Re: Banana Republic (was Re: OpenVMS Book Wins award)
- From: Mark Daniel <mark.daniel@xxxxxxxxxx>
- Date: Sun, 16 Nov 2008 18:08:27 +1030
Richard Maher wrote:
Hi Mark,
Thanks for the reply. (Sorry for the delay)
I noted the post on Adobe policy files.
I think the HTML5 people ignore policy-files at their peril. (Not that they
seem to care as their world is all HTTP-shaped with no end of lovely
"headers")
Cross-domain access is one of the holy grails of distributed applications (at least those that can be mashed together from existing webby technologies) and are always fraught with security related issues.
Of course there probably also is an element of 'HTML people' tending to have only a hammer in their toolbox (no real slight intended).
[Orbited] Without some sort of access
control it functions as an open relay - carte blanche.
I haven't used it but I believe they have some sort of white-list.
That is coarse-grained access control.
Adobe policy files are a structured, finer-grained white-list.
>Both are broad, evolving concepts and implementations.
Unlike TCP/IP and/or UDP Sockets with Java that have been around since year
dot. (Ok, sandboxed or signed up until now)
FYIW; I have an (as-yet) unpublished Web application displaying
elementary graphs of $GETRMI (monitor) data. It uses a Comet-style
<IFRAME> and streaming long-poll. When system data changes it generates
a <script>ed function call into browser JavaScript that supplies data
values which the application JavaScript then graphs or displays. One
buffered I/O of a few tens to a few hundreds of bytes (depending on what
data have changed) per sample period. Negligible CPU ticks. Not
full-duplex but not synchronous-poll either.
Look, polling is anathema to me but when it comes to System Stats or
RMU/SHOW STATS etc, I don't have that much of a problem with it. I mean to
try to fire off an event every time something happens on a system or a
database might generate a bit of a flood. And each users might like to set
their own "sample" (or poll) interval?
Anyway, I understand it's "How your example works" rather than "What it's
doing" that's important. Sounds interesting, I look forward to seeing it.
To better convey that this example has some level of sophistication here is a (short-lived) peek at the HMI
http://wasd.vsm.com.au/wasd_tmp/mondesi_081116a.png
The bar graph is the instantaneous value (at a selected sample period of 2 seconds). The line graph displays the history over the last five minutes. It's all HTML (via DOM) and JavaScript. The graphed 'events' (changes in RMI data) are individually and asynchronously provided from the server to the client over a persistent (long-lived) connection and each respective graphical element is equally asynchronously updated. It's not classic polling as you might generally describe it. Historical data are stored in the browser. I did a couple of compiles to generate a more interesting image.
The application is really just an exercise in Comety stuff and what can be done with dynamic applications in a standard browser (though perhaps with some potential usefulness).
Though, one thing I have been curious about with Comet (and possibly your
example) is what is the server thread/process doing while it's waiting for
(say Stock Price for FMG to change or to move past some limit(s))
It can be doing anything it is capable of; hibernating usually, waiting for some event such as a timer (i.e. sleeping) but of course it could 'register' for any event the implementation environment provides and use that to provide data.
In the above application's case, when it wakes it does a $GETRMI and a $GETSYI, and then IPCs changed data to the client, before hibernating again. CPU hardly 'ticks' at all. One (or none) buffered I/O.
> Is this
thread/process serving *all* clients or is there a 1:1 relationship?
In all general purpose Web serving there is such a relationship. This is definitely the case in the above application which is written as a CGI script. All VMS Web servers would activate an instance for each client (in fact for a CGI script, all servers period). Of course in many Web environments there would be nothing preventing the design and implementation of something (like an Apache module) which maintained a single, internal 'application' that serviced multiple, concurrent clients.
How is
the connection-state and context maintained between the producing-service(s)
and the consuming client?
This is probably a non-question for such an elementary application.
However, in the above case, the browser connects to the server; the server then activates the application and provides IPC from it back to the client browser. The network connection persists as long as maintained by the client and/or server and/or network. If and when the connection is dropped the browser (notified via a DOM event) re-requests data from the server (not requiring a page refresh, this is transparent to the user). State and context are implicit. Data are timestamped by the application, IPCed to the browser, placed in an time-ordered buffer maintained by the browser, which then plots each against the time (X) axis with every new datum. Stale data are removed from the 'older end' of the buffer.
Is the thread/process unavailable for servicing
other requests while it's streaming its long-poll (or words to that effect
:-)
Yes.
If you mean, provide asynchronous (event triggered), binary (non-HTTP)
comms using these ports then yes. Of course there is no reason why the
services requested over these ports cannot further proxy the binary to
TCP anything-configured. IMO the bottom line is (again) access-control.
Whether this is the lone advantage is moot.
But I thought this is what the mail from Shannon of the WHATWG (in my
earlier post) describes as problematic? - I'm confused.
My explanation was a bit thin. What I intended to describe was a Web Socket 'service' (implement it how you like, might be as simple as a script) under control of the origin server that then connected the Web Socket 'request' directly using raw IP socket(s) to whatever the access control allowed. It could also do the necessary data encoding changes between the Web Socket protocol and the raw end-point.
This of course is NOT what you are looking for; direct browser-to-raw-IP-endpoint. However it can (I'm guessing because I obviously haven't tried it) emulate (perhaps 'tunnel' might be better) asynchronous, raw network streams via a Web Socket server / raw IP network proxy. At the risk of becoming (more) repetitive, carte blanche access is game-over.
If Sockets can't traverse public proxy-servers with existing HTTP thenThis one has lost me but I'll have a go at two of the possible intents:
option 1 is no longer on the table as far as I can see?
1) If you mean Web Sockets can't through existing HTTP proxy then the
answer seems to me that they are designed to do just that. Web Sockets
behind proxy servers know it and appropriately CONNECT to tunnel.
I thought that's what Shannon was saying was problematic as they do go
through, but all roads lead to 443?
I did begin that response with a disclaimer
It appears this was prudent ;-)
An interesting and opportune thread, Mark.
Cheers Richard Maher.
"Mark Daniel" <mark.daniel@xxxxxxxxxx> wrote in message
news:0118206d$0$20660$c3e8da3@xxxxxxxxxxxxxxxxxxxx
Richard Maher wrote:beHi Mark,
Thanks for the reply.
I bought it through Barnes and Noble in late May '08 for US$36.00 plus
US$13.00 P&P, and I think my credit card statement said something like
AU$52.00 so it was right at the 'peak'. Why the AU$ currently should
hereat US$0.65 now escapes me - perhaps that's one reason I'm still workingI looked seriously at Perth Mint gold in August (when the bank deposit
for wages.
guarantee was sweet FA) and Foreign Currency accounts aren't as common
Appletsas they are in the UK. Either way I would (and have) lost big time - but
haven't we all :-(
That any network connectivity has some sandboxing doesn't exactlyMe either! I'm a big fan of the same-origin, or codebase, policy for
surprise me.
connectionbut these guys just want to keep pushing the envelope.I noted the post on Adobe policy files.
;-)A network conduit (like SSH or HTTP CONNECT) is carteYeah, but here I bow
blanche for whatever the agent wishes to transfer. No constraint would
be considered negligence.
to your much greater experience and ask "What the hellIsn't a(n IP) socket proxy that doesn't explicitly talk HTTP during
can a *Socket not HTTP* proxy-server do for me?".
setup a one-to-one NAT router? And if accepting external connection
requests, a static port mapping NAT router, into/through the DMZ and
onto internal services? And so forth through the NAT variants.
Look I wanted a HTTP
CONNECT handshake to give me a Tunnel for my Socket over a httpS
(seeto an arbitray TCP/IP server, but it doesn't look doable; please advise.I can but reframe my previous comment; unconstrained connectivity from
browser based applications is surely like signing a full book of blank
cheques.
I also view with interest what the Comet guys are doing with Orbitedbywww.cometdaily.com for some background) as they don't seem to be boundadvantage(or have already solved) these proxy-server restrictions.AIUI; Orbited is a service used to accept Web-style socket connection
requests from browsers, establish Comet-style, bidirectional
communication with the browser, then proxy (or forward, or gateway, or
<whatever-you-feel-comfortable-describing-it-as>) that communication via
a TCP socket to the requested end-point. Without some sort of access
control it functions as an open relay - carte blanche. With access
control it's a lot like most CONNECT proxy, or at least CONNECT
reverse-proxy. Of course it's a bit more than that (but isn't
everything!) Until Web Sockets become commonplace it uses a number of
approaches to *emulate* asynchronous comms with current browsers.
AIUI; Comet is a broad term used to described leveraging HTTP
server-push of unsolicited/unpolled/asynchronous data to the browser,
using existing HTTP technologies, most commonly, though not restricted
to, streaming of a series individual response data 'inside' a persisting
HTTP connection, currently via 'long polling' and XMLhttpRequest() or
<script> tag instances. It's a compromise hack. Not perfect but it
works. Of course it's more than this (but then isn't everything!)
Undoubtably it will(/is) develop(ing) to encompass Web Sockets, etc.
Both are broad, evolving concepts and implementations.
FYIW; I have an (as-yet) unpublished Web application displaying
elementary graphs of $GETRMI (monitor) data. It uses a Comet-style
<IFRAME> and streaming long-poll. When system data changes it generates
a <script>ed function call into browser JavaScript that supplies data
values which the application JavaScript then graphs or displays. One
buffered I/O of a few tens to a few hundreds of bytes (depending on what
data have changed) per sample period. Negligible CPU ticks. Not
full-duplex but not synchronous-poll either.
>I'm guessing you mention this because the suggestion below thatDamn, I'm as transparent and one-domensional as usual :-)
"that the time could be better spent providing guidelines for
communication via an asynchronous CGI [originally I read GUI :-]
interface."
sounds remarkably like Tier3 :-)The way I see it is we have two camps (and I'm happy to live with the
pluralism and think there's enough room for everyone).
1) The WebSockets http/html5 guys who have the distinct (and only)binary,of being able to tunnel out of 80/443 as HTTPIf you mean, provide asynchronous (event triggered), binary (non-HTTP)
comms using these ports then yes. Of course there is no reason why the
services requested over these ports cannot further proxy the binary to
TCP anything-configured. IMO the bottom line is (again) access-control.
Whether this is the lone advantage is moot.
Of course Web Sockets require specialised server (and proxy server) as
well as client (browser) support.
The WASD mudmap includes Web Sockets server support (either 10.0 in
mid-'09, or 10.1 in mid-'10). Perhaps once HTML5 moves from draft :-}
2) The New Order of full-blown, connection-oriented, full-duplex,beSocket InteractionNo doubt this will be remarkably versatile in the absence of sandboxing,
with many-and-varied conduits established between user's browsers and
all manner of 'services'.
If Sockets can't traverse public proxy-servers with existing HTTP thenThis one has lost me but I'll have a go at two of the possible intents:
option 1 is no longer on the table as far as I can see?
1) If you mean Web Sockets can't through existing HTTP proxy then the
answer seems to me that they are designed to do just that. Web Sockets
behind proxy servers know it and appropriately CONNECT to tunnel.
2) If you mean TCP sockets can't then no, unless they speak the
application-level protocol required by the proxy (which would make them
Web Sockets for all intents and purposes :-)
Anyway, please let me ask the question of why anyone would want to use aDifficult to cache without meta-data.
proxy-server for Socket communication?
. Socket Cacheing - No Thanks
. Limited client IP addresses - IPV6Still a ways off. And there's always the private/public address thingy.
. Anonymity - Not always a good thingInternal opacity usually is a good thing.
. Firewall - Open up connections to/from valid hosts/portsAccess control usually is a good thing.
. Monitoring/filtering - Requirements spec for binary dataMany organisations have a legal requirement to audit their activities.
Certainly mine does.
BFN, Mark.
Cheers Richard Maher
"Mark Daniel" <mark.daniel@xxxxxxxxxx> wrote in message
news:011308d4$0$20645$c3e8da3@xxxxxxxxxxxxxxxxxxxx
Richard Maher wrote:Hi Mark,I bought it through Barnes and Noble in late May '08 for US$36.00 plus
(I purchased it when AU$ was almost at US$ parity :-)Aaah, it seems like only weeks ago :-(
US$13.00 P&P, and I think my credit card statement said something like
AU$52.00 so it was right at the 'peak'. Why the AU$ currently should
oneat US$0.65 now escapes me - perhaps that's one reason I'm still working
for wages.
It was a good 'background' read but not directly applicable to my
daytime duty statement these days. I had not (as I indicated to Roland
I might) gotten around to a public review (that would have required a
second read). Willem Grooters provided one I'd generally endorse.
At around the same time I purchased Heller's, "Catch 22" (shipped toisof my daughters), Earl's, "Digital Equipment Corporation (MA) (Images
of America)", and Schein's, "DEC Is Dead, Long Live DEC"; all good
reads and all for different reasons. With the exchange rate more like
2:3 I might have to think think more carefully. (The Earl soft-cover
youa particularly easy but also interesting 'read' I'd recommend to all
interested in DEC :-)
Cheers Richard Maher
PS. Just in case you don't subscribe to the WHATWG mailing list, doanyhaveCONNECTany interest in, or opinions on the following: -No I don't and indirectly I guess I do.
That any network connectivity has some sandboxing doesn't exactly
surprise me. A network conduit (like SSH or HTTP CONNECT) is carte
blanche for whatever the agent wishes to transfer. No constraint would
be considered negligence.
I'm guessing you mention this because the suggestion below that
"that the time could be better spent providing guidelines for
communication via an asynchronous CGI [originally I read GUI :-]
interface."
sounds remarkably like Tier3 :-)
I agree; why would anyone spend time abstracting interfaces if a
monolithic solution is all that is currently required? Of course this
is an entirely fresh (if not novel) discussion point ...
----- Original Message ----- From: "Shannon"
To: "WHAT working group" >
Sent: Tuesday, October 14, 2008 7:22 AM
Subject: [whatwg] WebSocket and proxies
In the process of testing my WebSocket proposal I discovered theanythingmethod has a major restriction. Most proxies disable CONNECT tobut port 443.
The following is from "Squid and the Blowfish":
------------------
It is very important that you stop CONNECT type requests to non-SSL
ports. The CONNECT method allows data transfer in any direction at
byentertime, regardless of the transport protocol used. As a consequence, a
malicious user could telnet(1) to a (very) badly configured proxy,
something like:
... snip example ...
and end up connected to the remote server, as if the connection was
originated by the proxy.
-------------------
I verified that Squid and all public proxies I tried disable CONNECTbedefault to non-SSL ports. It's unlikely many internet hosts will have
443 available for WebSockets if they also run a webserver. It could
alsodone with virtual IPs or dedicated hosts but this imposes complex
requirements and costs over alternatives like CGI.
The availability and capabilities of the OPTIONS and GET protocolstovaried from proxy to proxy. The IETF draft related to TLS
(http://tools.ietf.org/html/draft-ietf-tls-http-upgrade-05) has this
GET.testingsay:-------------------
3.2 Mandatory Upgrade
If an unsecured response would be unacceptable, a client MUST send
an OPTIONS request first to complete the switch to TLS/1.0 (if
possible).
OPTIONS * HTTP/1.1
Host: example.bank.com
Upgrade: TLS/1.0
Connection: Upgrade
-------------------
So according to this draft spec OPTIONS is the only way to do a
*mandatory* upgrade of our connection. Once again this failed in
than-------------------
=> OPTIONS * HTTP/1.1
=> Proxy-Connection: keep-alive
=> Connection: Upgrade
=> Upgrade: WebSocket/1.0
=> Host: warriorhut.org:8000
=>
<= HTTP/1.0 400 Bad Request
<= Server: squid/3.0.STABLE8
--------------------
Other proxies gave different errors or simply returned nothing. The
problem may be related to the Upgrade and Connection headers rather
OPTIONS, since I had similar issues using Connection: Upgrade withheader.I had the most success using GET without a Connection: UpgradedoesIt seems that the proxy thinks the header is directed at it so itfixbenot pass it on to the remote host. In many cases it will abort the
connection. Using the Upgrade: header without Connection allows the
Upgrade header through to the actual websocket service.
It seems to me that whatever we try in many cases the connection willthesilently dropped by the proxy and the reasons will be unclear due tolack of error handling. There seems to be a wide variation in proxy
behaviour for uncommon operations. I suppose proxy developers could
beforethese issues but whether a significant rollout could be achievedreasonsHTML5 is released is questionable.
Given that an asynchronous connection cannot be cached the onlylightsecurityremaining for going through a proxy are anonymity and firewall
traversal. Automatically bypassing the users proxy configuration to
solve the issues above has the potential to break both of these. It
would be a significant breach of trust for a UA to bypass the users
proxy and some networks only allow connections via a proxy (for
and monitoring).
It seems that we're stuck between a rock and hard place here. Inbetterof this I reiterate my earlier suggestion that the time could berelayspent providing guidelines for communication via an asynchronous CGI
interface. This would allow reuse of existing port 80 and 443 web
services which would resolve the cross-domain issues (the CGI can
the actual service via a backend connection) and most of the proxyports).
issues above (since proxy GET and CONNECT are more reliable on these
Shannon"Mark Daniel" <mark.daniel@xxxxxxxxxx> wrote in message
news:01110d0c$0$20616$c3e8da3@xxxxxxxxxxxxxxxxxxxx
yyyc186 wrote:The Minimum You Need to Know About Service Orieted Architecture byCongratulations Roland!
Roland Hughes
Award-Winner in the Business: Technology/Computers/Internet category
of the National Best Books 2008 Awards, sponsored by USA Book News
(I purchased it when AU$ was almost at US$ parity :-)
You can find this book in Island Computer's Web store.
- Follow-Ups:
- Re: Banana Republic (was Re: OpenVMS Book Wins award)
- From: Richard Maher
- Re: Banana Republic (was Re: OpenVMS Book Wins award)
- References:
- Re: Banana Republic (was Re: OpenVMS Book Wins award)
- From: Richard Maher
- Re: Banana Republic (was Re: OpenVMS Book Wins award)
- Prev by Date: Re: OVMS Integrity BASIC LTU Getting only 1 user at cost of $2400.00???
- Next by Date: strange disk state and corrupt new mail file
- Previous by thread: Re: Banana Republic (was Re: OpenVMS Book Wins award)
- Next by thread: Re: Banana Republic (was Re: OpenVMS Book Wins award)
- Index(es):
Relevant Pages
|
