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]