Message Persistence API for Java SDK

Breaking changes in v9.0.0

PubNub Java SDK version 9.0.0 unifies the codebases for Java and Kotlin SDKs, introduces a new way of instantiating the PubNub client, and changes asynchronous API callbacks and emitted status events. These changes can impact applications built with previous versions (< 9.0.0) of the Java SDK.

For more details about what has changed, refer to Java/Kotlin SDK migration guide.

Message Persistence gives you real-time access to the history of messages published to PubNub. Each message is timestamped to the nearest 10 nanoseconds and stored across multiple availability zones in several geographic locations. You can encrypt stored messages with AES-256 so they are not readable on PubNub’s network. For details, see Message Persistence.

You control how long messages are stored through your account’s retention policy. Options include: 1 day, 7 days, 30 days, 3 months, 6 months, 1 year, or Unlimited.

You can retrieve the following:

• Messages
• Message reactions
• Files (using the File Sharing API)

Fetch history

Requires Message Persistence

Enable Message Persistence for your key in the Admin Portal. See how to enable add-on features.

Fetch historical messages from one or more channels. Use includeMessageActions to include message actions.

You control how messages are returned and in what order:

• If you specify only start, you receive messages older than that timetoken. start is the newer boundary of the query (exclusive).
• If you specify only end, you receive messages newer than or equal to that timetoken. end is the older boundary of the query (inclusive).
• If you specify both start and end, start must be a higher timetoken than end. Results contain messages between those timetokens, excluding the message at start and including the message at end.

How to use the start and end parameters

PubNub retrieves messages by searching backward through time (newest to oldest). Because of this, the parameter names are the reverse of their intuitive meaning:

• start is the newer boundary (higher timetoken value) - search begins here, exclusive
• end is the older boundary (lower timetoken value) - search stops here, inclusive

When you provide both parameters, start must be a higher timetoken than end.

9:00 AM10:00 AM11:00 AM11:59 AM

Results are always returned in oldest-first order.

You can receive up to 100 messages for a single channel. For multiple channels (up to 500), you can receive up to 25 messages per channel. If more messages match the time range, make iterative calls and adjust the start timetoken to page through the results.

Method(s)

Use the following method(s) in the Java SDK:

1this.pubnub.fetchMessages()
2    .channels(List<String>)
3    .maximumPerChannel(Integer)
4    .start(Long)
5    .end(Long)
6    .includeMessageActions(Boolean)
7    .includeMeta(Boolean)
8    .includeMessageType(Boolean)
9    .includeCustomMessageType(Boolean)
10    .includeUUID(Boolean)

* required

Parameter	Description
channels * Type: List<String> Default: n/a	Channels to fetch history messages from (up to 500).
maximumPerChannel Type: Integer Default: 100 or 25	Number of historical messages to return. Default and maximum are 100 (single), 25 (multi), and 25 with includeMessageActions.
start Type: Long Default: n/a	Newer boundary of the query (exclusive). Retrieval begins at this timetoken and moves backward in time. Must be a higher timetoken value than end when both are provided.
end Type: Long Default: n/a	Older boundary of the query (inclusive). Retrieval stops at this timetoken. Must be a lower timetoken value than start when both are provided.
includeMessageActions Type: Boolean Default: false	Whether to retrieve history messages with message actions. If true, limited to one channel and 25 messages. Default is false.
includeMeta Type: Boolean Default: false	Whether to include the meta object (if provided at publish time) in the response.
includeMessageType Type: Boolean Default: true	Whether to pass true to include message type. Default is true.
includeCustomMessageType Type: Boolean Default: false	Whether to retrieve messages with the custom message type. See Retrieving Messages.
includeUUID Type: Boolean Default: true	Whether to receive the publisher uuid. Default is true.
async * Type: Consumer<Result> Default: n/a	Consumer of a Result of type PNFetchMessagesResult.

Truncated response

If you fetch messages with message actions, the response may be truncated when internal limits are reached. If truncated, a more property is returned with additional parameters. Make iterative calls to history, adjusting the parameters to fetch more messages.

Sample code

Reference code

This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document.

Retrieve the last message on a channel:

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Returns

The fetchMessages() operation returns a list of PNFetchMessagesResult objects, each containing the following operations:

Method	Description
getMessage() Type: JsonElement	Message content.
getMeta() Type: JsonElement	Message metadata if any, and if requested via includeMeta(true).
getTimetoken() Type: Long	Publish timetoken.
getActionTimetoken() Type: Long	Timestamp when the message action was created.
getActions() Type: HashMap	Actions data of the message, if any, and if requested via includeMessageActions(true).
getMessageType() Type: Integer	Message type 0 - message, 1 - signal, 2 - object, 3 - message action, 4 - files
getCustomMessageType() Type: String	The custom message type.
getUuid() Type: String	UUID of the publisher

Other examples

Paging history responses

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Delete messages from history

Requires Message Persistence

Enable Message Persistence for your key in the Admin Portal. See how to enable add-on features.

Remove messages from the history of a specific channel.

Required setting

Enable Delete-From-History for your key in the Admin Portal and initialize the SDK with a secret key.

How to use the start and end parameters

PubNub retrieves messages by searching backward through time (newest to oldest). Because of this, the parameter names are the reverse of their intuitive meaning:

• start is the newer boundary (higher timetoken value) - search begins here, exclusive
• end is the older boundary (lower timetoken value) - search stops here, inclusive

When you provide both parameters, start must be a higher timetoken than end.

9:00 AM10:00 AM11:00 AM11:59 AM

Results are always returned in oldest-first order.

Method(s)

Use the following method(s) in the Java SDK:

1this.pubnub.deleteMessages()
2    .channels(Array)
3    .start(Long)
4    .end(Long)

* required

Parameter	Description
channels * Type: Array Default: n/a	Channels to delete messages from.
start Type: Long Default: n/a	Newer boundary of the query (exclusive). Must be a higher timetoken value than end when both are provided.
end Type: Long Default: n/a	Older boundary of the query (inclusive). Must be a lower timetoken value than start when both are provided.
async * Type: Consumer<Result> Default: n/a	Consumer of a Result of type PNDeleteMessagesResult.

Sample code

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Other examples

Delete specific message from history

To delete a specific message, pass the publish timetoken (received from a successful publish) in the End parameter and timetoken +/- 1 in the Start parameter. For example, if 15526611838554310 is the publish timetoken, pass 15526611838554309 in Start and 15526611838554310 in End parameters respectively as shown in the following code snippet.

1

Message counts

Requires Message Persistence

Enable Message Persistence for your key in the Admin Portal. See how to enable add-on features.

Return the number of messages published since the given time. The count is the number of messages with a timetoken greater than or equal to channelsTimetoken.

Unlimited message retention

Only messages from the last 30 days are counted.

Method(s)

Use the following method(s) in the Java SDK:

1this.pubnub.messageCounts()
2    .channels(Array)
3    .channelsTimetoken(Array)

* required

Parameter	Description
channels * Type: Array Default: n/a	Channels to fetch the message count.
channelsTimetoken * Type: Array Default: n/a	Array in the same order as channels; a single timetoken applies to all channels; otherwise, lengths must match exactly.
async * Type: Consumer<Result> Default: n/a	Consumer of a Result of type PNMessageCountResult.

Sample code

1

Returns

The operation returns a PNMessageCountResult which contains the following operations

Method	Description
getChannels() Type: Map<String, Long>	A map with values of Long for each channel. Channels without messages have a count of 0. Channels with 10,000 messages or more have a count of 10000.

Other examples

Retrieve count of messages using different timetokens for each channel

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History (deprecated)

Requires Message Persistence

Enable Message Persistence for your key in the Admin Portal. See how to enable add-on features.

Alternative method

This method is deprecated. Use fetch history instead.

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.

Method(s)

Use the following method(s) in the Java SDK:

1this.pubnub.history()
2    .channel(String)
3    .reverse(Boolean)
4    .includeTimetoken(Boolean)
5    .includeMeta(Boolean)
6    .start(Long)
7    .end(Long)
8    .count(Integer);

* required

Parameter	Description
channel * Type: String Default: n/a	Channel to return history messages from.
reverse Type: Boolean Default: false	Traverse from oldest to newest when set to true.
includeTimetoken Type: Boolean Default: false	Whether to include message timetokens in the response.
includeMeta Type: Boolean Default: false	Whether to include the meta object (if provided at publish time) in the response.
start Type: Long Default: n/a	Newer boundary of the query (exclusive). Retrieval begins at this timetoken and moves backward in time. Must be a higher timetoken value than end when both are provided.
end Type: Long Default: n/a	Older boundary of the query (inclusive). Retrieval stops at this timetoken. Must be a lower timetoken value than start when both are provided.
count Type: Int Default: 100	Number of historical messages to return.
async * Type: Consumer<Result> Default: n/a	Consumer of a Result of type PNHistoryResult.

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.

Sample code

Retrieve the last 100 messages on a channel:

1

Returns

The history() operation returns a PNHistoryResult which contains the following operations:

Method	Description
getMessages() Type: List<PNHistoryItemResult>	List of messages of type PNHistoryItemResult. See PNHistoryItemResult for more details.
getStartTimetoken() Type: Long	Start timetoken.
getEndTimetoken() Type: Long	End timetoken.

PNHistoryItemResult

Method	Description
getTimetoken() Type: Long	Timetoken of the message.
getEntry() Type: JsonElement	Message.

Other examples

Use history() to retrieve the three oldest messages by retrieving from the time line in reverse

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Use history() to retrieve messages newer than a given timetoken by paging from oldest message to newest message starting at a single point in time (exclusive)

1

Use history() to retrieve messages until a given timetoken by paging from newest message to oldest message until a specific end point in time (inclusive)

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History paging example

Usage

You can call the method by passing 0 or a valid timetoken as the argument.

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Include timetoken in history

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