Invisible wrote:
> Why would people do "work" (especially such mundane work) for a nickle? 

I don't know. Most of it seems to not be from people in third-world 
a-nickel-is-a-lot-of-money countries either.

> Why would companies pay for results which are likely to be garbage 
> anyway? 

You don't pay till you check the results. Or you send the same job out three 
times and make sure all three answers come back similar. Which isn't hard 
when it only costs a nickel to start with.

> How does Amazon make money out of this? 

They take a cut.

> OK, so... it's a message delivery system. 

Yes.

> Where do the messages come 
> from? Where does it deliver them to? What are they for? Why would you 
> pay money for this? etc.

Read the APIs.

> One wonders how a small online shop such as Amazon ends up with such 
> vast computational resources that it can profitably hire out the spare 
> capacity, but still...

Small?  I suppose they started small.  Winter a year ago, they were 
fulfilling 43 orders per second the week before Christmas.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Also... what precisely *is* a "web service" anyway? I can't find any 
useful answers online.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> Also... what precisely *is* a "web service" anyway? I can't find any 
> useful answers online.

It currently means a service provided to you over the internet. I.e., we'll 
run the program, you access it remotely.

Alternately, if you're talking about "Web Service", it could also mean using 
SOAP over HTTP to remotely invoke services at a remote machine. It's a bit 
of an overloaded term.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Darren New wrote:

> It currently means a service provided to you over the internet. I.e., 
> we'll run the program, you access it remotely.
> 
> Alternately, if you're talking about "Web Service", it could also mean 
> using SOAP over HTTP to remotely invoke services at a remote machine. 
> It's a bit of an overloaded term.

Amazon appears to be talking about SOAP. It points to a W3 Schools 
tutorial, but it doesn't make any sense. (Neither does Wikipedia. But 
then, that's a horrid place to attempt to learn new technologies. It's 
reference material.)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> Amazon appears to be talking about SOAP. 

SOAP, conceptually, is pretty simple. You take the arguments to the 
procedure and wrap them up in XML. You put the function you're calling into 
the headers. You post the message (with appropriate crypto signatures if 
necessary) to the appropriate URL. You get back from the web server your 
answer, probably again wrapped up in XML.

WSDL is a way of specifying what arguments go where in the sending and 
returning XML.

Generally, you write the server end and have the IDE generate the WSDL file 
for it. You give the WSDL file to someone else, who hands it to *their* IDE, 
which writes the client stub. So it's basic remote procedure invocation, 
lathered up with a bunch of Web 2.0 buzzwords.

If you don't do the automation part, it's an awful technology. If you do the 
automation part, it's a convenient way of filling that niche. Most 
complaints about it are how hard it is to automate, or that it's the wrong 
way to do distributed computing.

In theory, SOAP supposedly runs over things other than HTTP. In practice, it 
doesn't, in part because they left out of SOAP some of the vital parts that 
HTTP provides (like cookies, for example).

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Darren New wrote:
> Orchid XP v8 wrote:
>> Amazon appears to be talking about SOAP. 
> 
> SOAP, conceptually, is pretty simple. You take the arguments to the 
> procedure and wrap them up in XML. You put the function you're calling 
> into the headers. You post the message (with appropriate crypto 
> signatures if necessary) to the appropriate URL. You get back from the 
> web server your answer, probably again wrapped up in XML.

So... you issue a command, and you receive a reply? And these are both 
formatted as XML?

Is the reply necessarily immediate?

If I'm understanding this correctly, that means that you can make Amazon 
start or stop a virtual server by sending a lump of XML to it over HTTP. 
Is that about right?

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
> So... you issue a command, and you receive a reply? And these are both 
> formatted as XML?

Yes. Think of it like a procedure call between machines.

> Is the reply necessarily immediate?

In theory, no. In practice, yes.

> If I'm understanding this correctly, that means that you can make Amazon 
> start or stop a virtual server by sending a lump of XML to it over HTTP. 
> Is that about right?

Exactly.  I have a library to do just that, only it uses the REST interface 
(which isn't really REST) to do so.

Also, http://console.aws.amazon.com/ lets you do it all from a web browser, 
or so they just announced. I haven't tried it.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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Darren New wrote:
>> Is the reply necessarily immediate?
> In theory, no. In practice, yes.

And by "immediate" I mean "returned over the same TCP connection the request 
went over."

SOAP designers will tell you how wonderful and flexible it all is. SOAP 
users don't do any of that because nobody has bothered to do any libraries 
to support SOAP over SMTP and things like that.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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>> So... you issue a command, and you receive a reply? And these are both 
>> formatted as XML?
> 
> Yes. Think of it like a procedure call between machines.

So it's a way of issuing server commands without needing a human to 
press the button?

>> Is the reply necessarily immediate?
> 
> In theory, no. In practice, yes.

Rather like the way HTTP responses are supposed to be "immediate"? 
(I.e., the browser hangs if it isn't.)

> Exactly.  I have a library to do just that, only it uses the REST 
> interface (which isn't really REST) to do so.

What's REST then?

> Also, http://console.aws.amazon.com/ lets you do it all from a web 
> browser, or so they just announced. I haven't tried it.

Yes, I noticed that. Currently only EC2 though. (?)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v8 wrote:
>> Yes. Think of it like a procedure call between machines.
> 
> So it's a way of issuing server commands without needing a human to 
> press the button?

Think of it like a procedure call between machines. :-)  I don't know what 
"button" you're talking about. "Buttons" are UI features. SOAP is a 
programming library mechanism. SOAP is a mechanism where you can write 
something like
    X = floob("Hello", 23)
and get back some data structure in X that was generated when "floob" and 
"Hello" and "23" were passed to some server somewhere. It doesn't matter 
whether that function call is invoked by pushing a button, a timer, a CLI, etc.

> Rather like the way HTTP responses are supposed to be "immediate"? 
> (I.e., the browser hangs if it isn't.)

Yes.

>> Exactly.  I have a library to do just that, only it uses the REST 
>> interface (which isn't really REST) to do so.
> 
> What's REST then?

Representational State Transfer.   A set of rules that almost nobody who 
claims to use REST actually follows.  But most everyone who calls their 
interfaces "REST" but which aren't means "just like SOAP, only without the 
ability to automate stub creation."  That is, you send us an XML request, 
and we return an XML answer, but you have to write all the code to parse out 
the results from the answer as a special case for each such service.

>> Also, http://console.aws.amazon.com/ lets you do it all from a web 
>> browser, or so they just announced. I haven't tried it.
> 
> Yes, I noticed that. Currently only EC2 though. (?)

As I said, I haven't looked.  The "s3fox" extension gives you access to 
Amazon S3 with a decent UI from firefox.

-- 
   Darren New, San Diego CA, USA (PST)
   Why is there a chainsaw in DOOM?
   There aren't any trees on Mars.

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