Failover

This module contains failover subscription and broadcast APIs. Any instance can subscribe to multiple topics and manage callbacks on them. The ALL keyword can be used to set callbacks to run for each topic in addition to any specific ones defined.

Process can publish to specific topics or to all processes using the ALL keyword.

.px.rpl.addCallback

Register a topic handler. Function must take two parameters; topic(symbol), payload (dict)

Parameters:

Name	Type	Description
topic	symbol	Event topic
callback	symbol	Function name

Example:

 .ex.opsHandler:{[topic; payload] 0N!(topic; payload);}
 .px.rpl.addCallback[`OPS; `.ex.opsHandler]

.px.rpl.broadcast

Broadcast a failover event

Parameters:

Name	Type	Description
topic	symbol	Event topic
msg	string	Audit message
payload	dict	Event payload

Example: Specific topic

 prefs:`ds_rte_ops_b`ds_rte_ops_c`ds_rte_ops_a
 .px.rpl.broadcast[`OPS; ""; enlist[`procs]!enlist prefs]

Example: Publish to all instances

 .px.rpl.broadcast[`ALL; "Server down"; enlist[`server]!enlist `prod1]

.px.rpl.removeCallback

Removes a topic handler

Parameters:

Name	Type	Description
topic	symbol	Event topic
callback	symbol	Function name

Example:

 .ex.opsHandler:{[topic; payload] 0N!(topic; payload);}
 .px.rpl.addCallback[`OPS; `.ex.opsHandler]
 .px.rpl.removeCallback[`OPS; `.ex.opsHandler]

.px.rpl.subTopics

Subscribes to failover topic broadcasts

Parameter:

Name	Type	Description
topics	symbol[]	Subscription topics

Example:

 .px.rpl.subTopics[`QR`OPS]

.px.rpl.unsubTopics

Removes subscriptions to failover topic broadcasts

Parameter:

Name	Type	Description
topics	symbol[]	Subscription topics

Example:

 .px.rpl.unsubTopics[`QR`OPS]