AMPS Protocol

The following table describes how the headers in the amps protocol are processed by AMPS.

Current releases of AMPS use a simplified JSON-like syntax for the amps protocol.

AMPS Message Header - Sorted by Name

AMPS Header Field	Abbreviation	Name
ack_type	a	AckType
password	pw	Password
bookmark	bm	Bookmark
batch_size	bs	BatchSize
client_name		ClientName
cmd	c	Command
cmd_id	cid	CommandId
correlation_id	x	CorrelationId
data_only		DataOnly
expiration	e	Expiration
filter	f	Filter
gseq		GroupSequenceNumber
heartbeat		Heartbeat
leaseperiod	lp	LeasePeriod
matches		Matches
msg_len	l	MsgLen
max_msgs		MaximumMessages
opts	o	Opts
orderby		OrderBy
query_id		QueryID
reason		Reason
records_deleted		RecordsDeleted
records_inserted		RecordsInserted
records_returned		RecordsReturned
records_updated		RecordsUpdated
seq	s	Sequence
send_empty		SendEmpty
send_keys		SendKeys
send_oof		SendOutOfFocus
sow_key	k	SowKey
sow_keys		SowKeys
status		Status
sub_id		SubscriptionId
sids		SubscriptionIds
src		Src
timeout_interval		TimeoutInterval
timestamp	ts	TransmissionTime
top_n		TopNRecordsReturned
topic_matches		TopicMatches
topic	t	Topic
use_ns		UseNamespaces
user_id		UserId
version	v	Version

Header Fields - Reference

This section provides a reference to the header fields that have been used in AMPS messages. Not all headers are present on all outgoing messages, and not all headers are processed on incoming commands. See the detailed message descriptions in this guide for descriptions of which fields are used on a given command or a given response from AMPS. Further, although this table lists the header fields defined in every protocol, current versions of AMPS may not use every header defined in this table (see the detailed message descriptions for which fields are relevant for a given command or response).

Name	Type	Definition
AckType	string	Acknowledgment type for the given command.
BatchSize	integer Default is 1 when not present.	Specifies the number of messages that are batched together when returning a query result.
Bookmark	string	A client-originated identifier used to mark a location in journaled messages.
ClientName	string	Used to identify a client. Useful for publishers that wish to identify the source of a publish, client status messages and for client heartbeats. Can be set with logon command.
Command	One of: publish subscribe sow sow_and_subscribe sow_delete unsubscribe flush heartbeat logon	Command to be executed.
CommandId	string	Client-specified command ID. The CmdId is returned by the engine in responses to commands to allow the client to correlate the response to the command.
CorrelationId	string, base64 encoded characters only	Opaque token set by an application and returned with the message.
DataOnly	Boolean (true or false)	If true, only send raw data to subscriber for a matching publish message, i.e. do not include FIX/NVFIX envelope.
Expiration	integer (seconds)	SOW expiration time if used in publish.
Filter	string, should wrap in CDATA	Content filter expression.
GracePeriod	integer (milliseconds)	Grace period after heartbeat interval is exceeded before client is considered in error state.
GroupSequenceNumber	integer	Group Sequence Number returned with each batch message of a SOW response.
Heartbeat	One of: start stop beat	Heartbeat command.
LeasePeriod	timestamp	For messages from a queue, the time at which the lease expires.
LogLevel	One of: info none	Set the log level. Deprecated Not used in current versions of AMPS.
Matches	integer	Returned in the acknowledgment to a SOW query that indicates number of matches.
MaximumMessages	integer greater than zero	Specifies the maximum number of messages within a batch publish.
MessageID	string, e.g. MAMPS–XYZ	Set by AMPS engine to tag every incoming message.
MessageLength	integer	Sent with messages that have data (a message body) to indicate the number of bytes in the message body.
MessageType	string One of the configured message types in AMPS.	Message type.
MsgLen	integer	Sent with messages that have data (a message body) to indicate the number of bytes in the message body.
Opts	string	A comma-delimited list of options on a specific command.
Password	string	Password used to authenticate with an AMPS server.
QueryID	string	SOW query identifier set by client to identify a query.
Reason	string	The failure message that appears when an acknowledgment returns a status or failure.
RecordsDeleted	integer	Used in conjunction with the stats acknowledgment, this is the number of records deleted from the SOW with a sow_delete command.
RecordsInserted	integer	Used in conjunction with the stats acknowledgment, this is the number of records inserted into the SOW.
RecordsUpdated	integer	Used in conjunction with the stats acknowledgment, this is the number of records updated in the SOW.
RecordsReturned	integer	Returned in the acknowledgment to an SOW query that indicates number of records in the store.
SendEmpty	Boolean (true or false); default is true	If true, empty messages that are published will be forwarded to matching subscriptions.
SendKeys	Boolean (true or false)	Option to instruct AMPS that a client would like to receive the SowKey(s) back.
SendOutOfFocus	Boolean (true or false)	If true, Out of Focus messages are sent for the SOW query.
SendSubscriptionIDs	Boolean (true or false)	If false, subscription identifiers will not be sent for a matched message.
Sequence	integer greater than zero	An integer that corresponds to the publish message sequence number. For more information see the Replicating Messages Between Instances chapter in the AMPS User Guide.
SowKey	string containing the digits of an unsigned long for AMPS-generated SOW keys arbitrary string in the base64 character set for user-provided SOW keys	A SowKey will accompany each message returned in an SOW batch. A SowKey may also be added to messages coming in on a subscription when the published message matches a record in the SOW. A publish command may contain a SOW key if the SOW for the topic is configured to accept user-provided SOW keys.
SowKeys	comma-separated list of SowKey values	Comma-separated list of SowKey values.
Status	One of: stopped alive timed out error	Used to indicate client status when client is monitored for heartbeats.
SubscriptionId	string, e.g. SAMPS-XYZ	The subscription identifier set by server when processing a subscription.
SubscriptionIds	string	Comma-separated list of SubIds sent from AMPS engine to identify which client subscriptions match a given publish message.
TimeoutInterval	integer	Used in conjunction with the heartbeat interval to set the timeout interval for a publisher.
TopNRecordsReturned	unsigned integer	The number of records to return. Note: If TopN is not equally divisible by the BtchSz, then more records will be returned so that the total number of records is equally divisible by the BtchSz setting.
Topic	string	Topic
TopicMatches	integer	Returned in the acknowledgment to an SOW query that indicates number of topic matches.
TransmissionTime	ISO-8601 date-time	Timestamp - Optionally set to time the message was processed by the server.
UseNamespaces	Boolean (true or false)	Use SOAP XML namespaces in all messages from the AMPS engine.
UserId	string	Used to identify the user ID of a command.
Version	string	Contains the version of the AMPS server.