documentation/specification/protocols.txt

i-scream Protocols
==================

Contents
--------
 - Conventions

 - Host Connection Protocol
 - Host Heartbeat Protocol
 - Host Data Protocol

 - Client Control Protocol
 - Client Data Protocol


Conventions
-----------
All protocols in this document assume a valid connection of
the appropriate type has been made, and that data streams
are already available.  All strings should, and will be,
terminated with a \n (newline character) to indicate the end
of the message.  All messages are sent as ASCII Strings.

Fixed protocol messages will appear in [] brackets, if there
is a variety of options they will be separated with the |
character.  For example:

    [OK|ERROR]
   
Indicates that the message "OK" OR the message "ERROR" will
be sent depending on the result of the last action.

Data messages will appear in {} brackets, where the name in
the brackets indicates the type (as in kind, not data type)
of data that will be returned.  For example:

    {lastmodified}

Indicates that data for use as 'last modified' will be 
returned.   

If [ERROR] is sent back at any time, this indicates that all 
communication is over. EXCEPT where otherwise specified!


Host Connection Protocol
------------------------
The initial connection of a host to the i-scream server is
through the FilterManager.  A Host gets its configuration
and then gets assigned a Filter to connect to and start
sending data.

The port number of the FilterManager is fully configurable,
however the default at this time is 4567.

Host         (direction) Server         Comment
------------------------------------------------------------
[STARTCONFIG]---------->                Requests to start
                                        receiving config
                                        information
            
             <---------- [OK|ERROR]     If the server ok's
                                        the request or not

[LASTMODIFIED]---------->               Asks when the config
                                        was last modified
                                        (used when checking
                                        if the config has
                                        changed)
            
             <---------- [{lastmodified}Returns a long int
                         |ERROR]        time since epoch
                                        eg, 123456789

[FILELIST]   ---------->                Asks the server for
                                        the list of files
                                        that were used to
                                        build the config
                                        (used when checking
                                        if the config has
                                        changed)
       
             <---------- [{filelist}    Returns a semi-colon
                         |ERROR]        separated list of
                                        filenames
                                        eg,
                                        a.conf;b.conf;c.conf

             ********** LOOP START **********
             This loop reads configuration
             properties from the config

[{property}] ---------->                Sends the name of a
                                        property to be
                                        retrieved from the
                                        config file
                                        eg, UDPUpdateTime
            
             <---------- [{value}|ERROR]Returns the value of
                                        the requested config
                                        property
                                        eg, 120
                                        If it is unable to
                                        find the requested
                                        property it returns
                                        ERROR to indicate
                                        that fact, but 
                                        communication still 
                                        proceeds
                                       
             ********** LOOP UNTIL **********
             The loop continues until the host
             sends the following message
            
[ENDCONFIG]  ---------->                Indicates that the
                                        host requires no
                                        more config
            
             ********** LOOP  END **********
             Communication continues
            
             <---------- [OK]           Indicates that the
                                        server is ready to
                                        proceed
                                       
[FILTER]     ---------->                Asks the server to
                                        send it the host
                                        information of a
                                        filter that it
                                        should connect to
                                       
             <---------- {filter}       Returns a semi-colon
                                        separated list of
                                        FQDN hostname, UDP
                                        port number and TCP
                                        port number that a
                                        configured Filter is
                                        running on and
                                        assigned to the
                                        calling host
                                        eg,
                                        raptor.ukc.ac.uk;
                                        1234;5678

[END]        ---------->                Indicates to the
                                        server that the host
                                        has finished an will
                                        disconnect
            
             <---------- [OK|ERROR]     Indicates that the
                                        server is either ok
                                        or that it thought
                                        there was an error
<<<<<<< protocols.txt
------------------------------------------------------------

=======
       
>>>>>>> 1.2
Host Heartbeat Protocol
-----------------------
When a host is configured after it has connected it should
obtain a property TCPUpdateTime.  This indicates how often
a host should send a "Heart Beat", which is a pro-active
connection to the server by the host to indicate that it is
still alive.  This "Heart Beat" also allows a host to see
its configuration has changed and act accordingly.  In a
well written host this should just be a case of dropping out
of a loop and heading back to the start (connecting to the
filter manager).

Host            (direction) Server      Comment
------------------------------------------------------------
[HEARTBEAT]     ---------->             Starts the
                                        heartbeat protocol
                                        off
                                       
                <---------- [OK|ERROR]  Indicates that the
                                        server is ok or not

[CONFIG]        ---------->             Indicates that the
                                        host wants to check
                                        its config

                <---------- [OK|ERROR]  Indicates that the
                                        server is ok or not

[{filelist}]    ---------->             Send a semi-colon
                                        separated list of
                                        filenames
                                        eg,
                                        a.conf;b.conf;c.conf
                                        This should be
                                        identical to the one
                                        received in the
                                        connection protocol

                <---------- [OK]        Indicates that the
                                        server is ok

[{lastmodified}]---------->             Returns a long int
                                        time since epoch
                                        eg, 123456789
                                        This should be
                                        identical to the one
                                        received in the
                                        connection protocol

                <---------- [OK|ERROR]  The server then
                                        checks all the files
                                        in the file list to
                                        see if they have
                                        been modified more
                                        recently than the
                                        lastmodified value.
                                        If they HAVE that
                                        indicates that the
                                        configuration has
                                        changed and the host
                                        should re-configure,
                                        thus it sends ERROR.
                                        If the files remain
                                        unchanged the server
                                        will return OK to
                                        indicate the host
                                        should continue as
                                        before

[ENDHEARTBEAT]  ---------->             Indicates to the
                                        server that the host
                                        has finished an will
                                        disconnect
               
                <---------- [OK|ERROR]  Indicates that the
                                        server is either ok
                                        or that it thought
                                        there was an error
------------------------------------------------------------

Host Data Protocol
------------------
The UDP data packets that are sent by the host contain
simply XML data.  For information on the format of this
data see the XML via UDP specification document at:

http://www.i-scream.org.uk/cgi-bin/docs.cgi?doc=specificatio
n/xml_via_udp.txt

Client Control Protocol
-----------------------

The client control protocol channel is opened by the client
and allows a variety of actions to be carried out by the
client at anytime.  Unlike previous protocols, this is NOT
sequential, all of the requests can be carried out in 
any order.

All client protocols are backwards compatible, and the
version is shown by the protocol identifier.

There are three sections to this protocol.

1) Initialise (sent only at start)
2) Send command(s) - unlimited number in any order
3) Disconnect (sent only at end)

If at anytime the client sends something the server does
not understand, an [ERROR] will be sent

All are indicated with <> brackets.

v1.0 - Protocol identifier: "PROTOCOL 1.0" (without quotes)
       Supported commands:
            STARTCONFIG
            STARTDATA
            STOPDATA

Host         (direction) Server         Comment
------------------------------------------------------------
<initialise>
[CONNECT]    ---------->                Starts off the 
                                        client protocol
             
             <---------- [{protocol}]   The server sends the
                                        protocol identifier
                                        
[{name}]     ---------->                The client sends its
                                        "name".  This name
                                        is used to identify
                                        the type of client
                                        to the system and
                                        obtain its config
                                        eg, Conient
             
             <---------- [OK]           Indicates the server
                                        is ok to proceed
                        

<command #1> (allows client to obtain its configuration)
[STARTCONFIG]---------->                Tell the server we
                                        want to start this
                                        command
             
             <---------- [OK]           Indicates the server
                                        is ok to proceed
             
             ********** LOOP START **********
             This loop reads configuration
             properties from the config

[{property}] ---------->                Sends the name of a
                                        property to be
                                        retrieved from the
                                        config file
                                        Clients can obtain
                                        host information
                                        eg, 
                                        Host.UDPUpdateTime
                                        Otherwise it must
                                        prefix requests
                                        with "Client."
                                        All other requests
                                        will be ignored as
                                        if it was unable to
                                        retieve the property
                                        
             <---------- [{value}|ERROR]Returns the value of
                                        the requested config
                                        property
                                        eg, 120
                                        If it is unable to
                                        find the requested 
                                        property it returns
                                        ERROR to indicate
                                        that fact
                                        
             ********** LOOP UNTIL **********
             The loop continues until the client
             sends the following message
             
[ENDCONFIG]  ---------->                Indicates that the 
                                        client requires no
                                        more config
             
             ********** LOOP  END **********
             Communication continues
             
             <---------- [OK]           Indicates that the
                                        server is ready to
                                        proceed

<command #2> (tells the server to start the data link)
[STARTDATA]  ---------->                Tell the server we
                                        want to start this
                                        command
            
             <---------- [{portnumber}  The server then sets
                         |ERROR]        itself listening for
                                        a connection on its
                                        data link socket for
                                        this client.  It
                                        returns the port no.
                                        that it is listening
                                        on eg, 12367
                                        If the data link is
                                        yet to be started
                                        the server will
                                        return ERROR
             
             <---------- [OK]           Indicates the server
                                        is ok to proceed and
                                        the client can 
                                        then connect its
                                        data link

<command #3> (tells the server to stop the data link)
[STOPDATA]   ---------->                Tell the server we
                                        want to start this
                                        command
                                        The server then
                                        shuts down the 
                                        data link to the
                                        client

             <---------- [OK|ERROR]     Returns OK is the
                                        server is ready to
                                        proceed, or ERROR
                                        if the data link
                                        was not open in the
                                        first place

<disconnect>
[DISCONNECT] ---------->                Tells the server the
                                        client wants to
                                        close the control
                                        link
                                        
             <---------- [OK]           The last word from
                                        the server, it will
                                        disappear after this
------------------------------------------------------------

v1.1 - Protocol identifier: "PROTOCOL 1.1" (without quotes)
       Supported commands:
            SETHOSTLIST

Host         (direction) Server         Comment
------------------------------------------------------------
<command #4> (indicates to the server which hosts the client
              wants data from)
[SETHOSTLIST]---------->                Tell the server we
                                        want to start this
                                        command
             
             <---------- [OK|ERROR]     The server will
                                        return an ERROR if
                                        the data link is
                                        open, as a host list
                                        must ONLY be set 
                                        if the data link is
                                        closed
                                        If the server is
                                        ok to proceed with
                                        the command it says
                                        [OK]

[{hostlist}] ---------->                This is a semi-colon
                                        seperated list of
                                        FQDN hostnames that
                                        the client wishes to
                                        recieve data from
                                        eg,
        raptor.ukc.ac.uk;killigrew.ukc.ac.uk;chalk.ukc.ac.uk
                                        
                                        If the list is sent
                                        blank (or if no list
                                        is set at all) then
                                        data from ALL hosts
                                        will be sent to the
                                        client
                                        
             <---------- [OK]           Indicates the server
                                        is ok to proceed and
                                        the host list has 
                                        been accepted
------------------------------------------------------------

Client Data Protocol
--------------------
Once the data link has been opened by the control link, the
server will send XML formated data packets seperated by the 
\n (newline) character.  For information on the format of 
this data see the XML via UDP specification document at:

http://www.i-scream.org.uk/cgi-bin/docs.cgi?doc=specificatio
n/xml_via_udp.txt

About
-----
This document was written by AJ Moore [ajm4@ukc.ac.uk] for
use by the team working on a 3rd year Computer Science
project called "i-scream". More details can be found on the
project website;

http://www.i-scream.org.uk
Revision:	1.3
Committed:	Sun Jan 28 20:05:35 2001 UTC (23 years, 10 months ago) by ajm
Content type:	text/plain
Branch:	MAIN
Changes since 1.2:	+207 -2 lines
Log Message:	added details of client protocol
#	Content
1	i-scream Protocols
2	==================
3
4	Contents
5	--------
6	- Conventions
7
8	- Host Connection Protocol
9	- Host Heartbeat Protocol
10	- Host Data Protocol
11
12	- Client Control Protocol
13	- Client Data Protocol
14
15
16	Conventions
17	-----------
18	All protocols in this document assume a valid connection of
19	the appropriate type has been made, and that data streams
20	are already available. All strings should, and will be,
21	terminated with a \n (newline character) to indicate the end
22	of the message. All messages are sent as ASCII Strings.
23
24	Fixed protocol messages will appear in [] brackets, if there
25	is a variety of options they will be separated with the \|
26	character. For example:
27
28	[OK\|ERROR]
29
30	Indicates that the message "OK" OR the message "ERROR" will
31	be sent depending on the result of the last action.
32
33	Data messages will appear in {} brackets, where the name in
34	the brackets indicates the type (as in kind, not data type)
35	of data that will be returned. For example:
36
37	{lastmodified}
38
39	Indicates that data for use as 'last modified' will be
40	returned.
41
42	If [ERROR] is sent back at any time, this indicates that all
43	communication is over. EXCEPT where otherwise specified!
44
45
46	Host Connection Protocol
47	------------------------
48	The initial connection of a host to the i-scream server is
49	through the FilterManager. A Host gets its configuration
50	and then gets assigned a Filter to connect to and start
51	sending data.
52
53	The port number of the FilterManager is fully configurable,
54	however the default at this time is 4567.
55
56	Host (direction) Server Comment
57	------------------------------------------------------------
58	[STARTCONFIG]----------> Requests to start
59	receiving config
60	information
61
62	<---------- [OK\|ERROR] If the server ok's
63	the request or not
64
65	[LASTMODIFIED]----------> Asks when the config
66	was last modified
67	(used when checking
68	if the config has
69	changed)
70
71	<---------- [{lastmodified}Returns a long int
72	\|ERROR] time since epoch
73	eg, 123456789
74
75	[FILELIST] ----------> Asks the server for
76	the list of files
77	that were used to
78	build the config
79	(used when checking
80	if the config has
81	changed)
82
83	<---------- [{filelist} Returns a semi-colon
84	\|ERROR] separated list of
85	filenames
86	eg,
87	a.conf;b.conf;c.conf
88
89	******** LOOP START ********
90	This loop reads configuration
91	properties from the config
92
93	[{property}] ----------> Sends the name of a
94	property to be
95	retrieved from the
96	config file
97	eg, UDPUpdateTime
98
99	<---------- [{value}\|ERROR]Returns the value of
100	the requested config
101	property
102	eg, 120
103	If it is unable to
104	find the requested
105	property it returns
106	ERROR to indicate
107	that fact, but
108	communication still
109	proceeds
110
111	******** LOOP UNTIL ********
112	The loop continues until the host
113	sends the following message
114
115	[ENDCONFIG] ----------> Indicates that the
116	host requires no
117	more config
118
119	******** LOOP END ********
120	Communication continues
121
122	<---------- [OK] Indicates that the
123	server is ready to
124	proceed
125
126	[FILTER] ----------> Asks the server to
127	send it the host
128	information of a
129	filter that it
130	should connect to
131
132	<---------- {filter} Returns a semi-colon
133	separated list of
134	FQDN hostname, UDP
135	port number and TCP
136	port number that a
137	configured Filter is
138	running on and
139	assigned to the
140	calling host
141	eg,
142	raptor.ukc.ac.uk;
143	1234;5678
144
145	[END] ----------> Indicates to the
146	server that the host
147	has finished an will
148	disconnect
149
150	<---------- [OK\|ERROR] Indicates that the
151	server is either ok
152	or that it thought
153	there was an error
154	<<<<<<< protocols.txt
155	------------------------------------------------------------
156
157	=======
158
159	>>>>>>> 1.2
160	Host Heartbeat Protocol
161	-----------------------
162	When a host is configured after it has connected it should
163	obtain a property TCPUpdateTime. This indicates how often
164	a host should send a "Heart Beat", which is a pro-active
165	connection to the server by the host to indicate that it is
166	still alive. This "Heart Beat" also allows a host to see
167	its configuration has changed and act accordingly. In a
168	well written host this should just be a case of dropping out
169	of a loop and heading back to the start (connecting to the
170	filter manager).
171
172	Host (direction) Server Comment
173	------------------------------------------------------------
174	[HEARTBEAT] ----------> Starts the
175	heartbeat protocol
176	off
177
178	<---------- [OK\|ERROR] Indicates that the
179	server is ok or not
180
181	[CONFIG] ----------> Indicates that the
182	host wants to check
183	its config
184
185	<---------- [OK\|ERROR] Indicates that the
186	server is ok or not
187
188	[{filelist}] ----------> Send a semi-colon
189	separated list of
190	filenames
191	eg,
192	a.conf;b.conf;c.conf
193	This should be
194	identical to the one
195	received in the
196	connection protocol
197
198	<---------- [OK] Indicates that the
199	server is ok
200
201	[{lastmodified}]----------> Returns a long int
202	time since epoch
203	eg, 123456789
204	This should be
205	identical to the one
206	received in the
207	connection protocol
208
209	<---------- [OK\|ERROR] The server then
210	checks all the files
211	in the file list to
212	see if they have
213	been modified more
214	recently than the
215	lastmodified value.
216	If they HAVE that
217	indicates that the
218	configuration has
219	changed and the host
220	should re-configure,
221	thus it sends ERROR.
222	If the files remain
223	unchanged the server
224	will return OK to
225	indicate the host
226	should continue as
227	before
228
229	[ENDHEARTBEAT] ----------> Indicates to the
230	server that the host
231	has finished an will
232	disconnect
233
234	<---------- [OK\|ERROR] Indicates that the
235	server is either ok
236	or that it thought
237	there was an error
238	------------------------------------------------------------
239
240	Host Data Protocol
241	------------------
242	The UDP data packets that are sent by the host contain
243	simply XML data. For information on the format of this
244	data see the XML via UDP specification document at:
245
246	http://www.i-scream.org.uk/cgi-bin/docs.cgi?doc=specificatio
247	n/xml_via_udp.txt
248
249	Client Control Protocol
250	-----------------------
251
252	The client control protocol channel is opened by the client
253	and allows a variety of actions to be carried out by the
254	client at anytime. Unlike previous protocols, this is NOT
255	sequential, all of the requests can be carried out in
256	any order.
257
258	All client protocols are backwards compatible, and the
259	version is shown by the protocol identifier.
260
261	There are three sections to this protocol.
262
263	1) Initialise (sent only at start)
264	2) Send command(s) - unlimited number in any order
265	3) Disconnect (sent only at end)
266
267	If at anytime the client sends something the server does
268	not understand, an [ERROR] will be sent
269
270	All are indicated with <> brackets.
271
272	v1.0 - Protocol identifier: "PROTOCOL 1.0" (without quotes)
273	Supported commands:
274	STARTCONFIG
275	STARTDATA
276	STOPDATA
277
278	Host (direction) Server Comment
279	------------------------------------------------------------
280	<initialise>
281	[CONNECT] ----------> Starts off the
282	client protocol
283
284	<---------- [{protocol}] The server sends the
285	protocol identifier
286
287	[{name}] ----------> The client sends its
288	"name". This name
289	is used to identify
290	the type of client
291	to the system and
292	obtain its config
293	eg, Conient
294
295	<---------- [OK] Indicates the server
296	is ok to proceed
297
298
299	<command #1> (allows client to obtain its configuration)
300	[STARTCONFIG]----------> Tell the server we
301	want to start this
302	command
303
304	<---------- [OK] Indicates the server
305	is ok to proceed
306
307	******** LOOP START ********
308	This loop reads configuration
309	properties from the config
310
311	[{property}] ----------> Sends the name of a
312	property to be
313	retrieved from the
314	config file
315	Clients can obtain
316	host information
317	eg,
318	Host.UDPUpdateTime
319	Otherwise it must
320	prefix requests
321	with "Client."
322	All other requests
323	will be ignored as
324	if it was unable to
325	retieve the property
326
327	<---------- [{value}\|ERROR]Returns the value of
328	the requested config
329	property
330	eg, 120
331	If it is unable to
332	find the requested
333	property it returns
334	ERROR to indicate
335	that fact
336
337	******** LOOP UNTIL ********
338	The loop continues until the client
339	sends the following message
340
341	[ENDCONFIG] ----------> Indicates that the
342	client requires no
343	more config
344
345	******** LOOP END ********
346	Communication continues
347
348	<---------- [OK] Indicates that the
349	server is ready to
350	proceed
351
352	<command #2> (tells the server to start the data link)
353	[STARTDATA] ----------> Tell the server we
354	want to start this
355	command
356
357	<---------- [{portnumber} The server then sets
358	\|ERROR] itself listening for
359	a connection on its
360	data link socket for
361	this client. It
362	returns the port no.
363	that it is listening
364	on eg, 12367
365	If the data link is
366	yet to be started
367	the server will
368	return ERROR
369
370	<---------- [OK] Indicates the server
371	is ok to proceed and
372	the client can
373	then connect its
374	data link
375
376	<command #3> (tells the server to stop the data link)
377	[STOPDATA] ----------> Tell the server we
378	want to start this
379	command
380	The server then
381	shuts down the
382	data link to the
383	client
384
385	<---------- [OK\|ERROR] Returns OK is the
386	server is ready to
387	proceed, or ERROR
388	if the data link
389	was not open in the
390	first place
391
392	<disconnect>
393	[DISCONNECT] ----------> Tells the server the
394	client wants to
395	close the control
396	link
397
398	<---------- [OK] The last word from
399	the server, it will
400	disappear after this
401	------------------------------------------------------------
402
403	v1.1 - Protocol identifier: "PROTOCOL 1.1" (without quotes)
404	Supported commands:
405	SETHOSTLIST
406
407	Host (direction) Server Comment
408	------------------------------------------------------------
409	<command #4> (indicates to the server which hosts the client
410	wants data from)
411	[SETHOSTLIST]----------> Tell the server we
412	want to start this
413	command
414
415	<---------- [OK\|ERROR] The server will
416	return an ERROR if
417	the data link is
418	open, as a host list
419	must ONLY be set
420	if the data link is
421	closed
422	If the server is
423	ok to proceed with
424	the command it says
425	[OK]
426
427	[{hostlist}] ----------> This is a semi-colon
428	seperated list of
429	FQDN hostnames that
430	the client wishes to
431	recieve data from
432	eg,
433	raptor.ukc.ac.uk;killigrew.ukc.ac.uk;chalk.ukc.ac.uk
434
435	If the list is sent
436	blank (or if no list
437	is set at all) then
438	data from ALL hosts
439	will be sent to the
440	client
441
442	<---------- [OK] Indicates the server
443	is ok to proceed and
444	the host list has
445	been accepted
446	------------------------------------------------------------
447
448	Client Data Protocol
449	--------------------
450	Once the data link has been opened by the control link, the
451	server will send XML formated data packets seperated by the
452	\n (newline) character. For information on the format of
453	this data see the XML via UDP specification document at:
454
455	http://www.i-scream.org.uk/cgi-bin/docs.cgi?doc=specificatio
456	n/xml_via_udp.txt
457
458	About
459	-----
460	This document was written by AJ Moore [ajm4@ukc.ac.uk] for
461	use by the team working on a 3rd year Computer Science
462	project called "i-scream". More details can be found on the
463	project website;
464
465	http://www.i-scream.org.uk