Question about XML based conversations

[David (7)]

Hello,

I'm not up to speed on using XML and could use some help. I get the idea of XML and the various parsers/generators available. I'm used to the concept of TCP/UDP conversations and haven't seen this discussed in an XML concept. I've been asked to put together a medium sized XML interface to one of my products and need to discuss the ideas with someone who has worked with this before.

I'll start by asking if all XML Conversations are presumed to look like simple HTTP Request-Response conversations.

I was aware of this tendancy but when I started to think about my conversations between my products they don't usually fit into the simple request-response category. In several cases the request will really be for a series of ongoing responses, like monitoring status changes in a system. I'm also quite used to opening a minimal number of conversations between computers and queuing multiple request-response conversations along the same channel. It seems wasteful to require a new conversation for every request-response transaction between systems.

Is it possible/useful to open a TCP connection between
machines and then transmit XML messages between the systems?

I've used SAX2 under MSXML to parse a file with multiple messages and can't figure out how to restart the parser for the second message.

My current level is just getting up to speed on the basics of using XML. I'm supposed to design an interface for another team to use my product that feels XML is best for them. I'd like to figure out what is reasonable and normal before inventing methods that they will not want to handle.

I'd also welcome any reading material on the subject, I've searched www.xml.org/.com and lots of other places and haven't found the magic keywords that get me to a description for solving the type of problem I'm trying to solve.

Thank you for your help,

David

 

[Andy Dingley]

I'll start by asking if all XML Conversations are presumed to look like simple HTTP Request-Response conversations.

I've never heard of "XML Conversations". If you're capitalising this, is it a proprietary technology ?

It sounds like you're re-inventing SOAP here, which is one part of the big web-services picture. It's not an "XML topic", because XML is deliberately a very small-scope protocol and things additional to it like this are described separately. However your basic idea is right; XML documents fly about by HTTP. It isn't always HTTP, and sometimes it might not even be XML, but that's the mainstream.

 

[David (7)]

I've never heard of "XML Conversations". If you're capitalising this, is it a proprietary technology ?

It sounds like you're re-inventing SOAP here, which is one part of the big web-services picture. It's not an "XML topic", because XML is deliberately a very small-scope protocol and things additional to it like this are described separately. However your basic idea is right; XML documents fly about by HTTP. It isn't always HTTP, and sometimes it might not even be XML, but that's the mainstream.

Thanks Andy.

I've read about XML for years and seen various uses. One used XML requests in files that were later replaced by XML responses in similarly named files. I've never, ever seen it mentioned that XML is generally for use over an HTTP conversation, though I'm aware that is where it is used most. I'd also not considered that everything was required to be request-response and stateless by most uses of XML encoding.

David

 

[Jesse Hager]

Hi David,

One thing you might want to check out is the Jabber/XMPP protocol, this is an open instant messaging protocol that uses continuous streams of XML elements for communication. Several people have used it as the transport protocol for other projects. It may give you some ideas on how to implement a non request-response protocol. Or maybe just grab one of the existing XMPP libraries and use it to send your own XML data

The main Jabber Site:
http://www.jabber.org

The core XMPP protocol spec (see the XML Streams section 4):
http://www.jabber.org/ietf/draft-ietf-xmpp-core-23.txt

The instant messaging part is here:
http://www.jabber.org/ietf/draft-ietf-xmpp-im-22.txt

Hope this helps.

 

[David (7)]

Hi David,

One thing you might want to check out is the Jabber/XMPP protocol, this is an open instant messaging protocol that uses continuous streams of XML elements for communication. Several people have used it as the transport protocol for other projects. It may give you some ideas on how to implement a non request-response protocol. Or maybe just grab one of the existing XMPP libraries and use it to send your own XML data

The main Jabber Site:
http://www.jabber.org

The core XMPP protocol spec (see the XML Streams section 4):
http://www.jabber.org/ietf/draft-ietf-xmpp-core-23.txt

The instant messaging part is here:
http://www.jabber.org/ietf/draft-ietf-xmpp-im-22.txt

Hope this helps.

Thanks Jesse. That sounds like what I was thinking of.