# Message history (Beta) (/en/realtime-media/rtm/build/send-and-receive-messages/message-history/windows)

> For AI agents: see the complete documentation index at [llms.txt](/llms.txt).

The Signaling message history feature allows you to store messages when publishing them to a channel. For example, if a user joins a channel midway through a conversation, you can retrieve messages that were published before the user joined. You can configure the message retention period for each project, ranging from 1 day to permanent storage.

    When a message is published, it is stored using the channel name and the message timestamp. You can use this information to retrieve historical messages.

    <CalloutContainer type="info">
      <CalloutDescription>
        The historical message feature is currently available for User Channels and Message Channels, but not for Stream Channels.
      </CalloutDescription>
    </CalloutContainer>

    ## Prerequisites [#prerequisites-4]

    Before implementing this feature, ensure that you have:

    * Integrated the Signaling SDK in your project, and implemented the framework functionality from the [SDK quickstart](../../index) page.
    * Enabled the message history feature by contacting [support@agora.io](mailto\:support@agora.io). You can request a storage duration of 1, 7, 30, 90, or 365 days, or opt for permanent storage.

      <CalloutContainer type="info">
        <CalloutDescription>
          Changes to storage duration only affect future messages.
        </CalloutDescription>
      </CalloutContainer>

    ## Implement message history [#implement-message-history-4]

    This section shows how to store and retrieve messages from history.

    ### Store messages [#store-messages-4]

    To store a message on the server, set `setStoreInHistory` to `true` in the `publish()` method. The following example shows the minimum code to store a message published to a message channel:

    ```cpp
    uint64_t requestId = 0;
    std::string channelName = "chatRoom"
    std::string message = "Hello world!";

    PublishOptions options;
    options.storeInHistory = true;
    options.channelType = RTM_CHANNEL_TYPE_MESSAGE;
    options.messageType = RTM_MESSAGE_TYPE_STRING;

    rtmClient_->publish(channelName.c_str(), message.c_str(), message.size(), options,
                       requestId);
    ```

    To store a message in the history of a user channel, use the same parameter:

    ```cpp
    uint64_t requestId = 0;
    std::string userId = "Tony"
    std::string message = "Hello world!";

    PublishOptions options;
    options.storeInHistory = true;
    options.channelType = RTM_CHANNEL_TYPE_USER;
    options.messageType = RTM_MESSAGE_TYPE_STRING;

    rtmClient_->(userId.c_str(), message.c_str(), message.size(), options,
                requestId);
    ```

    ### Retrieve messages [#retrieve-messages-4]

    The SDK provides the `getMessages()` method to retrieve up to 100 history messages at a time. You can filter messages by setting the `start` and `end` parameters to define a time range. To retrieve only the most recent messages, such as those sent between the last offline time and now, set only the `end` parameter.

    The following example retrieves the latest 50 messages sent before a specific time:

    ```cpp
    uint64_t requestId = 0;
    std::string channelName = "chatRoom";

    GetHistoryMessagesOptions options;
    options.messageCount = 50;
    options.end = 1688978391800;

    rtmClient_->getHistory()->getMessages(channelName.c_str(), RTM_CHANNEL_TYPE_MESSAGE,
                                         options, requestId);
    ```

    The `result` includes a `newStart` field, which indicates whether there are unread messages i the history:

    * If `newStart` is `0`, all messages have been retrieved.
    * If `newStart` is not `0`, use this value as the new `start` parameter in the next `getMessages()` call to continue retrieving messages.

    The following use-cases show how to specify the `start` and `end` parameters to retrieve messages in a specific range:

    #### Retrieve before a start timestamp [#retrieve-before-a-start-timestamp-4]

    | Parameter | Behavior                                                                                |
    | --------- | --------------------------------------------------------------------------------------- |
    | `start`   | Returns messages sent before the specified timestamp. The timestamp itself is excluded. |

    ```text
    Timeline:
    [Older messages] ------------ start timestamp ------------ [Newer messages]
    [             ←-- n messages]
    ```

    #### Retrieve messages up to an end timestamp [#retrieve-messages-up-to-an-end-timestamp-4]

    | Parameter | Behavior                                                                             |
    | --------- | ------------------------------------------------------------------------------------ |
    | `end`     | Returns the n most recent messages sent up to and including the specified timestamp. |

    ```text
    Timeline:
    [Older messages] ------------ end timestamp ------------ [Newer messages]
                                           [  ←-- n messages]
    ```

    #### Retrieve messages between two timestamps [#retrieve-messages-between-two-timestamps-4]

    | Parameter | Behavior                                                  |
    | --------- | --------------------------------------------------------- |
    | `start`   | Returns messages sent before this timestamp (excluded).   |
    | `end`     | Returns messages sent up to and including this timestamp. |

    ```text
    Timeline:
    [Older messages] ---- end timestamp ------------ start timestamp ---- [Newer messages]
                                   [ ←-- n messages]
    ```