINT
211: % \end{nrtc}
212: %\item SEMANTICS PROVIDED BY SS-USER
213: %\item THREE KINDS OF SYNCHRONIZATION
214: % \begin{nrtc}
215: % \item MINOR CHECKPOINTS (NEED NOT BE CONFIRMED)
216: % \item MAJOR CHECKPOINTS
217: % \item RESYNCHRONIZATION
218: % \end{nrtc}
219: %\end{nrtc}
220: %\end{bwslide}
221:
222:
223: % \begin{note}
224: %diagram sync example using ftam
225: %\end{note}
226:
227:
228: % \begin{bwslide}
229: %\ctitle {RESYNC}
230: %
231: %\begin{nrtc}
232: %\item INITIATED BY EITHER SS-USER
233: %\item SETS SESSION TO DEFINED STATE
234: %\item 3 OPTIONS
235: % \begin{nrtc}
236: % \item ABANDON
237: % \item RESTART
238: % \item SET
239: % \end{nrtc}
240: %\item PERMITTED OPERATIONS
241: % \begin{nrtc}
242: % \item RESYNC ACK
243: % \end{nrtc}
244: %\end{nrtc}
245: %\end{bwslide}
246:
247:
248: \begin{bwslide}
249: \ctitle {RESYNCHRONIZATION EXAMPLE}
250:
251: \vskip.5in
252: \diagram[p]{figureA-33}
253: \end{bwslide}
254:
255:
256: % \begin{bwslide}
257: %\ctitle {ACTIVITIES}
258: %
259: %\begin{nrtc}
260: %\item MANY APPLICATION EXCHANGES CONSIST OF SEVERAL SMALLER EXCHANGES
261: %\item LOGICALLY DIFFERENT TASKS
262: % \begin{nrtc}
263: % \item ACTIVITIES CAN BE INTERRUPTED OR DISCARDED
264: % \item DIALOGS WITHIN AN ACTIVITY DISTINGUISH PARTS OF ``TASK''
265: % \end{nrtc}
266: %\end{nrtc}
267: %\end{bwslide}
268:
269:
270: % \begin{bwslide}
271: %\ctitle {ACTIVITIES (cont.)}
272: %
273: %\begin{nrtc}
274: %\item TRANSFER OF LOGICALLY RELATED DATA
275: %\item SEVERAL CONSECUTIVE ACTIVITIES ALLOWED
276: %\item OPERATIONS
277: % \begin{nrtc}
278: % \item START, END, INTERRUPT, RESUME, DISCARD
279: % \end{nrtc}
280: %\item SEMANTICS PROVIDED BY SS-USER
281: %\end{nrtc}
282: %\end{bwslide}
283:
284:
285: % \begin{note}
286: %diagram activities example
287: %\end{note}
288:
289:
290: % \begin{bwslide}
291: %\ctitle {ACTIVITIES (cont.)}
292: %
293: %\begin{nrtc}
294: %\item IMPLEMENTATION CONCERNS
295: % \begin{nrtc}
296: % \item INTERRUPT/RESUME = SAVE/RESTORE STATE
297: % \item BURDEN ON SS-USER
298: % \end{nrtc}
299: %\end{nrtc}
300: %\end{bwslide}
301:
302:
303: % \begin{bwslide}
304: %\ctitle {EXCEPTIONS}
305: %
306: %\begin{nrtc}
307: %\item SOME APPLICATIONS MAY EXPERIENCE ABNORMAL EVENTS REQUIRING DRASTIC ACTION
308: %\item AN EXCEPTION CAN BE REPORTED INSTEAD OF ABORTING THE CONNECTION
309: %\item THE CONNECTION MUST BE BROUGHT TO A KNOWN STATE TO CLEAR AN EXCEPTION AND
310: % REQUIRES EXPLICIT ACTION ON THE OTHER SIDE
311: %\end{nrtc}
312: %\end{bwslide}
313:
314:
315: % \begin{bwslide}
316: %\ctitle {SESSION QUALITY OF SERVICE (QOS)}
317: %
318: %\begin{nrtc}
319: %\item MOST PARAMETERS PASSED TO TRANSPORT SERVICE
320: %\item OF CONCERN TO SESSION ENTITY:
321: % \begin{nrtc}
322: % \item BATCH SEVERAL PRIMITIVES FOR SENDING
323: % \item ALLOW FLOW--CONTROL BYPASS
324: % \end{nrtc}
325: %\end{nrtc}
326: %\end{bwslide}
327:
328:
329: % \begin{bwslide}
330: %\ctitle {SESSION QUALITY OF SERVICE (cont.)}
331: %
332: %\begin{nrtc}
333: %\item RULES FOR NEGOTIATION
334: %\item NOT REFLECTED IN PROTOCOL!
335: %\end{nrtc}
336: %\end{bwslide}
337:
338:
339: % \begin{bwslide}
340: %\ctitle {TRANSPORT FUNCTIONALITY}
341: %\end{bwslide}
342:
343:
344: % \begin{bwslide}
345: %\ctitle {CONNECTION ESTABLISHMENT}
346: %
347: %\begin{nrtc}
348: %\item NEGOTIATES
349: % \begin{nrtc}
350: % \item FUNCTIONAL UNITS
351: % \item INITIAL TOKEN POSITIONS
352: % \item MAXIMUM TSDU SIZE
353: % \item OPTIONS/VERSION/...
354: % \end{nrtc}
355: %\item TWO WAY EXCHANGE
356: %\item LITTLE ADDED FUNCTIONALITY OVER TRANSPORT, {\bf BUT A LOT MORE WORK!}
357: %\end{nrtc}
358: %\end{bwslide}
359:
360:
361: % \begin{bwslide}
362: %\ctitle {CONNECTION RELEASE}
363: %\end{bwslide}
364:
365:
366: % \begin{bwslide}
367: %\ctitle {DATA TRANSFER\\SESSION USER DATA}
368: %
369: %\begin{nrtc}
370: %\item SESSION SERVICE DATA UNIT (SSDU)
371: %\item COMPOSED OF OCTETS (1 OR MORE)
372: %\item PASS OPAQUELY THROUGH SESSION SERVICE
373: %\item 3 TYPES OF SSDUs, WE WILL JUST CALL THEM SSDUs
374: %\end{nrtc}
375: %\end{bwslide}
376:
377:
378: \begin{bwslide}
379: \ctitle {SESSION USER DATA (cont.)}
380:
381: \begin{nrtc}
382: \item ORIGINAL RESTRICTIONS ON SSDU SIZE FOR CONNECTION ESTABLISHMENT
383: \begin{nrtc}
384: \item LIMIT OF 512 OCTETS
385: \item SESSION VERSION 1
386: \end{nrtc}
387: \item TOO RESTRICTIVE FOR MANY OSI APPLICATIONS
388: \begin{nrtc}
389: \item e.g., PASSING OSI DIRECTORY NAMES ON CONNECTIONS
390: \end{nrtc}
391: \item RECENT ADDENDA REMOVE THIS LIMIT
392: \begin{nrtc}
393: \item PRACTICAL LIMIT OF 10K OCTETS USED
394: \item SESSION VERSION 2
395: \end{nrtc}
396: \item VERSION 1 \& 2 DO \underline{NOT} INTERWORK
397: \begin{nrtc}
398: \item NO NEGOTIATION POSSIBLE
399: \item VERSION 2 MAY DOWNGRADE TO VERSION 1
400: \end{nrtc}
401: \end{nrtc}
402: \end{bwslide}
403:
404:
405:
406:
407: % \begin{bwslide}
408: %\ctitle{DATA UNITS}
409: %
410: %\begin{nrtc}
411: %\item SSDU --- PASSED BETWEEN SS-USERS
412: %\item SPDU --- PASSED BETWEEN SS-PROVIDERS
413: %\end{nrtc}
414: %\end{bwslide}
415:
416:
417: % \begin{bwslide}
418: %\ctitle {SPDU STRUCTURE}
419: %
420: %\begin{nrtc}
421: %\item 4 COMPONENTS
422: %\item USER DATA vs. USER INFORMATION
423: %\item USER INFORMATION PRESENT ONLY ON NORMAL \& TYPED DATA SPDUs
424: %\end{nrtc}
425: %\end{bwslide}
426:
427:
428: % \begin{note}
429: %diagram spdu structure
430: %\end{note}
431:
432:
433: % \begin{bwslide}
434: %\ctitle {SESSION FUNCTIONAL UNITS}
435: %
436: %\begin{tabular}{ll}
437: %KERNEL & CAPABILITY DATA \\
438: %NEGOTIATED RELEASE & MINOR SYNC \\
439: %DUPLEX & MAJOR SYNC \\
440: %HALF DUPLEX & RESYNC \\
441: %EXPEDITED DATA & ACTIVITY \\
442: %TYPED DATA & EXCEPTIONS \\
443: %\end{tabular}
444: %\end{bwslide}
445:
446:
447: % \begin{bwslide}
448: %\ctitle {FUNCTIONAL UNIT SUBSETS}
449: %
450: %\begin{nrtc}
451: %\item FOR SOME TIME ``POPULAR'' FUNCTIONAL UNIT SUBSETS WERE DEFINED:
452: % \begin{nrtc}
453: % \item BCS --- BASIC COMBINED SUBSET
454: % \item BSS --- BASIC SYNCHRONIZATION SUBSET
455: % \item BAS --- BASIC ACTIVITY SUBSET
456: % \end{nrtc}
457: %\item NO LONGER USED, REFERENCE INDIVIDUAL FUNCTIONAL UNITS
458: %\end{nrtc}
459: %\end{bwslide}
460:
461:
462: \begin{bwslide}
463: \ctitle {IMPLEMENTATION CONSIDERATIONS}
464:
465: \begin{nrtc}
466: \item SIMILAR TO OTHER UPPER LAYERS
467: \item WHERE
468: \begin{nrtc}
469: \item USER LIBRARY
470: \item DISTINCT PROCESS
471: \item KERNEL RESIDENT
472: \end{nrtc}
473: \end{nrtc}
474: \end{bwslide}
475:
476:
477: % \begin{bwslide}
478: %\ctitle {SESSION VERSION 2}
479: %
480: %\begin{nrtc}
481: %\item ``UNLIMITED'' USER DATA ON CONNECT
482: % \begin{nrtc}
483: % \item STANDARDS LIMIT IS 64K OCTETS IN SINGLE SPDU
484: % \item PRACTICAL LIMIT IS 10K OCTETS ON CONNECTION ESTABLISHMENT
485: % \end{nrtc}
486: %\end{nrtc}
487: %\end{bwslide}
488:
489:
490: % \begin{bwslide}
491: %\ctitle {SESSION}
492: %
493: %\center{\huge ``The sewer of OSI''}
494: %\end{bwslide}
495:
496:
497: % \begin{bwslide}
498: %\ctitle {REFERENCES}
499: %
500: %\begin{description}
501: %\item[ISO/IEC 8326:] Basic Connection Oriented Session Service Definition
502: %\item[ISO/IEC 8327:] Basic Connection Oriented Session Protocol Specification
503: %\end{description}
504: %\end{bwslide}
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