GCN-XML and Dakota

[Roy Williams]

Alasdair

With email, for example, the sender makes the socket connection, sends 
the message, then disconnects.

Whereas here we have the receiver makes the connection, waits for a 
while, then the message comes and the receiver continues listening.

Whether we say one is common or uncommon is I suppose beside the point. 
Perhaps the real difference is short versus long-lived connection?

Roy

On 1/25/12 8:37 AM, Alasdair Allan wrote:
>
>> -- Each uses the uncommon idea that the receiver of the message
>> initiates the connection (usually the sender connects).
>
> The vTCP paradigm is that the received makes a client connection to the
> broker's server. Messages are pushed by the broker down these
> connection. I'm not entirely sure where you get the idea that this isn't
> the case?
>
> 3.2Broker to Subscriber
> When a subscriber wants to receive VOEvent message traffic, it opens a
> TCP connection to a broker. This connection is kept open continuously.
> When the broker receives a message, it relays a copy of the VOEvent
> message to all of the connected subscribers. Thus, a subscriber must
> continuously listen on the TCP connection and be prepared to receive
> VOEvent messages at any time, _even when it is busy processing a
> previously received VOEvent message_. When a subscriber receives a
> VOEvent message from its broker, it sends back a response. The response
> from the subscriber is a Transport message.
>
>
> This isn't "uncommon" that's how the majority of network protocols work,
> a client makes a connection to a server which it wants to get
> information from. That's how the WWW works after all?
>
> Al.
>

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