TODO

This library will be used for communicating between different clients.

2 types: sources and sinks
sources: init the connection, request what data needed or to be exported
sink: based on that, decide what type of things to do (create forms, or display it)

for instance:
- a source wants to get a new value
it uses this library, request to get a new value
the sink that listens to this source, creates a new - say text element - and get the value, returns it back

- atm a source is connected to a sink
a source and transmits data to many sink, but a source can only listens for value from one sink

- there are different types of requests:
+ input: asks sink for a value
+ output: asks the sink to display value
+ inout: ask the sink for a value based on what is being displayed


The question here is shoud I take rappture's path ???
for instance:

<run>
#     <input>
#         <number id="Ef">
#             <units>eV</units>
#             <min>-10eV</min>
#             <max>10eV</max>
#             <default>0eV</default>
#             <current>3eV</current>
#         </number>
#     </input>
# </run>

then access it by input.number(Ef).current then I can change the current value, or query for its current value


This is very flexible, but again how do I display these ???? Does the user have to decide about the interface ?  -- user here means programmer

Yes, follow that i.e the library access elements by path, instead of send messages.

Another thing, should I make config (host/port) global ? or per connection
Decision: one connection
if an operation wants another conneciton, it has to define in its definition
use pool for that

when a request is send, it will be appended into an array to be serve

TODO: what if a lot of data expoting, then it will freeze the input channel ?
For now, just use one connection first. 

I guess the best thing about making this is we can decide whether to assign each "operation" a seperate connection or not. Make it an option then 

{
name: "group"
layout: "default",
comment: "vertical layout"
{
	op_name: "in1",
	host: "abc",
	port: 8080,
	seperate_connection: "yes", // seperation connection or not
	comment:"accesspath = group.in1"
	op_type:"in",
	data_type:"int",
	prompt:"what is the value",
	comment:"empty means default",
	group:"unique",
	 
}

{
name: "ingroup"
	{
		name:"out1"
		data_type: "binary",
		display_type: "graph/image/video/file",
		
	}
}
}