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Channels

KubeMQ Channel (Topic/Subject/Address/Destination) is a string-based representation of an endpoint or a target of a message.

Senders and Receivers

The core functionality of KubeMQ messaging is sending and receiving messages.
Senders (publishers) can send one or many messages (stream) to one or many destinations (Channels). Sending a message does not require the set up of any predefined destination.
Receiver (subscribers/listeners) can receive messages from one or more senders on the same channel or a wildcards channel. Before a Receiver can receive any messages, a Subscription function is needed to register his interest in receiving messages from a senders designation.

Format

A channel string can be formed from any UTF-8 characters with the following attributes:
  • Case sensitive, FOO and foo are different channel names
  • No white spaces allowed
  • Cannot be Blank (")
  • ., *, > are special characters for token hierarchies.
  • Cannot start with .
  • Can begin with > or * (for subscription receivers only)
  • Unlimited hierarchies

Hierarchies

Channels names can be separated by the . symbol to create messaging stream hierarchies.
One level hierarchy:
foo, USA, org are valid one level hierarchies.
Two-level hierarchies:
foo.bar, USA.NewYork, org.department are valid two-level hierarchies.
N level hierarchies:
foo.bar.A.B.C.> is valid n (n=6) level hierarchies.

Wildcards

KubeMQ supports two wildcards, * and >. Wildcards are used to subscribe to a group of channels’strings.

Asterisk *

Matching a single token in any hierarchy

Greater >

Matching one or more tokens at the tail of a channel
Examples:
Here some cases of channel subscription patterns and which types of messages with channels are accepted and ignored.
Channel Pattern
Messages Accepted
Messages Ignored
foo
foo
bar,zoo
foo.*
foo.bar,foo.ZOO
foo,foo.bar.zoo
foo.>
foo.bar.zoo
foo
foo.*.*.bar
foo.a.b.bar
foo.bar.zoo
foo*.>
foo.bar,foo1.bar`
foo\
>
any message
none