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Posted to dev@qpid.apache.org by Alan Conway <ac...@redhat.com> on 2016/02/23 17:15:23 UTC

[dispatch] Agreeing on terminology about directions.

Direction of message flow is tricky to describe in router
configuration. "in" and "out", "sender" and "receiver" all have
opposite meaning depending on whether you are thinking from a router or
client perspective.

Here's what I would propose based on the existing use of "in" and "out"
in the linkRoutePattern configuration. This is the opposite of how I
usually think of "in" and "out" but I suspect this is a 50/50 issue
where it doesn't matter which we pick as long as we pick one.

Note I'm using "relay" to mean router-initiated links, which currently
means waypoints and link-routes.

=======================
Directional terminology
=======================

Connections: can be established to the router (via listeners) or from
the router (via connectors) The direction that the connection was made
has no effect on how it can be used.

Links opened from outside the router are "client" links.  Links opened
by the router are "relay" links.

Links that receive messages from the router network are called *in*
links because messages flow from the network *into* a client or are
relayed *into* an external system.

Links that send messages *to* the router network are called "out" links
because messages flow *out* of clients or external systems to the
network.


Shout if I've got this wrong or if anyone has ideas for less ambiguous
terms than in/out or send/receive.


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Re: [dispatch] Agreeing on terminology about directions.

Posted by Ted Ross <tr...@redhat.com>.
On 02/23/2016 11:15 AM, Alan Conway wrote:
> Direction of message flow is tricky to describe in router
> configuration. "in" and "out", "sender" and "receiver" all have
> opposite meaning depending on whether you are thinking from a router or
> client perspective.
>
> Here's what I would propose based on the existing use of "in" and "out"
> in the linkRoutePattern configuration. This is the opposite of how I
> usually think of "in" and "out" but I suspect this is a 50/50 issue
> where it doesn't matter which we pick as long as we pick one.
>
> Note I'm using "relay" to mean router-initiated links, which currently
> means waypoints and link-routes.
>
> =======================
> Directional terminology
> =======================
>
> Connections: can be established to the router (via listeners) or from
> the router (via connectors) The direction that the connection was made
> has no effect on how it can be used.

If you run "qdstat -c" against a running router, it shows the 
connections with a direction.  "In" means the connection was established 
inbound to the router (via a listener).  "Out" means the connection was 
established outbound (via a connector).

The direction is expressed from the perspective of the router, not the 
connected endpoints.

>
> Links opened from outside the router are "client" links.  Links opened
> by the router are "relay" links.
>
> Links that receive messages from the router network are called *in*
> links because messages flow from the network *into* a client or are
> relayed *into* an external system.
>
> Links that send messages *to* the router network are called "out" links
> because messages flow *out* of clients or external systems to the
> network.
>

The opposite is the case.  Again if you use "qdstat -l", it shows link 
direction from the perspective of the router.  "In" links carry message 
deliveries into the router (are senders from the perspective of the 
endpoint).  "Out" links carry messages outbound from the router.

>
> Shout if I've got this wrong or if anyone has ideas for less ambiguous
> terms than in/out or send/receive.

The interesting points are 1) in which direction was the connection/link 
established, and 2) in which direction does the link carry message 
deliveries.  Perhaps there are better terms for established-inbound, 
flow-incoming, etc.

>
>
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Re: [dispatch] Agreeing on terminology about directions.

Posted by Michael Goulish <mg...@redhat.com>.

I think this is confusing, because the link origins
seem a little router-centric, while the link message 
directions are client-centric.

Why not make everything rclearly router-centric, in
this context.  Like this:


  links made by clients are "client links"  (or "client-originated links")
  links made by routers are "router links"  (or "router-originated links")

  links pointing at clients are pointing "outward"
  links pointing at routers are pointing "inward"
  links between two routers are "internal"





----- Original Message -----
> Direction of message flow is tricky to describe in router
> configuration. "in" and "out", "sender" and "receiver" all have
> opposite meaning depending on whether you are thinking from a router or
> client perspective.
> 
> Here's what I would propose based on the existing use of "in" and "out"
> in the linkRoutePattern configuration. This is the opposite of how I
> usually think of "in" and "out" but I suspect this is a 50/50 issue
> where it doesn't matter which we pick as long as we pick one.
> 
> Note I'm using "relay" to mean router-initiated links, which currently
> means waypoints and link-routes.
> 
> =======================
> Directional terminology
> =======================
> 
> Connections: can be established to the router (via listeners) or from
> the router (via connectors) The direction that the connection was made
> has no effect on how it can be used.
> 
> Links opened from outside the router are "client" links.  Links opened
> by the router are "relay" links.
> 
> Links that receive messages from the router network are called *in*
> links because messages flow from the network *into* a client or are
> relayed *into* an external system.
> 
> Links that send messages *to* the router network are called "out" links
> because messages flow *out* of clients or external systems to the
> network.
> 
> 
> Shout if I've got this wrong or if anyone has ideas for less ambiguous
> terms than in/out or send/receive.
> 
> 
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: dev-unsubscribe@qpid.apache.org
> For additional commands, e-mail: dev-help@qpid.apache.org
> 
> 

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