6. Utility Commands¶
AMPS includes two commands to help applications function as expected.
flush¶
Sends a command to AMPS that returns an acknowledgment when all previous commands from this client have been processed. This command helps applications that use AMPS determine when AMPS has received all of the messages that have been sent, making it safe for the client to exit.
Header Fields¶
The following table contains the header
fields available to a flush
command.
Field | Description |
---|---|
Command |
The command to be executed. Value: flush . |
ClientName |
A string identifier used to give a client a unique id. |
AckType |
Acknowledgment type for the given command. Value
is a comma separated list of one or more of the
following: none , completed or
processed . |
Header fields supported by flush
Returns¶
A flush
message specifying an AckType
of completed
or
processed
will receive an ack
message when all previous messages
from this client have been processed by AMPS.
The following table contains the acknowledgment
messages that can be returned by a flush
command.
Acknowledgment | Description |
---|---|
none |
No ack message is returned. This is the
default behavior. |
completed |
All previous commands have been processed by AMPS. |
persisted |
All previous commands from this publisher have been persisted by AMPS (or have failed and produced the requested acknowledgments). |
processed |
AMPS has processed the flush message. |
received |
The flush command has been received. |
stats |
Not supported at this time. |
Acknowledgment messages supported by flush
heartbeat¶
Sends a command to AMPS that starts or refreshes a heartbeat timer. When a heartbeat timer is active, AMPS publishes periodic heartbeat messages to AMPS and expects the client to respond with a heartbeat message. If the client does not provide a heartbeat within the time specified, AMPS logs an error and disconnects the connection.
The AMPS client libraries automatically manage creating and returning heartbeats. It is rarely, if ever, necessary for an application to manage heartbeats. See the Developer Guide for the client library you are using for details.
Header Fields¶
The following table
contains the header fields available to a heartbeat
command.
Field | Description |
---|---|
Command |
The command to be executed. Value:
heartbeat . |
Options |
Specifies whether this command starts the timer or refreshes the timer. Valid options are:
|
Header fields supported by heartbeat
Returns¶
The heartbeat
message does not typically request an acknowledgment,
and therefore does not receive a response. The command can, however,
request acknowledgments as listed below.
Acknowledgment | Description |
---|---|
none |
Not supported at this time. |
completed |
Not supported at this time. |
parsed |
Not supported at this time. |
persisted |
Not supported at this time. |
processed |
AMPS has processed the heartbeat message. |
received |
AMPS has received the heartbeat message. |
stats |
Not supported at this time. |
Acknowledgment messages supported by heartbeat