Overview

SDK provides a complete set of messaging management services, including messaging, storing messages, uploading and downloading attachments, and managing recent contacts. It originally supports sending various types of messages, including text, audio, image, video, file, geographic location, reminder etc., and supports sending custom messages as well. For details of the messaging features, please refer to basic messaging features in the product introduction.

NIMMessageTypeMessage type

Enumeration	Value	Description
kNIMMessageTypeText	0	Text message
kNIMMessageTypekNIMMessageTypeImageText	1	Image message
kNIMMessageTypeAudio	2	Audio message
kNIMMessageTypeVideo	3	Video message
kNIMMessageTypeLocation	4	Location message
kNIMMessageTypeNotification	5	System notifications (including those for joining and exiting team, etc.,
kNIMMessageTypeFile	6	File message
kNIMMessageTypeTips	10	Reminder type message, content of which should be from the kNIMMsgKeyServerExt field in the message structure and filled in according to format requirements
kNIMMessageTypeRobot	11	and AI robot messages (not yet available)
kNIMMessageTypeCustom	100	Custom message
kNIMMessageTypeUnknown	1000	Unknown type of message, it is the default value

NIMMessageFeatureMessage type

Enumeration	Value	Description
kNIMMessageFeatureDefault	0	Default
kNIMMessageFeatureLeaveMsg	1	Offline message
kNIMMessageFeatureRoamMsg	2	Roaming message
kNIMMessageFeatureSyncMsg	3	Default messages, which are synchronized to each terminal upon multi-terminal login
kNIMMessageFeatureCustomizedMsg	4	Passthrough message

NIMIMMessageBasic message contents

Type	Parameter	Description
NIMSessionType	SessionType	Session type, for details please refer to NIMSessionType
string	SenderID	Sender ID, filled out by server, which the sender may ignore
string	ReceiverID	Receiver's id (required), which should be your own id when sending a message to yourself
NIMClientType	SenderClientType	Sender client type, filled out by server, which the sender may ignore
string	SenderDeviceId	Sender device id, filled out by server, which the sender may ignore
string	SenderNickname	Sender nickname, filled out by server, which the sender may ignore
long	TimeStamp	Message timestamp (13-digit UNIX timestamp in milliseconds)
NIMMessageType	MessageType	Message type, see NIMMessageType for details
string	ClientMsgID	Message uuid, unique identifier, to be completed by sender
string	ServerMsgId	Server-side message id, to be completed by server
string	ServerExtension	It is the third-party extension field and must be non-formative characters tring that can be parsed into json, with length limit 1024.
bool	ResendFlag	To resend message? Send for the first time:0, resend the message: 1
bool	NeedPush	If push is needed, 1: yes, 0: no
bool	NeedCounting	(Optional) Is counting needed for push message (corner mark), 1: yes, 0: no
bool	NeedPushNick	(Optional) Whether push messages need prefixes, set to true by default
string	PushContent	Custom push content, with a length not exceeding 200 bytes
JsonExtension	PushPayload	Custom push attributes, must be unformatted json string with a length limited to 2048
bool	ServerSaveHistory	(Optional) The message is once saved on the cloud? The default is 1, 1: yes, 0: no, if roaming and offline features are supported, then it must be set to 1
bool	Roaming	(Optional) Enable roaming for the message? The default is 1, 1: yes, 0: no
bool	MultiSync	(Optional) Enable multi-terminal sync for the message? The default is 1, 1: yes, 0: no
bool	Routable	(Optional) The message is copied? 0:no, 1:yes, follow app router configuration in default
bool	SavedOffline	(Optional) Save messages offline? The default is 1, 1: yes, 0: no, if roaming is supported, then it must be set to 1
bool	AntiSpamEnabled	Is Yidun anti-spam needed? 1: yes, 0: no
string	AntiSpamContent	(Optional) Anti-spam field customized by developer, length limit: 5000 characters, format: json string, {"type": 1: text, 2: image, 3 video, "data": "Text content or image address or video address"}
bool	ClientAntiSpamHitting	It determines to filter via the client anti-spam service. According to "Match with message filtering rules", if it is matched with relate rules, the value is "true", and the other party will not receive the message. It is mainly used for filtering sensitive words related to games.
string	AntiSpamBizID	(Optional) It is the extra anti-spam service ID that is configured for a single message by users (unavailable temporarily).
string	LocalFilePath	Local absolute path of multimedia message resource, managed by SDK locally and is required when sending multimedia messages. In case of image messages, when setting up thumbnail download, this path should be the local absolute path of the thumbnails
string	TalkID	Session id, optional for sender. The receiver receives the sender id
string	ResourceId	Session id, optional for sender. The receiver receives the client message id
NIMMsgLogStatus	MsgLogStatus	Local message status, see message status type for details)
NIMMsgLogSubStatus	MsgLogSubStatus	(Local message sub-status, see message sub-status type for details)
string	LocalExtension	Local extension contents, local storage only, reserved field

Note: Roaming means that the messages that have been received at one terminal will be delivered other offline clients (limited to the last 100 sessions on the server). Multi-terminal synchronization means that when multiple device platforms log in at the same time, a message sent by one terminal will be synchronously received by other terminals. Offline means if the receiver is offline when the message is sent, it can receive the message as soon as it goes online again.

Description of message settings:

	SavedOffline	ServerSaveHistory	Roaming	MultiSync
Offline message	1	1	optional	optional
Roaming message	1	1	1	optional
Multi-terminal message sync	optional	optional	optional	1

Send message

SDK supports common built-in messages types such as text, picture, voice, video, file, geographic location, reminder (NIMMessageType), as well as sending custom messages. At the same time, we also provide a stop sending interface, which is currently mainly used to stop sending file message that is being uploaded.

• API prototype

public static void SendMessage(NIMIMMessage message, ReportUploadProgressDelegate action = null);

• Parameter Description

Parameter	Description
message	For message content, see NIMIMMessage.
action	Notification of upload progress callback, which informs upload progress of self-uploaded attachments such as images, audio and video files (if any)

Message setting

The following message property settings (corresponding to the field in NIMIMMessageare also provided for sending messages:

• Messages can have two types of extension fields, namely server extension field kNIMMsgKeyServerExt and local extension field kNIMMsgKeyLocalExt, each with a maximum length of 1024 bytes. The server extension field will be sent to other terminals, while the local extension field is only valid locally. Both extension fields will be stored by the SDK in the database.

• Push text field (kNIMMsgKeyPushContent, with a maximum length of 200 bytes) and custom push attribute (kNIMMsgKeyPushPayload, with a maximum length of 2048 bytes), please pay attention to the maximum length. If push text is set, the text will be displayed in the notification bar when the message is received by the recipient, if not, then SDK's default text will be used.

• Whether push field is neededkNIMMsgKeyPushEnable, 0: not needed, 1: needed.

• Whether message count field is needed (kNIMMsgKeyNeedBadge), 0: not needed, 1: needed.

• Whether push nickname is needed (kNIMMsgKeyNeedPushNick), 0: not needed, 1: needed.

• Whether to store the message in the cloud (kNIMMsgKeyHistorySave), if it is set to 0, the message cannot be obtained by calling the interface of server message history. 0: Not needed, 1: Needed.

• Whether the message supports roaming (kNIMMsgKeyMsgRoaming). If it is set to 1, even if a certain client has received the message, other clients can still obtain it by roaming when they log in again. 0: Not needed, 1: Needed.

• Whether the message supports multi-terminal synchronization (kNIMMsgKeyMsgSync). If it is set to 1, a message sent will be synchronized to other clients logged in at the same time. 0: Not needed, 1: Needed.

Team messages have forced push attributes (can be used to implement @ features, etc.):

• Whether force push field (kNIMMsgKeyIsForcePush)is needed, 0: not needed, 1: needed.

• Force push list field (kNIMMsgKeyForcePushList), should be filled in with the specified account id string array json, and left empty if forced push is enabled for all.

• Text field (kNIMMsgKeyForcePushContent) in force push team message

Anti-spam field:

• The ID of the anti-spam rule specified by the developer for the message (kMsgTagAntiSpamBusinessId), should be the same as that on the server side

• Whether YiDun anti-spam is needed (kNIMMsgKeyAntiSpamEnable), 0: not needed, 1: needed.

• (Optional) Anti-spam field customized by developer (kNIMMsgKeyAntiSpamContent), length limit: 5000 characters, format: json string, {"type": 1: text, 2: image, 3 video, "data": "Text content or image address or video address"}

• Whether a single message uses YiDun anti-spam (kNIMMsgKeyAntiSpamUsingYiDun), 0: (YiDun activated) not passing YiDun anti-spam but general anti-spam, with all other matters still subject to original rules.

Text message

Create text message content, complete the necessary message setting and send the message through theSendMessageinterface.

NIMTextMessageText message

NIMTextMessage is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeText.
string	TextContent	Text content

• Example

//In case of p2p message and test account test1
NIMTextMessage msg = new NIMTextMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;
msg.TextContent = "This is a text message." ;

//Other message settings, same as above
msg.Roaming = true;
msg.SavedOffline = true;
msg.ServerSaveHistory = true;

//If anti-spam is needed
msg.AntiSpanEnabled = true;
//Assemble anti-spam content
JsonExtension jx = new JsonExtension();
jx.AddItem("type",1);
jx.AddItem("data",msg.TextContent);//If it is image or video type, attachment url shall be filled in.

msg.AntiSpamContent = jx.Value;
...

NIM.TalkAPI.SendMessage(msg,null);

Picture message

Create image message content, complete the necessary message setting and send the message through the SendMessage interface. The sent local image file will be automatically uploaded.

NIMTextMessageis derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeImage.
NIMImageAttachment	ImageAttachment	Content of image attachment

NIMMessageAttachmentFile attachment base class

Type	Parameter	Field
string	MD5	md5 of the file content
Int64	Size	File size, 64-bit integer
string	RemoteUrl	http url of the file
string	DisplayName	file name
string	FileExtension	File extension
string	LocalResID	Local file resource id, not required

The attachment content of an image message NIMImageAttachment is derived from NIMMessageAttachment, with field description.

Type	Parameter	Field
int	Width	Image width
int	Height	Image height

• Example

//In case of p2p message and test account test1
NIMImageMessage msg = new NIMImageMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//If a local file is sent, LocalFilePath shall be assigned.
msg.LocalFilePath="c：\\img.png";

//Assemble attachment content
NIMImageAttachment attachment = new NIMImageAttachment();
attachment.MD5 = "0ca175b9c0f726a831d895e269332461";
attachment.Size = 409600;
attachment.RemoteUrl="http://xxxxxx/img.png";//If local file is sent, the value is null.
attachment.DisplayName="img";
attachment.FileExtension="png";

//Set image height and width
attachment.Width = 800;
attachment.Height = 600;

msg.ImageAttachment = attachment;

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

Voice message

Create voice message content, complete the necessary message setting and send the message through theSendMessageinterface. The sent local audio file will be automatically uploaded.

NIMAudioMessage is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeAudio.
NIMAudioAttachment	AudioAttachment	Content of audio attachment

The attachment content of an audio message NIMAudioAttachment is derived fromNIMMessageAttachment, with field description.

Type	Parameter	Field
int	Duration	Audio message duration

• Example

//In case of p2p message and test account test1
NIMAudioMessage msg = new NIMAudioMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//If a local file is sent, LocalFilePath shall be assigned.
msg.LocalFilePath="c：\\audio.aac";

//Assemble attachment content
NIMAudioAttachment attachment = new NIMAudioAttachment();
attachment.MD5 = "0ca175b9c0f726a831d895e269332461";
attachment.Size = 409600;
attachment.RemoteUrl="http://xxxxxx/audio.aac";//If local file is sent, the value is null.
attachment.DisplayName="audio";
attachment.FileExtension="aac";

//Set the duration
attachment.Duration = 8000;//ms

msg.AudioAttachment = attachment;

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

Video message

Create video message content, complete the necessary message setting and send the message through the SendMessage interface. The sent local video file will be automatically uploaded.

NIMVideoMessage is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeVideo.
NIMVideoAttachment	VideoAttachment	Content of video attachment

The attachment content of a video message NIMVideoAttachment is derived fromNIMMessageAttachment, with field description.

Type	Parameter	Field
int	Duration	Audio message duration
int	Width	Image width
int	Height	Image height

• Example

//In case of p2p message and test account test1
NIMVideoMessage msg = new NIMVideoMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//If a local file is sent, LocalFilePath shall be assigned.
msg.LocalFilePath="c：\\video.mp4";

//Assemble attachment content
NIMVideoAttachment attachment = new NIMVideoAttachment();
attachment.MD5 = "0ca175b9c0f726a831d895e269332461";
attachment.Size = 409600;
attachment.RemoteUrl="http://xxxxxx/video.mp4";//If local file is sent, the value is null.
attachment.DisplayName="video";
attachment.FileExtension="mp4";

//Set video length and image length and width
attachment.Duration = 8000;//ms
attachment.Width = 800;
attachment.Height = 600;

msg.VideoAttachment = attachment;

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

Geographic location

Create location message content, complete the necessary message setting and send the message through the SendMessage interface.

NIMLocationMessageLocation message

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeLocation.
NIMLocationMsgInfo	LocationInfo	Content of geographical location attachment

The attachment contentNIMLocationMsgInfoof the location message contains description of

Type	Parameter	Field
string	Description	Location description
int	Latitude	Latitude
int	Longitude	Longitude

• Example

//In case of p2p message and test account test1
NIMLocationMessage msg = new NIMLocationMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//Assemble attachment content
NIMLocationMsgInfo attachment = new NIMLocationMsgInfo();

//Set location name, latitude and longitude
attachment.Description = "Hangzhou";
attachment.Latitude = 30.3;
attachment.Longitude = 120.2;

msg.LocationInfo = attachment;

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

File message

Create file message content, complete the necessary message setting and send the message through the SendMessage interface.

NIMFileMessage is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeFile.
NIMMessageAttachment	FileAttachment	For content of file attachment, see NIMMessageAttachment.

• Example

//In case of p2p message and test account test1
NIMVideoMessage msg = new NIMVideoMessage();
msg.ReceiverID = "test1";
msg.SessionType = NIMSessionType.kNIMSessionTypeP2P;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

msg.LocalFilePath="c：\\Document.doc";

//Assemble attachment content
NIMMessageAttachment attachment = new NIMMessageAttachment();
attachment.MD5 = "0ca175b9c0f726a831d895e269332461";
attachment.Size = 409600;
attachment.DisplayName="Document";
attachment.FileExtension="doc";

msg.FileAttachment = attachment;

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

Tip message

Create reminder message content, complete the necessary message setting and send the message through the SendMessage interface. If sending to server is not needed, the developer can use the insert local message to store the message in the database and update the session class table.

NIMTipMessageTip message

NIMTipMessage is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeTips.
string	TextContent	Text content
string	Attachment	It is the content of message tip attachment, with custom json character string, and used for independent parsing and application.

• Example

//The team message is taken as an example. The test team id is 122222.
NIMTipMessage msg = new NIMTipMessage();
msg.ReceiverID = "122222";
msg.SessionType = NIMSessionType.kNIMSessionTypeTeam;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//Assemble attachment content
msg.TextContent = "This is a message tip."
msg.Attachment = "attachment";//It is custom attachment content and used for independent parsing.

//Other message settings
...

Method 1:
//Send a message to the other party
NIM.TalkAPI.SendMessage(msg,null);

Method 2:
//If it is inserted locally, instead of being sent to the other party, the interface for inserting message history shall be used.
NIM.Messagelog.MessagelogAPI.WriteMsglog("122222",true, msg, (code, msgId)=>
{
	...
});

Custom message

Create custom message content, complete the necessary message setting and send the message through the SendMessage interface. SDK will not parse the specific content of custom messages, and the corresponding work should be assumed by the developer. SDK will save custom message to message database, which will be shown in message history together with built-in message.

NIMCustomMessageCustom message

NIMCustomMessage<T> is derived from NIMIMMessage and will succeed all father-class fields.

Type	Parameter	Field
NIMMessageType	MessageType	It is designated as NIMMessageType.kNIMMessageTypeCustom.
string	Extention	Text content
T	CustomContent	It is the content of custom message tip attachment, with custom json character string, and used for independent parsing and application. T is custom object that can be serialized into json, and succeeded from NimJsonObject.

• Example

//Define custom class independently
public class CustomMessageAttachment:NimJsonObject<CustomMessageAttachment>
{
	//Custom field 1
 	[JsonProperty("customFiled1")]
	public string customFiled1 {set;get;}

	//Custom field 2
    [JsonProperty("customFiled2")]
	public int customFiled2 {set;get;}
}

//The team message is taken as an example. The test team id is 122222.
NIMCustomMessage<CustomMessageAttachment> msg = new NIMCustomMessage<CustomMessageAttachment>();
msg.ReceiverID = "122222";
msg.SessionType = NIMSessionType.kNIMSessionTypeTeam;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;

//Assemble attachment content
CustomMessageAttachment attachment = new CustomMessageAttachment();
attachment.customFiled1 = "Custom content";
attachment.customFiled2 = 10;


msg.Extention = "Content of custom message";
msg.CustomContent = attachment;//Custom attachment content, for independent parsing.

//Other message settings
...

NIM.TalkAPI.SendMessage(msg,null);

Team force push message

Send force push message to a team, and @ designated members or all members

TeamForecePushMessageParameter description

Type	Parameter	Description
List	ReceiverList	Set of account ids of @ members for force push
bool	IsForcePush	It determines to force push.
string	Content	Content of force push

• API prototype

public static void SendTeamFrocePushMessage(NIMIMMessage message, TeamForecePushMessage forceMsg, ReportUploadProgressDelegate action = null);

• Parameter Description

Parameter	Description
message	For message content, see "Send messages.
forceMsg	For settings of force push message, see TeamForcePushMessage
action	It is the notification of callback for uploading files, and the message for automatic upload is not required. The value is null.

• Example

//The team message is taken as an example. The test team id is 1222222.
NIMTextMessage msg = new NIMTextMessage();
msg.ReceiverID = "1222222";
msg.SessionType = NIMSessionType.kNIMSessionTypeTeam;
msg.TimeStamp=1520500638234;//Current UNIX timestamp, unit: ms
msg.ClientMsgID = "uuid";//Generate my unique uuid;
msg.TextContent = "This is a text message." ;

//Other message settings
...

//Force push to team members test1, test2
TeamForecePushMessage forePush = new TeamForecePushMessage();
forePush.IsForcePush = true;
forePush.ReceiverList = new List<string>();
forePush.ReceiverList.add("test1");
forePush.ReceiverList.add("test2");
forePush.Content = "This is a force push message";

NIM.TalkAPI.SendTeamFrocePushMessage(msg,forePush,null);

Sending result notification

Sending is successful or failed, and the result also contains tag (if any) for client anti-spam hit.

MessageAckParameter description

Type	Parameter	Description
string	TalkId	Session ID
string	MsgId	Message id
ResponseCode	Response	Error code
bool	ClientAntiSpam	Is there a hit with client anti-spam, 1: Yes, 0: No

• API prototype

void OnSendMessageResult(object sender,MessageArcEventArgs args)
{
	....
}

//Monitor event
NIM.TalkAPI.OnSendMessageCompleted += OnSendMessageResult;

//Cancel monitoring
NIM.TalkAPI.OnSendMessageCompleted -= OnSendMessageResult;

Stop sending message

Stop sending message. Currently it only can be used on file messages, meaning sending can be terminated during file upload. It can't be used on a file that has already been uploaded.

• API prototype

 public static void StopSendMessage(NIMIMMessage message, ReportUploadProgressDelegate action = null);

• Parameter Description

Parameter	Description
message	Structure of the message to be stopped
action	Reserved, not in use for now

• Example

//Current available file type, required
NIMIMMessage msg = new NIMIMMessage();
msg.MessageType = NIMMessageType.kNIMMessageTypeFile;
msg.ClientMsgID = "uuid";//Unique uuid of the message to be stopped, required

//Interrupt sending
NIM.TalkAPI.StopSendMessage(msg,null);

Receive message

The developer needs to register the event monitoring of message reception before logging in to the SDK. Message receiving covers online, offline, synchronized, roaming messages, etc. If a multimedia message is received, the SDK will automatically download attachments in the background by default. In case of voice message, the audio file will be downloaded directly. In case of image message, only the thumbnail will be downloaded, and you can get the original image through the download interface.

NIMReceivedMessageParameter description

Type	Parameter	Description
ResponseCode	ResponseCode	Error code
NIMIMMessage	MessageContent	For message content, see NIMIMMessage. Different message types have different definitions. Refer to Send messages.
NIMMessageFeature	Feature	See NIMMessageFeature
TeamForecePushMessage	TeamPushMsg	For content of team forced push message, see TeamForecePushMessage

1.Receive messages online

• API prototype

public static EventHandler<NIMReceiveMessageEventArgs> OnReceiveMessageHandler;

• Example

void OnMessageReceived(object sender,MessageArcEventArgs args)
{
	if (args != null && args.Message != null) {

		//Process various types of messages
        if (args.Message.MessageContent.MessageType == NIMMessageType.kNIMMessageTypeText) {
			...
        }
        else if (args.Message.MessageContent.MessageType == NIMMessageType.kNIMMessageTypeAudio) {
            ...
        }
        else if (args.Message.MessageContent.MessageType == NIMMessageType.kNIMMessageTypeVideo) {
            ...
        }
        else if (args.Message.MessageContent.MessageType == NIMMessageType.kNIMMessageTypeImage)
        {
        	...
        }
        else
        {
        	...
        }
	}
	....
}

//Monitor event
NIM.TalkAPI.OnReceiveMessageHandler += OnMessageReceived;

//Cancel monitoring
NIM.TalkAPI.OnReceiveMessageHandler -= OnMessageReceived;

2. Receive offline synchronized roaming message

Receive batch messages, such as offline, roaming, and synchronized bulk messages. If this batch interface is also registered while registering receive message callback, when there are incoming batch messages, this interface will be used to notify the application. For example, for offline messages received after logging in, etc., the event monitoring must be registered before logging in.

• API prototype

public static void RegReceiveBatchMessagesCb(ReceiveBatchMesaagesDelegate cb)

• Parameter Description

Parameter	Description
cb	Callback of batch messages

• Example

void OnBatchMessagesReceived(List<NIMReceivedMessage> msgsList)
{
	if (msgsList != null)
    {
    	//Enumerate array, process messages
    	foreach (NIMReceivedMessage v in msgsList)
        {
        	....
        }
    }
}

//Monitor event
NIM.TalkAPI.RegReceiveBatchMessagesCb(OnBatchMessagesReceived);

//Cancel monitoring
NIM.TalkAPI.RegReceiveBatchMessagesCb(null);

3. Filter team notification message

Register the callback for whether filtering incoming team notifications. If this callback returns true, the SDK deems the notification as processed, therefore it will not deliver it through the receive message channel, and will not save it to the local database.

• API prototype

public static void RegTeamNotificationFilterCb(TeamNotificationFilterDelegate action);

• Parameter Description

Parameter	Description
action	Callback for filtering team notifications

• Example

bool OnTeamNotificationFiltered(NIMIMMessage msg,string jsonExtension)
{
	if (msg == null)
       return false;
	...

   	//If a notification message is processed and filtered, "true" will be returned; otherwise, "false" will be returned.
    return true;
}

//Monitor event
NIM.TalkAPI.RegTeamNotificationFilterCb(OnBatchMessagesReceived);

//Cancel monitoring
NIM.TalkAPI.RegTeamNotificationFilterCb(null);

Forward message

The user gets a new message object via construction API, and then calls the message sending interface.

• API prototype

public static NIMIMMessage CreateRetweetMessage(NIMIMMessage srcMsg, NIMMessageSetting msgSetting, string msgId, string sessionId, Session.NIMSessionType sessionType, long timetag);

• Parameter Description

Parameter	Description
srcMsg	Received message content. For the content, see NIMIMMessage.
msgSetting	Message setting, for details, please refer to message setting description
msgId	New message uuid generated
sessionId	The other party's id, forwarded, user account or team id
sessionType	Session type, 0: p2p message 1: team message
timetag	Current timestamp (in milliseconds)s

• Example

//Assume srcMsg being the message body that has been sent or received.
NIMIMMessage srcMsg;

//Message settings, to be configured as needed
NIMMessageSetting msgSetting = new NIMMessageSetting();
msgSettting.ServerSaveHistory = true;
...

//A new message generated through srcMsg.
long timeNow = 1520500638234;//Current UNIX timestamp, unit: ms
string sessionid = "1222222";
string clientMsgID = "uuid2";//A generated new unique uuid;
NIMSessionType sessionType = NIMSessionType.kNIMSessionTypeTeam;
NIMIMMessage newMsg = NIM.TalkAPI.CreateRetweetMessage(srcMsg,msgSettting,clientMsgID,sessionid,sessionType,timeNow);

NIM.TalkAPI.SendMessage(newMsg,null);

Recall message

Sender, team owner and manager can perform recall through this interface (not applicable to chat room messages). This operation is generally time-limited (subject to global APP settings), and 508 is returned if the limit is exceeded. By registering callback notification for message recall, the developer receives notifications of message recalls on other clients. After receiving the notification, the SDK will mark the message as deleted in the message history. At the same time, the developer deletes the message displayed on the interface and can even insert a corresponding prompt if needed. For related development examples, refer to IM Demo.

RecallNotificationParameter description

Type	Parameter	Description
NIMSessionType	SessionType	Session type, 0: p2p message 1: team message
string	SenderId	Message from ID
string	ReceiverId	Message to ID
string	MsgId	Unique id of the message
string	NOtify	Custom notification copy
long	Timetag	Timestamp of recall operation (in milliseconds)s
NIMMessageFeature	Feature	Type of the recalled message, see NIMMessageFeature for details
bool	MsgLocalExist	Whether the recalled message exists locally. For example, if the other party sent and recalled a message while offline, then the other party gets an offline recall notification after going online, the tag should be false
long	MsgTimetag	Timestamp of recalled message, unit: ms
string	Nickname	Nickname of the sender of the message to be recalled
string	Operator	Operator ID

Active message recall

To recall messages that have been sent successfully, which relies on local history. It is required to find the message in local history according to its message id, if not the message can't be recalled.

• API prototype

public static void RecallMessage(string msgId, string notify, RecallMessageDelegate cb);

• Parameter Description

Parameter	Description
msgId	Uuid of the message to be recalled
notify	Custom notification
cb	Callback notification of message recall

• Example

//Assume msgId is the id of the message that has been sent.
NIM.TalkAPI.RecallMessage(msgId,"This is a recall notify",(result, notify)=>{
	...
});

Message recall notification

Notify the user that the message has been recalled, this notification is available offline.

• API prototype

public static void RegRecallMessageCallback(RecallMessageDelegate cb);

• Parameter Description

Parameter	Description
action	Callback of message recall notification

• Example

void OnRecallMsgResult(ResponseCode result, RecallNotification[] notify)
{
	//Processing interface
	....
}

//Monitor event
NIM.TalkAPI.RegRecallMessageCallback(OnRecallMsgResult);

//Cancel monitoring
NIM.TalkAPI.RegRecallMessageCallback(null);

---

Read receipt

CommsEase provides read receipts of point-to-point messages. Note: This feature is only valid for P2P messages.

In the session interface, the operation of calling the interface for sending the read receipt and inputting the last message means that all the previous messages have been read, and the other side will receive the receipt.

General application scenarios for sending message read receipts:

1. Entering P2P chat interface (if you repeatedly enters the interface without receiving a new message, SDK can automatically filter repeated interface calls, so that only one of them is sent to the CommsEase server).

2. When you are in the chat interface and receive a new message from the current session.

Send read receipt

• API prototype

 public static void SendReceipt(NIMIMMessage msg, MsglogStatusChangedDelegate cb, string jsonExtension = null);

• Parameter Description

Parameter	Description
msg	Message content received
cb	The callback notification of message status change after sending the message read receipt
jsonExtension	Extension field. Reserved

• Example

//Assuming msg is a message that requires sending read receipt.
NIM.Messagelog.MessagelogAPI.SendReceipt(msg,(res,result)=>{
	//Result - json character string, example: [{"talk_id":"test1","msg_timetag":"1520500638234","status":2}]
    ...
},null);

Monitor read receipt notification

Read receipt also represents a change in message status and therefore can be reflected in global message status change notification

Monitor broadcast to all notifications

Receive broadcast to all notifications. There are two types: individual and batch broadcast to all notifications. In general, batch notifications include offline broadcasts, synchronous broadcasts, and roaming broadcasts delivered when logging in.

NIMBroadcastMessageDescription of broadcast notification parameters

Type	Parameter	Description
long	MsgID	Notification message id
string	Sender	Sender account, can be null
long	Timetag	Notification message's UNIX timestamp, in milliseconds
string	Body	Notification content

1. Callback for receiving Individual broadcast to all notification , recommended to register it globally, so that messages can be distributed to specific sessions after accepting callbacks as a whole.

• API prototype

 public static void RegReceiveBroadcastCb(ReceiveBroadcastDelegate cb);

• Parameter Description

Parameter	Description
cb	Notification callback

• Example

void OnReceiveBroadcastMsg(NIMBroadcastMessage msgs)
{
	//Process broadcast notification
	...
}

//Monitor event
NIM.TalkAPI.RegReceiveBroadcastCb += OnReceiveBroadcastMsg;

//Cancel monitoring
NIM.TalkAPI.RegReceiveBroadcastCb -= OnReceiveBroadcastMsg;

2. Batch broadcast to all notifications

Callback for receiving batch broadcast messages. If this batch interface is also registered while registering receive message callback, when there are incoming batch messages, including offline messages received after logging in, this interface will be used to notify the application.

• API prototype

public static void RegReceiveBroadcastMsgsCb(ReceiveBroadcastMsgsDelegate cb);

• Parameter Description

Parameter	Description
cb	Callback of batch messages

• Example

void OnReceiveBroadcastMsgs(List<NIMBroadcastMessage> msgs)
{
	if (msgs != null)
    {
    	//Enumerate array, process broadcast
    	foreach (var v in msgs)
        {
        	....
        }
    }
}

//Monitor event
NIM.TalkAPI.RegReceiveBroadcastMsgsCb(OnReceiveBroadcastMsgs);

//Cancel monitoring
NIM.TalkAPI.RegReceiveBroadcastMsgsCb(null);

Get local path from message attachment

Get local paths of message attachments (image, voice, video, etc.). If pre-loaded only thumbnails without downloading the original images, files in the path obtained here may not exist, and the developer needs download them by callingnim.Nos.NosAPI.DownloadMedia. If thumbnail is preloaded according to global setting and the original image is needed, then before passing in the message content, the fieldLocalFilePathshould be set to blank or a custom save path.

• API prototype

public static string GetAttachmentPathFromMsg(NIMIMMessage msg);

• Parameter Description

Parameter	Description
msg	Message content to be obtained

• Example

//Assuming msg is a message to be obtained
string filePath = NIM.Talk.TalkAPI.GetAttachmentPathFromMsg(msg);

//Download original image
msg.LocalFilePath = null; //It is null, or set to custom save path;
nim.Nos.NosAPI.DownloadMedia (msg, (rescode, filePath, callId, resId)=>
{
	//Notification completed
	...
},
(prgData)=>
{
    //Notification progress
    ...
});

Get image thumbnail

In default, after receiving an image message, CommsEase PC SDK will pre-load the original image and put it into the local cache. If you want to control the quality of downloaded images, you can do so by configuringkNIMPreloadImageQuality(for quality control) andkNIMPreloadImageResize(for size control) when initializing the SDK. The IM Demo's development example downloads original images by default. Therefore, in case of development using source codes of IM Demo, you need to download the original images for image preview or other links that need to use original images.

In scenes including but not limited to the following, developers can download thumbnails by themselves:

• There are special requirements on image size
• Received picture messages in chat room

Currently SDK provides two schemes for obtaining thumbnails:

• To update image quality

  After receiving the image message, the user can obtain the download address of the image by parsing the content of attachmentkNIMMsgKeyAttach(kNIMChatRoomMsgKeyAttachif chat room message), and then obtain the image of specified quality based on parameters for splicing download interface: Download address is http(s)://?imageView&quality=N; http(s)://xxx; where N is image quality, with a range of 0 to 100.

• The image is intra-shrunk by length and width (in proportion to the original size, with the obtained image having "one side of the requested length, and the other of less than or equal to the requested length")

  After receiving an image message, users can obtain the download address of the image by parsing the content of attachment kNIMMsgKeyAttach (kNIMChatRoomMsgKeyAttach if chat room message), and then obtain the thumbnail based on parameters for splicing download interface: http(s)://xxx?imageView&thumbnail=XxY; http(s)://xxx is the image download address; where X is the width, Y is the height, and the middle symbol is the lowercase x. The value of width and height vary within the range of 0-4096.

  Variations of several parameters: 1. XxY: general (intra) shrink 2. Xx0: fixed width and adaptive height (intra shrink) 3. 0xY: fixed height and adaptive width (intra shrink)

Currently in IM Demo project, images displayed in messages are all compressed, for details refer to bubble_image.cpp