# Manage server-side messages (/en/realtime-media/im/build/build-core-messaging/messages/retrieve-messages/unity) > For AI agents: see the complete documentation index at [llms.txt](/llms.txt). The Chat SDK stores historical messages on the chat server. When a chat user logs in from a different device, you can retrieve the historical messages from the server, so that the user can also browse these messages on the new device. Additionally, the Chat SDK supports adding tags to conversation, with a maximum of 20 tags allowed per conversation. This page introduces how to use the Chat SDK to retrieve, delete, and tag messages and conversations. ## Understand the tech [#understand-the-tech-6] The Chat SDK uses `ChatManager` to retrieve historical messages from the server. The following are the core methods: * `asyncFetchConversationsFromServer`: Retrieves a list of conversations stored on the server. * `asyncFetchHistoryMessages`: Retrieves historical messages of a conversation from the server according to `FetchMessageOption`, the parameter configuration class for retrieving historical messages. * `asyncPinConversation`: Pins conversations. * `asyncFetchPinnedConversationsFromServer`: Retrieves pinned conversations. * `asyncPinMessage`: Pins a message in a conversation. * `asyncUnPinMessage`: Unpin a message in a conversation. * `asyncGetPinnedMessagesFromServer`: Get a list of pinned messages in a conversation. * `removeMessagesFromServer`: One-way deletion of historical messages on the server based on message time or message ID. * `deleteConversationFromServer`: Deletes conversations and their historical messages from the server. * `asyncAddConversationMark`: Tags a conversation. * `asyncRemoveConversationMark`: Removes a conversation tag. * `asyncGetConversationsFromServerWithCursor`: Queries conversations from the server by a conversation tag. The Chat SDK uses `IChatManager` to retrieve historical messages from the server. The following are the core methods: * `GetConversationsFromServerWithPage`: Retrieve conversations stored on the server with pagination. * `FetchHistoryMessagesFromServerBy`: Retrieves historical messages of a conversation from the server according to `FetchServerMessagesOption`, the parameter configuration class for retrieving historical messages. * `PinConversation`: Pins a conversation. * `GetConversationsFromServerWithCursor`: Retrieves a list of pinned conversations. * `RemoveMessagesFromServer`: Deletes historical messages from the server unidirectionally. * `DeleteConversationFromServer`: Deletes conversations and their historical messages from the server. ## Prerequisites [#prerequisites-6] Before proceeding, ensure that you meet the following requirements: * You have integrated the Chat SDK, initialized the SDK and implemented the functionality of registering accounts and login. For details, see [Chat SDK quickstart](../../../../get-started-sdk). * You understand the API call frequency limits as described in [Limitations](../../limitations). ## Implementation [#implementation-6] This section shows how to implement retrieving conversations and messages. ### Retrieve a list of conversations from the server [#retrieve-a-list-of-conversations-from-the-server-6] Call `GetConversationsFromServerWithCursor` to retrieve conversations from the server with pagination. You can set the `pinOnly` parameter in this method to determine whether to retrieve the list of pinned conversations: * If `pinOnly` is set to `false`, you can retrieve the list of pinned and unpinned conversations. The SDK returns the conversation list in the reverse chronological order of when conversations are active (the timestamp of the last message in the conversation). * If `pinOnly` is set to `true`, you can only retrieve the list of pinned conversations. The SDK returns the pinned conversations in the reverse chronological order of when they were pinned. Up to 50 pinned conversations can be retrieved. In the conversation list, each conversation object contains the conversation ID, conversation type, whether the conversation is pinned, the pinned time (the value is 0 for an unpinned conversation), and the last message in the conversation. After the conversation list is retrieved from the server, the local conversation list will be updated accordingly. We recommend calling this method when the app is first installed, or when there is no conversation on the local device. Otherwise, you can call `LoadAllConversations` to retrieve conversations on the local device. For each end user, the server stores 100 conversations by default. When this limit is exceeded, new conversations will start overwriting the old ones. If the entire message history in a conversation expires, the conversation becomes empty. When pulling the conversation list from the server, these empty conversations are not included by default. To include them, set `Options#EnableEmptyConversation` to `true` when initializing the SDK. In this case, empty conversations will occupy the conversations pull quota, regardless of whether they are needed when pulling. To change this, contact [support@agora.io](mailto\:support@agora.io). ```csharp // limit: The number of conversations that you expect to get on each page. The value range is [1,50]. int limit = 10; string cursor = ""; bool pinOnly = false; // `false`：Get the list of all conversations; `true`: Get the list of only pinned conversations. SDKClient.Instance.ChatManager.GetConversationsFromServerWithCursor(pinOnly, cursor, limit, new ValueCallBack>( onSuccess: (result) => { // Traverse the obtained conversation list foreach (var conv in result.Data) { } // The cursor for the next request string nextCursor = result.Cursor; }, onError: (code, desc) => { } )); ``` ### Retrieve message history of the specified conversation [#retrieve-message-history-of-the-specified-conversation-3] After retrieving conversations, you can retrieve historical messages from the server. You can set the search direction to retrieve messages in the chronological or reverse chronological order of when the server receives them, the message type, the time period, the message sender, as well as whether to save the retrieved message to the local database. If you have integrated Chat SDK after June 8, 2023, you can retrieve historical messages even before joining the Chat Group. For earlier implementations, contact [support@agora.io](mailto\:support@agora.io) to enable this. The Agora Chat server stores the full message history for a certain period of time depending on your subscribed [Chat plan](./message-overview#limitations-of-message-storage-duration). After an end user logs back into Agora Chat, the servers automatically send offline messages to them, that is, messages transmitted when that end user was offline. Offline messages are a subset of the full message history stored on Agora Chat server. Sending only a subset of messages prevents distributing too many messages to a single device, which can overwhelm it and slow down the end user login. Agora Chat server stores and manages these offline messages for every end user in the following way: * 1:1 private chat: Store 500 offline messages by default; * Chat Group: Store 200 offline messages by default; * Chatroom: Doesn't store offline messages. However, by default, whenever an end user joins a chatroom, Agora Chat servers push the 10 latest messages/chatroom to them, and this number can be adjusted to 200 messages/chatroom without additional charges. After the GA release of Agora Chat 1.3, you can log in to Agora Console and enable the chatroom message history retrieval feature. After that, Agora Chat servers will stop automatically pushing chatroom messages to new members and you can follow the guidance below to retrieve chatroom message history. For users to receive more offline messages, use the client API or a webhook to sync with Agora Chat's server. End users can also store additional messages on their local database. To ensure data reliability, we recommend retrieving less than 50 historical messages for each method call. To retrieve more than 50 historical messages, call this method multiple times. Once the messages are retrieved, the SDK automatically updates these messages in the local database. We recommend that you retrieve 20 messages each time, with a maximum of 50. During paginated query, if the total number of messages that meet the query conditions is greater than the number of `pageSize`, the number of messages of `pageSize` will be returned. If it is less than the number of `pageSize`, the actual number will be returned. When the message query is completed, the number of returned messages is less than the number of `pageSize`. Since SDK v1.4.0, for a single group conversation you can retrieve messages sent by specific members (rather than all members) by setting the `FromIds` list in `FetchServerMessagesOption`. `FromIds` replaces the deprecated `From` attribute. Refer to the following code sample: ```csharp FetchServerMessagesOption option = new FetchServerMessagesOption(); option.IsSave = false; option.Direction = MessageSearchDirection.UP; // Since SDK v1.4.0, for a group conversation, set FromIds to retrieve messages sent by specific members. option.FromIds = new List { "id1", "id2" }; option.MsgTypes = new List(); option.MsgTypes.Add(MessageBodyType.TXT); option.MsgTypes.Add(MessageBodyType.VIDEO); option.StartTime = 1695720454000; option.EndTime = 1695720554000; SDKClient.Instance.ChatManager.FetchHistoryMessagesFromServerBy(conversationId, type, cursor, pageSize, option, new ValueCallBack>( onSuccess: (result) => { }, onError: (code, desc) => { } )) ; ``` ### Search local messages sent by specific members [#search-local-messages-sent-by-specific-members-5] Since SDK v1.4.0, for a single conversation you can load messages from the local database that are sent by specific members. ```csharp Conversation conv = SDKClient.Instance.ChatManager.GetConversation(conversationId, convType); conv.LoadMessagesWithScopeAndFromIds(keyword, timestamp, maxCount, fromIds, direction, scope, new ValueCallBack>( onSuccess: (list) => { }, onError: (code, desc) => { } )); ``` ### Search local conversations by keyword [#search-local-conversations-by-keyword-5] Since SDK v1.4.0, you can call `LoadConversationMessagesWithKeyword` to search across all local conversations for messages that contain a keyword. The SDK returns the matching conversation IDs and message IDs, ordered by message timestamp in ascending or descending order according to the `direction` parameter. ```csharp SDKClient.Instance.ChatManager.LoadConversationMessagesWithKeyword(keywords, timestamp, from, direction, scope, new ValueCallBack>>( onSuccess: (result) => { }, onError: (code, desc) => { } )); ``` ### Retrieve local messages by message ID [#retrieve-local-messages-by-message-id-5] Since SDK v1.4.0, you can call `LoadMessages` to retrieve one or more messages from a single local conversation by message ID. To retrieve a single message, call `LoadMessage`. ```csharp List messageIdList = new List { "msgId1", "msgId2" }; SDKClient.Instance.ChatManager.LoadMessages(messageIdList, conversationId, new ValueCallBack>( onSuccess: (messages) => { }, onError: (code, desc) => { } )); ``` ### Pin a conversation [#pin-a-conversation-6] To keep track of an important conversation, you can pin it to the top of your conversation list. You can pin up to 50 conversations. The pinned state is stored on the server. In a multi-device login use-case, if you pin or unpin a conversation, other login devices will receive the `CONVERSATION_PINNED` or `CONVERSATION_UNPINNED` events. Refer to the following code example to pin a conversation: ```csharp SDKClient.Instance.ChatManager.PinConversation(convId, isPinned, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Retrieve the pinned conversations from the server with pagination [#retrieve-the-pinned-conversations-from-the-server-with-pagination-4] End users can pin up to 50 conversations. After you call this API, the SDK returns the pinned conversations in the reverse chronological order of when they are pinned. Agora Chat servers store a list of conversations that remain active in the past 7 days, regardless of Agora Chat package subscription. A conversation is considered active if it is pinned or there are new messages in a conversation. Refer to the following code example to get a list of pinned conversations from the server with pagination: ```csharp // limit: The number of sessions returned per page. The value range is [1,50]. // cursor: The cursor position to start getting data. int limit = 10; string cursor = ""; bool pinOnly = true; // `false`: Get the list of all conversations; `true`: Get the list of only pinned conversations. SDKClient.Instance.ChatManager.GetConversationsFromServerWithCursor(pinOnly, cursor, limit, new ValueCallBack>( onSuccess: (result) => { // Traverse the obtained conversation list foreach (var conv in result.Data) { } // The cursor for the next query string nextCursor = result.Cursor; }, onError: (code, desc) => { } )); ``` ### Pin a message [#pin-a-message-6] To pin a message to the top of a one-to-one chat, chat group, or chat room, call `ChatManager#PinMessage` and set the `isPinned` parameter to `true`. When the pinned status of a message changes, other members in the one-to-one chat, group or chat room conversation receive the `IChatManagerDelegate#OnMessagePinChanged` event. In the case of multi-device login, the updated top status is synchronized to other logged-in devices, and other devices receive the `IChatManagerDelegate#OnMessagePinChanged` event, respectively. Multiple users can pin the same message to the top. The latest pinned message overwrites the earlier information. That is, the `PinnedInfo` user ID and pin time correspond to the last pinned message. If the message is stored locally but deleted on the server due to expiration, the message fails to be pinned to the top. For a single conversation, 20 messages can be pinned to the top by default. ```csharp bool isPinned = true; SDKClient.Instance.ChatManager.PinMessage(msgId, isPinned, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Unpin a message [#unpin-a-message-4] To unpin a message in a one-to-one chat, chat group, or chat room, call `ChatManager#PinMessage` and set the `isPinned` parameter to `false`. As with pinned messages, other members of the one-to-one chat, chat group or chat room receive the `IChatManagerDelegate#OnMessagePinChanged` event when the pinned message is unpinned. In the case of multi-device login, the updated pin status is synchronized to other logged-in devices, and other devices receive the `IChatManagerDelegate#OnMessagePinChanged` event, respectively. Any user in a one-to-one chat, group or room can unpin a message, regardless of who pinned it. After unpinning a message, `PinnedBy` and `PinnedAt` in `Message#PinnedInfo` are returned empty and set to `0`, respectively, and the message is no longer included in the pinned message list. ```csharp bool isPinned = false; SDKClient.Instance.ChatManager.PinMessage(msgId, isPinned, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Get pinned messages in a single conversation [#get-pinned-messages-in-a-single-conversation-4] You can call `ChatManager#GetPinnedMessagesFromServer` to get the pinned messages from a single conversation from the server. The SDK returns messages in the reverse order of pinning. If a message expires on the server or the user deletes it unilaterally from the server after pinning, such user will not be able to pull it when pulling roaming messages. However, this user and other users will be able to pull this message from the pinned message list.If the user withdraws a message after pinning, the message will be removed from the server; other users will not be able to pull it when they pull the pinned message list from the server. ```csharp SDKClient.Instance.ChatManager.GetPinnedMessagesFromServer(convId, new ValueCallBack>( onSuccess: (list) => { foreach (var it in list) { // Traverse the message list } }, onError: (code, desc) => { } )); ``` ### Get pinned details of a single message [#get-pinned-details-of-a-single-message-3] You can call `PinnedInfo` to get the pinned details of a single message. * If the message is pinned, this class returns the time of pinning and the user ID of the user who has pinned it. * If the message is not pinned, then `PinnedBy` is returned empty and `PinnedAt` is set to `0`. ```csharp // ... const msg: ChatMessage; const info = await msg.getPinInfo; // todo: Get the pin information of the message ``` ### Delete historical messages from the server unidirectionally [#delete-historical-messages-from-the-server-unidirectionally-6] Call `RemoveMessagesFromServer` to delete historical messages one way from the server. You can remove a maximum of 50 messages from the server each time. Once the messages are deleted, you can no longer retrieve them from the server. The deleted messages are automatically removed from your local device. Other chat users can still get the messages from the server. To use this function, you need to contact [support@agora.io](mailto\:support@agora.io) to enable it. ```csharp SDKClient.Instance.ChatManager.RemoveMessagesFromServer(convId, ctype, time, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); SDKClient.Instance.ChatManager.RemoveMessagesFromServer(convId, ctype, msgList, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Delete conversations and related messages from the server unidirectionally [#delete-conversations-and-related-messages-from-the-server-unidirectionally-6] Call `DeleteConversationFromServer` to delete conversations and their historical messages unidirectionally from the server. After the conversations and messages are deleted from the server, you can no longer get them from the server. The deleted conversations still exist on your local device, but the messages are automatically removed from the device. Other chat users can still get the conversations and their historical messages from the server. ```csharp SDKClient.Instance.ChatManager.DeleteConversationFromServer(conversationId, conversationType, isDeleteServerMessages, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Tag a conversation [#tag-a-conversation-3] To tag a conversation, use the `MarkConversations` method. This method allows you to add tags to both local and server-side conversations, that is, set the `isMark` parameter to 'true'. Each conversation can have up to 20 tags. This feature applies only to private chats and chat groups. After adding a tag, you can retrieve the tagged conversations from the server by calling the `GetConversationsFromServerWithCursor` method. The returned conversation objects will include the conversation tag, which you can obtain using the `marks` property. If the server conversation list reaches its limit (default 100 conversations per user), inactive conversations will be deleted based on conversation activity (timestamp of the latest message). Consequently, the conversation tags of these deleted conversations will also be removed. Adding tags to a conversation, such as stars, does not affect other logic of the conversation, such as the number of unread messages in it. ```csharp List list = new List(); list.Add("huanhuan"); bool isMarked = true; SDKClient.Instance.ChatManager.MarkConversations(list, isMarked, (MarkType)mark, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Remove conversation tag [#remove-conversation-tag-3] You can call `MarkConversations` and set the `isMark` parameter to 'false' to untag a conversation. Tags can be removed for up to 20 conversations at a time. Calling this method removes both the local and server-side tags. ```csharp List list = new List(); list.Add("huanhuan"); bool isMarked = false; SDKClient.Instance.ChatManager.MarkConversations(list, isMarked, (MarkType)mark, new CallBack( onSuccess: () => { }, onError: (code, desc) => { } )); ``` ### Query conversations from the server by the conversation tag [#query-conversations-from-the-server-by-the-conversation-tag-3] You can use the `GetConversationsFromServerWithCursor` method to retrieve a list of conversations from the server based on the tag. The SDK returns the conversation list in reverse order of the conversation tag's timestamp. Each conversation object includes the following information: * Conversation ID * Conversation type * Pinned status (whether it is pinned or not) * Pin time (For an unpinned conversation, the value is 0) * Conversation tag * Latest message After fetching the conversation list from the server, the local conversation list is updated accordingly: ```csharp SDKClient.Instance.ChatManager.GetConversationsFromServerWithCursor((MarkType)mark, cursor, limit, new ValueCallBack>( onSuccess: (result) => { foreach (var conv in result.Data) { //Iterate over the sessions in result.Data } }, onError: (code, desc) => { } )); ``` ### Query local conversations by the conversation tag [#query-local-conversations-by-the-conversation-tag-2] For local conversations, you can call the `LoadAllConversations` method to obtain all local conversations and then perform conversation filtering yourself. The following is an example of querying all local conversations marked with `EMConversation.EMMarkType.MARK_0`: ```csharp // All final query results are put into result. List result = new List(); List localConversations = SDKClient.Instance.ChatManager.LoadAllConversations(); foreach(var conv in localConversations) { List Marks = conv.Marks(); foreach(var mark in Marks) { if (MarkType.MarkType0 == mark) { result.Add(conv); } } } ``` ### Get all tags of a local conversation [#get-all-tags-of-a-local-conversation-2] You can call `Conversation#Marks` to get all the tags of a local conversation. The sample code is as follows: ```csharp Conversation conv = SDKClient.Instance.ChatManager.GetConversation("conversationId", conversationType); List Marks = conv.Marks(); ``` ## Next steps [#next-steps-6] After implementing retrieving messages, you can refer to the following documents to add more messaging functionalities to your app: * [Message receipts](./message-receipts)