Message Persistence API for PubNub Lua SDK

The PubNub Message Persistence Service provides real-time access to history for all messages published to PubNub. Each published message is timestamped to the nearest 10 nanoseconds, and is stored across multiple availability zones in several geographical data center locations. Stored messages can be encrypted with AES-256 message encryption, ensuring that they are not readable while stored on PubNub's network.

Messages can be stored for a configurable duration or forever, as controlled by the retention policy that is configured on your account. The following options are available: 1, 3, 5, 7, 15, or 30 days, and Forever.

History

Requires Message Persistence add-on

This method requires that the Message Persistence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

Description

This function fetches historical messages of a channel.

It is possible to control how messages are returned and in what order, for example you can:

• Search for messages starting on the newest end of the timeline (default behavior - reverse = false)
• Search for messages from the oldest end of the timeline by setting reverse to true.
• Page through results by providing a start OR end timetoken.
• Retrieve a slice of the time line by providing both a start AND end timetoken.
• Limit the number of messages to a specific quantity using the count parameter.

Start & End parameter usage clarity

If only the start parameter is specified (without end), you will receive messages that are older than and up to that start timetoken value. If only the end parameter is specified (without start) you will receive messages that match that end timetoken value and newer. Specifying values for both start and end parameters will return messages between those timetoken values (inclusive on the end value). Keep in mind that you will still receive a maximum of 100 messages even if there are more messages that meet the timetoken values. Iterative calls to history adjusting the start timetoken is necessary to page through the full set of results if more than 100 messages meet the timetoken values.

Method(s)

To run History you can use the following method(s) in the Lua SDK:

pubnub_obj:history(params)

Parameter	Type	Required	Description
params	table	Yes	Table of history parameters. See History Parameters for more details.

History Parameters

Properties	Type	Required	Default	Description
Channel	string	Yes	none	The channel to get history for.
callback	function(r)	Yes	none	The function to call with received history.
error	function(r)	Optional	function(r) end	The function to call on failure, with result.
start	integer or string	Optional	none	The timetoken to start history from.
stop	integer or string	Optional	none	The timetoken to stop history at.
reverse	boolean	Optional	false	Whether to get the history in reverse (from chronological) order.
count	integer	Optional	10	Maximum number of messages to get in history (cannot be more than 100).

Using the reverse parameter

Messages are always returned sorted in ascending time direction from history regardless of reverse. The reverse direction matters when you have more than 100 (or count, if it's set) messages in the time interval, in which case reverse determines the end of the time interval from which it should start retrieving the messages.

Basic Usage

Retrieve the last 100 messages on a channel:

pubnub_obj:history({    channel = "demo",    count = 100,    callback = function(response)        textout(response)    end,    error = function (response)        textout(response)    end})