logon command

To help identify clients and users, it is recommended that clients send a logon command to the AMPS engine and specify a client name. By default, AMPS requires a logon command as the first command when a client connects.

AMPS only allows a single logon command for each connection. The logon command must be the first command sent over a new connection. Otherwise, AMPS performs an implicit logon, causing any other logon commands for the connection to be rejected.

In AMPS configurations where authentication is enabled, all connecting clients must issue a logon message with the username and password credentials specified in the command. Attempts to logon to an AMPS instance that do not contain the information required will be rejected and prohibited from issuing further commands until a successful logon has been placed.

If an AMPS client is connected to an instance that has a transaction log enabled, the ClientName specified must be unique for the instance. Only one client with the same name is allowed to connect to the instance at a given time. If an application logs on with the same ClientName and authenticated user name as an existing connection, AMPS assumes that the new logon is a reconnection from the existing connection and disconnects the existing connection. If an application logs on with the same ClientName as an existing connection but a different authenticated user name, the new logon will fail.

It is recommended that all logon commands request that a processed acknowledgment message be requested in the AckType header of the logon message. This will allow AMPS to communicate the result of the logon command to the client, allowing the client to determine how to best proceed.

info

The websocket protocol uses a different mechanism that contains the same information rather than sending a logon command.

Header Fields

The following table contains the header fields available to a logon command.

Field	Description
cmd	The command to be executed. Value: logon
client_name	A string identifier used to give a client a unique ID. AMPS does not limit the character set used in this name. However, the specific protocol may have character set limitations. 60East recommends that the client name is meaningful, short, human readable, and avoids using control characters, newline characters, or square brackets. The client name must be unique across the set of instances that share messages through replication. Otherwise messages may be lost since the client name is included in the process AMPS uses to form the unique identifier for messages published to AMPS.
ack_type	Acknowledgment type for the given command. Value is a comma separated list of one or more of the following: none, received or processed.
message_type	The message type for the connection. Required if the Transport accepts any message type.
user_id	The username passed into the AMPS authentication and entitlement module.
password	The password passed into the AMPS authentication and entitlement module.
correlation_id	A user-provided string that will be included in the log message recording this logon, and in the information provided for the connection in the administration interface. AMPS does not interpret this string or use the string for any other purpose. If this header is not present, AMPS does not store a value for the correlation id for this connection. The contents of this header must consist of characters that are legal in Base64 encoding.
version	The client library version (typical includes the language and build number) of the client making the connection. This version number is logged for the connection, but does not otherwise affect the connection.

Returns

A logon message specifying an AckType of received or processed will receive an ack message to acknowledge the message receipt. If a client requests an acknowledgment message, the header will also contain the ClientName which was part of the original logon message.

When requested, the logon command will result in a processed acknowledgment message. This returned acknowledgment is used in determining if a client was successfully authenticated against a server which has an authentication module enabled.

The following table contains the acknowledgment messages that can be returned by a logon command.

Acknowledgment	Description
none	No ack message is returned. This is the default behavior.
completed	Not supported at this time.
persisted	Not supported at this time.
processed	AMPS has processed the logon message.
received	The logon command has been received.
stats	Not supported at this time.

Options Field

The following table contains a list of the Options available and their definitions when used in the AMPS logon command.

Option	Description
none	This is the default Options type.
ack_conflation=interval	When provided, the interval at which AMPS conflates persisted acknowledgment messages for publishes sent on this connection. AMPS conflates persisted acknowledgment messages when a transaction log is configured for the instance. Default: 1s if no option is provided.
pretty	When provided and set to true, AMPS returns a formatted representation of the contents of the built-in binary message types rather than the original data.