Messaging

Messaging in the mobile world can take several forms: SMS (text), Picture Messaging (text and graphics), smart messaging (short messages holding content such as ringtones and notifications), and MMS (digital image input) can be sent with the mobile device. Note that not all these are available in all devices.

The Wireless Messaging API (JSR-205) specification allows you to compose, send, and receive SMS, MMS, and CBS messages through Java™ applications (MIDlets).

The Wireless Messaging API (WM API) is based on the Generic Connection Framework (GCF). The GCF is defined in the javax.microedition.io package of the Connected Limited Device Configuration (CLDC) 1.0 specification. The package defines an extensible framework for connections and supports input/output and networking functionality in Java Platform Micro Edition profiles.

Representation of a message

A message can be thought of as having an address part and a data part. A message is represented by a class that implements the interface defined for messages in the WM API 2.0. This interface provides methods that are common for all messages. In the javax.wireless.messaging package, the base interface that is implemented by all messages is named Message. It provides methods for addresses and timestamps.

For the data part of the message, the WM API 2.0 is designed to handle text, binary and multipart messages. These are represented by three subinterfaces of Message: TextMessage, BinaryMessage and MultipartMessage. These subinterfaces provide ways to manipulate the payload of the message as Strings, byte arrays and message parts, respectively.

Other subinterfaces of Message can be defined for message payloads which are neither pure text nor pure binary. It is also possible to create further subinterfaces of TextMessage, BinaryMessage and MultipartMessage for possible protocol-specific features.

Sending and receiving messages

As defined by the Generic Connection Framework, the message sending and receiving functionality is implemented by a Connection interface, in WM API 2.0's case, MessageConnection. To make a connection, the application obtains an object implementing the MessageConnection from the Connector class by providing a URL connection string that identifies the address.

For more information about the sending and receiving of messages, see the Wireless Messaging API (JSR-205) specification.

Permissions for Series 40 and Symbian MIDP 2.0 Platforms

When the WM API 2.0 interfaces are deployed on a Series 40 and Symbian MIDP 2.0 device, permissions must be granted to open a connection and to send and receive messages. Separate permissions are provided for the SMS and CBS protocols.

To open a connection, a MIDlet suite must have the appropriate permission to access the MessageConnection implementation. If the permission is not granted, then Connector.open must throw a SecurityException. To send and receive messages, the MIDlet suite can restrict certain types of messages or connection addresses. If the application attempts to send or receive either a restricted type of message or a message with a restricted connection address, then a SecurityException must be thrown.

For more information about the permissions in WM API 2.0, see Appendix E of Wireless Messaging API (JSR-205) specification.