Re: [Visionaries] Local RPC

[Dean Michael Berris]

hi peter,

Peter Minten wrote:
> Hi folks,
>
> I've been thinking about a way to connect WebScheme and C# code. A fast approach
> would be direct C type calls. Disadvantage is that a lot of type checking and
> conversion has to be done. A flexible approach would be XML-RPC, but that's even
> slower.

i think here we have to strike a balance between flexibility and efficiency. 
something very flexible (like XML) at most times would be very ineefficient. 
take for example, if a new language with new data types would be adopted into 
the DotGNU system, would the specification for the inter-language function call 
binary protocol have to comply with the new data types? does the language have 
to adapt to the fairly rigid and efficient structure of a binary protocol 
defined? how about backward compatibility?

these IMHO are issues that may easily addressed with the use of XML and well 
defined and carefully structured DTD's for the sake of compliance and 
correctness of transactions between any two parties.

> I believe a mix form can be used for languages on one box to communicate. The
> basic idea is that XML-RPC is pretty good, but the XML needs to be replaced by a
> binary protocol (can be parsed faster). Another idea is that for every object
> that cannot be easily translated tickets are used.

i would like to agree, but however again i point out the tradeoff between 
flexibility and efficiency. would you sacrifice any of the two for the other? 
maybe in situations when a broader spectrum of tools would want to communicate 
with one another, a standard way of communication must be defined. this has 
already been done for us by XML, offering a framework for structured 
communication to be possible between seemingly different parties.

i mean, in a broader sense, what if DotGNU adapted pascal or delphi into the 
framework, would the specifications for the binary format change to take into 
consideration the quirks of the pascal boolean, or the objects defined in delphi?

> The details of the system have to be worked out, but I'm confident that this
> will make inter language calls much easier.

i also think it would, however a sacrifice for flexibility is very evident. what 
if bit fields were being send between two languages? if app A coded in language 
A created a bit field which is part of an object, which is needed by another app 
B coded in language C, how will the binary protocol make it happen?

although this is a special case i may say, more metadata and language specific 
conversion information would be squeezed into XML which gives it the flexibility 
to be able to handle the job in a more standard way.

i am currently working on a middleman server called XML Generic Object Server 
(xmlgos) -- which was and is still hosted in sourceforge, but is still in an 
alpha non-working state -- which specifically caters to these instances.

basically, xmlgos will sit as 1) a repository of xml documents in transit, 2) a 
persistent object storage for applications, and 3) as a communication medium for 
a wide range of applications. what it would basically do is/are:
	- accept data feeds from client and coat them in XML, using administrator 
exported "handler DTD's" and "conversion DTD's".
        - (initially) host static non-rpc'ing XML documents :: like a webserver
	- handle tunneling capabilities where direct feeds from app A to app B will be 
handled through "channels". all data transmitted, will be coated or wrapped in 
XML, and would be parsed/interpreted/executed on the recieving ends. (of course 
encryption need not be mentioned... ;-) )

interfacing the xmlgos is trough 2 ways -- interactive sessions (to cater to 
scripting languages) and an API which will be developed in languages that will 
be making use of the functionality offered by xmlgos.

i am currenlty figuring out the security model, the authentication method, as 
well as on how to use SSL in the correct way. i've pretty much figured out the 
protocol to be used, as well as very crude DTD's.

if anybody wants to help out or just get more details, i'd love to put what i 
have in mind on the list.

have a nice one everyone! =)

oh, and BTW, it's really not just for local RPC. i was initially thinking of it 
as a webservice, but then i figured it would be more efficient if it was run as 
a standalone server open to all the applications (not only DotGNU apps) on the 
local machine and the network.

--
-=[mikhail]=-

aka Dean Michael C. Berris
home +63 49 5680142
work +63 49 5680024
http://free.net.ph/Members/mikhailberis
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