Message Persistence API for PubNub Python-asyncio 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 Requires that the Message Persistence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-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 Python-asyncio SDK:

  1. pubnub.history().channel(String).include_meta(True).reverse(Boolean).include_timetoken(Boolean).start(Int).end(Int).count(Int)
    ParameterTypeRequiredDefaultDescription
    channelStringYesSpecifies channel to return history messages from.
    include_metaBooleanNoFalseSpecifies whether or not the message's meta information should be returned.
    reverseBooleanOptionalFalseSetting to True will traverse the time line in reverse starting with the oldest message first.
    include_timetokenBooleanOptionalFalseWhether event dates timetokens should be included in response or not.
    startIntOptionalTimetoken delimiting the start of time slice (exclusive) to pull messages from.
    endIntOptionalTimetoken delimiting the end of time slice (inclusive) to pull messages from.
    countIntOptionalSpecifies the number of historical messages to return.
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:

envelope = await pubnub.history()\
    .channel('history_channel')\
    .count(100).future()
# handle messages stored at evelope.result.messages
# status is available as envelope.status

Returns

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

MethodTypeDescription
messagesListList of messages of type PNHistoryItemResult. See PNHistoryItemResult for more details.
start_timetokenIntStart timetoken.
end_timetokenIntEnd timetoken.

PNHistoryItemResult:

MethodTypeDescription
timetokenIntTimetoken of the message.
entryObjectMessage.

Other Examples

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

    envelope = await pubnub.history().channel("my_channel").count(3).reverse(True).future()

    Response: 

    {
    end_timetoken: 13406746729185766,
    start_timetoken: 13406746780720711,
    messages: [{
        crypto: None,
        entry: 'Pub1',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub2',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub2',
        timetoken: None
    }]
}

  2. 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): 

    envelope = await pubnub.history()\
    .channel("my_channel")\
    .start(13847168620721752)\
    .reverse(true)\
    .future()

    Response 

    {
    end_timetoken: 13406746729185766,
    start_timetoken: 13406746780720711,
    messages: [{
        crypto: None,
        entry: 'Pub4',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub5',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub6',
        timetoken: None
    }]
}

  3. 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): 

    envelope = await pubnub.history()\
    .channel("my_channel")\
    .count(100)\
    .start(-1)\
    .end(13847168819178600)\
    .reverse(True)\
    .future()

    Response: 

    {
    end_timetoken: 13406746729185766,
    start_timetoken: 13406746780720711,
    messages: [{
        crypto: None,
        entry: 'Pub4',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub5',
        timetoken: None
    },{
        crypto: None,
        entry: 'Pub6',
        timetoken: None
    }]
}

  4. History Paging Example

    Usage!

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

    async def get_all_messages(start_tt):
    envelope = await pubnub.history()\
        .channel('history_channel')\
        .count(100)\
        .start(start_tt)\
        .future()

    msgs = envelope.result.messages
    start = envelope.result.start_timetoken
    end = envelope.result.end_timetoken
    count = len(msgs)

    if count > 0:
        print("%d" % count)
        print("start %d" % start)
        print("end %d" % end)

    if count == 100:
        await get_all_messages(start)

loop = asyncio.get_event_loop()
loop.run_until_complete(get_all_messages(14759343456292767))

  5. Include timetoken in history response: 

    envelope = await pubnub.history()\
    .channel("my_channel")\
    .count(100)\
    .include_tometoken()
    .future()

Delete Messages from History

Requires Message Persistence add-on Requires that the Message Persistence add-on is enabled for your key. See this page on enabling add-on features on your keys:
https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-

Description

Removes the messages from the history of a specific channel.

Note

There is a setting to accept delete from history requests for a key, which you must enable by checking the Enable Delete-From-History checkbox in the key settings for your key in the Admin Portal.

Requires Initialization with secret key.

Method(s)

To Delete Messages from History you can use the following method(s) in the Python-asyncio SDK.

  1. pubnub.delete_messages().channel(String).start(Int).end(Int).future()
    ParameterTypeRequiredDefaultDescription
    channelStringYesSpecifies channels to delete messages from.
    startIntOptionalTimetoken delimiting the start of time slice (inclusive) to delete messages from.
    endIntOptionalTimetoken delimiting the end of time slice (exclusive) to delete messages from.

Basic Usage

envelope = yield from pubnub.delete_messages()\
    .channel("my-ch")\
    .start(123)\
    .end(456)
    .future()

Other Examples

  1. 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. e.g. if 15526611838554310 is the publish timetoken, pass 15526611838554309 in Start and 15526611838554310 in End parameters respectively as shown in the following code snippet.

    envelope = yield from pubnub.delete_messages()\
    .channel("my-ch")\
    .start(15526611838554310)\
    .end(15526611838554309)
    .future()
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