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 the start parameter (without end), you receive messages older than the start timetoken.
If you specify only the end parameter (without start), you receive messages from that end timetoken and newer.
If you specify both start and end, you retrieve messages between those timetokens (inclusive of the end value).

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:

this.pubnub.fetchMessages()
    .channels(List<String>)
    .maximumPerChannel(Integer)
    .start(Long)
    .end(Long)
    .includeMessageActions(Boolean)
    .includeMeta(Boolean)
    .includeMessageType(Boolean)
    .includeCustomMessageType(Boolean)
    .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	Timetoken delimiting the start (exclusive) of the time slice.
`end` Type: Long Default: n/a	Timetoken delimiting the end (inclusive) of the time slice.
`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:

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

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.

Method(s)

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

this.pubnub.deleteMessages()
    .channels(Array)
    .start(Long)
    .end(Long)

* required

Parameter	Description
`channels` * Type: Array Default: n/a	Channels to delete messages from.
`start` Type: Long Default: n/a	Timetoken delimiting the start (inclusive) of the time slice.
`end` Type: Long Default: n/a	Timetoken delimiting the end (exclusive) of the time slice.
`async` * Type: `Consumer<Result>` Default: n/a	`Consumer` of a `Result` of type `PNDeleteMessagesResult`.

Sample code

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.

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:

this.pubnub.messageCounts()
    .channels(Array)
    .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

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

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.

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)

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

this.pubnub.history()
    .channel(String)
    .reverse(Boolean)
    .includeTimetoken(Boolean)
    .includeMeta(Boolean)
    .start(Long)
    .end(Long)
    .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	Timetoken delimiting the start (exclusive) of the time slice.
`end` Type: Long Default: n/a	Timetoken delimiting the end (inclusive) of the time slice.
`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:

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

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)

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)

History paging example

Usage

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

Breaking changes in v9.0.0

Fetch history​

Requires Message Persistence

Method(s)​

Truncated response

Sample code​

Reference code

Returns​

Other examples​

Paging history responses​

Delete messages from history​

Requires Message Persistence

Required setting

Method(s)​

Sample code​

Other examples​

Delete specific message from history​

Message counts​

Requires Message Persistence

Unlimited message retention

Method(s)​

Sample code​

Returns​

Other examples​

Retrieve count of messages using different timetokens for each channel​

History (deprecated)​

Requires Message Persistence

Alternative method

Start & End parameter usage clarity

Method(s)​

Using the reverse parameter:

Sample code​

Returns​

PNHistoryItemResult​

Other examples​

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

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)​

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)​

History paging example​

Usage

Include timetoken in history​

Fetch history

Method(s)

Sample code

Returns

Other examples

Paging history responses

Delete messages from history

Method(s)

Sample code

Other examples

Delete specific message from history

Message counts

Method(s)

Sample code

Returns

Other examples

Retrieve count of messages using different timetokens for each channel

History (deprecated)

Method(s)

Sample code

Returns

PNHistoryItemResult

Other examples

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

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)

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)

History paging example

Include timetoken in history