# Manage server-side messages (/en/realtime-media/im/build/build-core-messaging/messages/retrieve-messages/android)

> 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]

    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.

    ## Prerequisites [#prerequisites]

    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]

    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]

    Call `asyncFetchConversationsFromServer` to retrieve conversations from the server with pagination. 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). 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 `getAllConversations` 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 `ChatOptions#isLoadEmptyConversations` 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).

    ```java
    String cursor = "";
    limit: The number of conversations that you expect to get on each page. The value range is [1,50].
    int limit = 40;
    List conversations = new ArrayList<>();
    doAsyncFetchConversationsFromServer(limit,cursor,conversations);

    private void doAsyncFetchConversationsFromServer(final int limit, final String cursor,List conversations){
        ChatClient.getInstance().chatManager().asyncFetchConversationsFromServer(limit, cursor, new ValueCallBack>() {
            @Override
            public void onSuccess(CursorResult value) {
                if (value != null ) {
                    List list = value.getData();
                    if (list != null && list.size() > 0) {
                        conversations.addAll(list);
                    }
                    String newCursor = value.getCursor();
                    if( !TextUtils.isEmpty(newCursor)) {
                        doAsyncFetchConversationsFromServer(limit, newCursor, conversations);
                    }
                }

            }

            @Override
            public void onError(int error, String errorMsg) {

            }
        });
    }
    ```

    ### Retrieve message history of the specified conversation [#retrieve-message-history-of-the-specified-conversation]

    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 sender list with `FetchMessageOption#setFromIds`.

    Refer to the following code sample:

    ```java
    String conversationId=" ";
    Conversation.ConversationType type=Conversation.ConversationType.Chat;
    FetchMessageOption option=new FetchMessageOption();
    //For example, save the retrieved messages to the local database.
    //option.setIsSave(true);
    //Since v1.4.0, for a group conversation you can retrieve messages sent by specific members.
    //For example, retrieve messages sent by two specific user IDs in the group.
    //List<String> fromIds = new ArrayList<String>();
    //fromIds.add("user1");
    //fromIds.add("user2");
    //option.setFromIds(fromIds);
    int pageSize = 40;
    String cursor = "";
    List messages = new ArrayList<>();
    doAsyncFetchHistoryMessages(conversationId,type,pageSize,cursor,option,messages);

    private void doAsyncFetchHistoryMessages(String conversationId,
                                             Conversation.ConversationType type,
                                             int pageSize,String cursor,
                                             FetchMessageOption option,
                                             List messages){
        ChatClient.getInstance().chatManager().asyncFetchHistoryMessages(conversationId, type, pageSize, cursor, option, new ValueCallBack>() {
            @Override
            public void onSuccess(CursorResult value) {
                if (value != null ) {
                    List list = value.getData();
                    if (list != null && list.size() > 0) {
                        messages.addAll(list);
                    }
                    String newCursor = value.getCursor();
                    if( !TextUtils.isEmpty(newCursor)) {
                        doAsyncFetchHistoryMessages(conversationId, type, pageSize, newCursor, option, messages);
                    }
                }
            }

            @Override
            public void onError(int error, String errorMsg) {

            }
        });
    }
    ```

    ### Search local messages sent by specific members [#search-local-messages-sent-by-specific-members]

    Since SDK v1.4.0, for a single conversation you can search the local database for messages that contain a keyword and are sent by specific members. You can specify up to 10 senders; to search messages from all senders, pass `null` or an empty list.

    ```java
    String conversationId = "user_or_group_id";
    Conversation conversation = ChatClient.getInstance()
            .chatManager()
            .getConversation(conversationId);
    if (conversation != null) {
        String keywords = "hello";
        long timeStamp = -1; // A value less than 0 means the search starts from the current time.
        int maxCount = 20;
        // Limit the senders to a maximum of 10. To not limit the senders, pass null or an empty list.
        List<String> senders = Arrays.asList("user1", "user2");
        conversation.asyncSearchMsgFromDB(
                keywords,
                timeStamp,
                maxCount,
                senders,
                Conversation.SearchDirection.UP,
                Conversation.ChatMessageSearchScope.CONTENT,
                new ValueCallBack<List<ChatMessage>>() {
                    @Override
                    public void onSuccess(List<ChatMessage> messages) {
                        for (ChatMessage message : messages) {
                            String msgId = message.getMsgId();
                            String from = message.getFrom();
                            long msgTime = message.getMsgTime();
                            // TODO: handle the search results
                        }
                    }

                    @Override
                    public void onError(int code, String error) {
                        // TODO: handle the error
                    }
                }
        );
    }
    ```

    ### Search local conversations by keyword [#search-local-conversations-by-keyword]

    Since SDK v1.4.0, you can search across all local conversations for messages that contain a keyword. The SDK returns a map of conversation IDs to the lists of matching message IDs. Each message ID list is ordered by message timestamp, in ascending or descending order according to the `direction` parameter.

    ```java
    String keyword = "Time";
    ChatClient.getInstance().chatManager().asyncLoadConversationMessagesWithKeyword(keyword, -1, null, Conversation.SearchDirection.UP, Conversation.ChatMessageSearchScope.CONTENT, new ValueCallBack<Map<String, List<String>>>() {
        @Override
        public void onSuccess(Map<String, List<String>> value) {
            EMLog.e(TAG, "asyncLoadConversationMessagesWithKeyword onSuccess value:" + value);
        }

        @Override
        public void onError(int error, String errorMsg) {
            EMLog.e(TAG, "asyncLoadConversationMessagesWithKeyword onError error:" + error + " errorMsg:" + errorMsg);
        }
    });
    ```

    ### Retrieve local messages by message ID [#retrieve-local-messages-by-message-id]

    Since SDK v1.4.0, you can pass one or more message IDs to retrieve messages from a single local conversation. You can pass a maximum of 20 message IDs at a time.

    ```java
    // messageIds: the list of message IDs. You can pass a maximum of 20 message IDs at a time.
    ChatClient.getInstance().chatManager().asyncLoadMessages(messageIds, conversationId, new ValueCallBack<List<ChatMessage>>() {
        @Override
        public void onSuccess(List<ChatMessage> value) {
            EMLog.e(TAG, "asyncLoadMessages onSuccess value:" + value);
        }

        @Override
        public void onError(int error, String errorMsg) {
            EMLog.e(TAG, "asyncLoadMessages onError error:" + error + " errorMsg:" + errorMsg);
        }
    });
    ```

    ### Pin a conversation [#pin-a-conversation]

    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:

    ```java
    ChatClient.getInstance().chatManager().asyncPinConversation(conversationId, true, new CallBack() {
        @Override
        public void onSuccess() {
        }

        @Override
        public void onError(int code, String error) {
        }
    });
    ```

    ### Pin a message [#pin-a-message]

    You can call `ChatManager#asyncPinMessage` to pin a message to the top of a one-to-one chat, chat group, or chat room. When the pinned status of a message changes, other members in the group or chat room conversation will receive the `MessageListener#onMessagePinChanged` event. In the case of multi-device login, the updated top status will be synchronized to other logged-in devices, and other devices will receive the `MessageListener#onMessagePinChanged` event, respectively.

    In group and chat room conversations, multiple users can pin the same message to the top. The latest pinned message will overwrite the earlier information. That is, the `MessagePinInfo` user ID and pin time will correspond to the latest pinned message.

    If the message is stored locally but deleted on the server due to expiration, the message will fail to be pinned to the top.

    For a single conversation, 20 messages can be pinned to the top by default.

    ```java
    ChatClient.getInstance().chatManager().asyncPinMessage(message.getMsgId(), new CallBack() {
        @Override
        public void onSuccess() {

        }

        @Override
        public void onError(int code, String error) {

        }

        @Override
        public void onProgress(int progress, String status) {

        }
    });

    ```

    ### Unpin a message [#unpin-a-message]

    You can call `ChatManager#asyncUnPinMessage` to unpin a message in a one-to-one chat, chat group, or chat room. As with pinned messages, other members of the group or chat room will receive the `MessageListener#onMessagePinChanged` event when the pinned message is unpinned. In the case of multi-device login, the updated pin status will be synchronized to other logged-in devices, and other devices will receive the `MessageListener#onMessagePinChanged` event, respectively.

    Any user in a group or room can unpin a message, regardless of who pinned it. After unpinning a message, `Message#pinnedInfo` is returned empty and the message is no longer included in the pinned message list.

    ```java
    ChatClient.getInstance().chatManager().asyncUnPinMessage(message.getMsgId(), new CallBack() {
        @Override
        public void onSuccess() {

        }

        @Override
        public void onError(int code, String error) {

        }

        @Override
        public void onProgress(int progress, String status) {

        }
    });
    ```

    ### Get pinned messages in a single conversation [#get-pinned-messages-in-a-single-conversation]

    You can call `ChatManager#asyncGetPinnedMessagesFromServer` to get the pinned messages from a single conversation from the server. The SDK returns messages in the reverse order of pinning.

    <CalloutContainer type="success">
      <CalloutDescription>
        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.
      </CalloutDescription>
    </CalloutContainer>

    ```java
    ChatClient.getInstance().chatManager().asyncGetPinnedMessagesFromServer(conversationId, new ValueCallBack>() {
        @Override
        public void onSuccess(List pinedMessages) {

        }

        @Override
        public void onError(int error, String errorMsg) {

        }
    });
    ```

    ### Get pinned details of a single message [#get-pinned-details-of-a-single-message]

    You can call `MessagePinInfo` 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, this class is returned empty.

    ```java
    MessagePinInfo emPinnedInfo = message.pinnedInfo();
    if(emPinnedInfo!=null) {
        long pinTime = emPinnedInfo.pinTime();
        String operatorId = emPinnedInfo.operatorId();
    }else{
        //If the value is empty, the message is in the unpinned state.
    }
    ```

    ### Delete historical messages from the server unidirectionally [#delete-historical-messages-from-the-server-unidirectionally]

    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.

    ```java
    // Delete messages by time stamp
    Conversation conversation = ChatClient.getInstance().chatManager().getConversation(username);
    conversation.removeMessagesFromServer(time, new CallBack() {
        @Override
        public void onSuccess() {}

        @Override
        public void onError(int code, String desc) {}
    });

    // Delete messages by message ID
    conversation.removeMessagesFromServer(msgIdList, new CallBack() {
        @Override
        public void onSuccess() { }

        @Override
        public void onError(int code, String desc) { }
    });
    ```

    ### Delete conversations and related messages from the server unidirectionally [#delete-conversations-and-related-messages-from-the-server-unidirectionally]

    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.

    ```java
    ChatClient.getInstance().chatManager().deleteConversationFromServer(conversationId, conversationType, isDeleteServerMessage, new CallBack() {
        @Override
        public void onSuccess() {

        }

        @Override
        public void onError(int code, String error) {
        }
    });
    ```

    ### Tag a conversation [#tag-a-conversation]

    To tag a conversation, use the `asyncAddConversationMark` method. This method allows you to add tags to both local and server-side conversations. 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:pageSize:completion` 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.

    <CalloutContainer type="info">
      <CalloutDescription>
        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.
      </CalloutDescription>
    </CalloutContainer>

    ```java
    String conversationId = "Derry";
    List ids=new ArrayList<>();
    ids.add(conversationId);
    ChatClient.getInstance().chatManager().asyncAddConversationMark(ids, Conversation.EMMarkType.MARK_0, new CallBack() {
        @Override
        public void onSuccess() {

        }

        @Override
        public void onError(int code, String error) {

        }
    });
    ```

    To use customized tags, use the following code:

    ```java
    Map mapping=new HashMap<>();
    mapping.put(Conversation.EMMarkType.MARK_0,"important");
    mapping.put(Conversation.EMMarkType.MARK_1,"normal");
    mapping.put(Conversation.EMMarkType.MARK_2,"unimportant");
    mapping.put(Conversation.EMMarkType.MARK_3,"boys");
    mapping.put(Conversation.EMMarkType.MARK_4,"girls");
    ……
    ```

    ### Remove conversation tag [#remove-conversation-tag]

    You can call `asyncRemoveConversationMark` to remove tag of 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.

    ```java
    String conversationId = "Derry";
    List ids=new ArrayList<>();
    ids.add(conversationId);
    ChatClient.getInstance().chatManager().asyncRemoveConversationMark(ids, Conversation.EMMarkType.MARK_0,new CallBack() {
        @Override
        public void onSuccess() {

        }

        @Override
        public void onError(int code, String error) {

        }
    });
    ```

    ### Query conversations from the server by the conversation tag [#query-conversations-from-the-server-by-the-conversation-tag]

    You can use the `asyncGetConversationsFromServerWithCursor` 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:

    ```java
    //All the query results are put into `result`.
    List result = new ArrayList<>();
    //cursor: The starting position of the query. Pass in an empty string for the first call of the method and the SDK starts to get from the conversation with the latest marked operation.
    String cursor = "";
    // filter: Conversation query options, including conversation marks and the number of conversations obtained per page (up to 10).
    // For example, query all conversations marked with Conversation.EMMarkType.MARK_0 on the server.
    ConversationFilter filter = new ConversationFilter(Conversation.EMMarkType.MARK_0, 10);
    doAsyncGetConversationsFromServerWithCursor(result, cursor, filter);

    private void doAsyncGetConversationsFromServerWithCursor(List result, @NonNull String cursor, @NonNull ConversationFilter filter) {
        ChatClient.getInstance().chatManager().asyncGetConversationsFromServerWithCursor(cursor, filter, new ValueCallBack>() {
            @Override
            public void onSuccess(CursorResult value) {
                List datas=value.getData();
                if(!CollectionUtils.isEmpty(datas)){
                    result.addAll(datas);
                }
                String cursor_ = value.getCursor();
                if(!TextUtils.isEmpty(cursor_)){
                    doAsyncGetConversationsFromServerWithCursor(result,cursor_,filter);
                }
            }

            @Override
            public void onError(int error, String errorMsg) {

            }
        });
    }
    ```

    ### Query local conversations by the conversation tag [#query-local-conversations-by-the-conversation-tag]

    For local conversations, you can call the `getAllConversations` method to obtain all local conversations and then perform conversation filtering yourself. The following is an example of querying all local conversations marked with `Conversation.EMMarkType.MARK_0`:

    ```java
    //All the query results are put into result.
    List result=new ArrayList<>();
    Map localConversations = ChatClient.getInstance().chatManager().getAllConversations();
    if(localConversations!=null&&!localConversations.isEmpty()){
        for(Conversation conversation:localConversations.values()){
            Set marks = conversation.marks();
            if(marks!=null&&!marks.isEmpty()){
                for(Conversation.EMMarkType mark:marks){
                    if(mark==Conversation.EMMarkType.MARK_0){
                        result.add(conversation);
                    }
                }
            }
        }
    }
    ```

    ### Get all tags of a local conversation [#get-all-tags-of-a-local-conversation]

    You can call `Conversation#marks` to get all the tags of a local conversation. The sample code is as follows:

    ```java
    Set conversationMarks = ChatClient.getInstance().chatManager().getConversation("conversationId").marks();
    ```

    ## Next steps [#next-steps]

    After implementing retrieving messages, you can refer to the following documents to add more messaging functionalities to your app:

    * [Message receipts](./message-receipts)