J2ME applications powered by wireless messaging have a platform-independent access to wireless communication resources like Short Message Service (SMS) and Cell Broadcast Service (CBS) for Global System for Mobile Communication (GSM) Networks.
Short Message Service (SMS)
SMS is the transmission of short text messages to and from a mobile phone, fax machine, and/or IP address in a GSM network. Messages must be no longer than 160 alphanumeric characters and contain no images or graphics. The main features of this service are speed, cheap rates, and the guarantee that the message will reach the target person, even if he is out of radio coverage or his phone is turned off.
Once a message is sent, it is received by a Short Message Service Center (SMSC), which must then get it to the appropriate mobile device. To do this, the SMSC sends a SMS request to the home location register (HLR) to find the roaming customer. Once the HLR receives the request, it will respond to the SMSC with the subscriber's status, as in 1) inactive or active, and 2) roaming location.
If the response is inactive, then the SMSC will hold onto the message for a period of time. When the subscriber accesses his device, the HLR sends a SMS notification to the SMSC, and the SMSC attempts delivery.
The SMSC transfers the message to a GSM message delivery system in a Short Message Delivery Point-to-Point format. The system pages the device and, if it responds, delivers the message.
The SMSC receives verification that the message was received by the end user, and then categorizes the message as sent and will not attempt to send it again. The SMS delivery mechanism is show in figure below
Cell Broadcast Service(CBS)
Cell Broadcast Service allows messages to be sent to every Mobile Station (MS), such as a mobile phone, fax machine, and/or IP address currently in a particular cell. Cell broadcast messages are repeated at intervals over a period of time, which allows an MS to receive the message even if entering the cell after the first transmission. The data can be sent either as binary data or ASCII text up to 15 pages in length, with a page being up to 93 characters in length; the test set only provides support for ASCII messages. Cell broadcast messages are classified by topic and allocated a channel number, message code, update number, and language:
A Channel Number is a header number identifying the message topic (such as 'Weather Report' or 'Traffic Information').
A Message Code identifies a particular message, so that an MS receiving a message with the same code as a previously received message will recognize that it is a repeat, and may not display it to the user.
An Update Number is used to identify a particular version of a message. This is useful for reporting a dynamic situation, where a message may be reporting one event (such as road construction ahead), but the details of which change periodically (the length of the traffic jam, for example). An MS that remains in one cell for a length of time will receive messages with the same message code, but update numbers as updated versions of the same message are received; however, an MS that enters the cell will receive only the most recent version of the message, followed by any subsequent versions.
Language indicates in what language the message is. Changing this parameter does not translate the text of a message.
While SMS is a one-to-one and one-to-few messaging system, CBS provides one-to-many messaging within a certain geographical area.
Workable model of Wireless Messaging System
This system can be viewed as a 3-tiered architecture, consisting of the Interface Layer, Implementation Layer and Transport Layer.
The Interface Layer constitutes a generic set of messaging interfaces, independent of any messaging protocol. These interfaces provide the basic definition of a message, define the basic functionality of sending and receiving it, and provide a mechanism for the MIDlet application to be notified of the incoming message.
The Implementation Layer contains classes which implement each Interface Layer to access wireless messaging like SMS or CBS functionalities on a GSM mobile device. For instance, from the SMS point of view, this layer provides an implementation of the message connection for SMS messages as well as an implementation of a SMS message with text or binary attributes. The Implementation Layer also performs segmentation and concatenation of messages for the underlying protocol. The MIDlet can then specify the number of segments a message should be broken into in a MessageConnection.
The Transport Layer contains classes that are the actual implementation of protocols that carry messages to the mobile device.
Short Message Service (SMS)
SMS is the transmission of short text messages to and from a mobile phone, fax machine, and/or IP address in a GSM network. Messages must be no longer than 160 alphanumeric characters and contain no images or graphics. The main features of this service are speed, cheap rates, and the guarantee that the message will reach the target person, even if he is out of radio coverage or his phone is turned off.
Once a message is sent, it is received by a Short Message Service Center (SMSC), which must then get it to the appropriate mobile device. To do this, the SMSC sends a SMS request to the home location register (HLR) to find the roaming customer. Once the HLR receives the request, it will respond to the SMSC with the subscriber's status, as in 1) inactive or active, and 2) roaming location.
If the response is inactive, then the SMSC will hold onto the message for a period of time. When the subscriber accesses his device, the HLR sends a SMS notification to the SMSC, and the SMSC attempts delivery.
The SMSC transfers the message to a GSM message delivery system in a Short Message Delivery Point-to-Point format. The system pages the device and, if it responds, delivers the message.
The SMSC receives verification that the message was received by the end user, and then categorizes the message as sent and will not attempt to send it again. The SMS delivery mechanism is show in figure below
Cell Broadcast Service(CBS)
Cell Broadcast Service allows messages to be sent to every Mobile Station (MS), such as a mobile phone, fax machine, and/or IP address currently in a particular cell. Cell broadcast messages are repeated at intervals over a period of time, which allows an MS to receive the message even if entering the cell after the first transmission. The data can be sent either as binary data or ASCII text up to 15 pages in length, with a page being up to 93 characters in length; the test set only provides support for ASCII messages. Cell broadcast messages are classified by topic and allocated a channel number, message code, update number, and language:
A Channel Number is a header number identifying the message topic (such as 'Weather Report' or 'Traffic Information').
A Message Code identifies a particular message, so that an MS receiving a message with the same code as a previously received message will recognize that it is a repeat, and may not display it to the user.
An Update Number is used to identify a particular version of a message. This is useful for reporting a dynamic situation, where a message may be reporting one event (such as road construction ahead), but the details of which change periodically (the length of the traffic jam, for example). An MS that remains in one cell for a length of time will receive messages with the same message code, but update numbers as updated versions of the same message are received; however, an MS that enters the cell will receive only the most recent version of the message, followed by any subsequent versions.
Language indicates in what language the message is. Changing this parameter does not translate the text of a message.
While SMS is a one-to-one and one-to-few messaging system, CBS provides one-to-many messaging within a certain geographical area.
Workable model of Wireless Messaging System
This system can be viewed as a 3-tiered architecture, consisting of the Interface Layer, Implementation Layer and Transport Layer.
The Interface Layer constitutes a generic set of messaging interfaces, independent of any messaging protocol. These interfaces provide the basic definition of a message, define the basic functionality of sending and receiving it, and provide a mechanism for the MIDlet application to be notified of the incoming message.
The Implementation Layer contains classes which implement each Interface Layer to access wireless messaging like SMS or CBS functionalities on a GSM mobile device. For instance, from the SMS point of view, this layer provides an implementation of the message connection for SMS messages as well as an implementation of a SMS message with text or binary attributes. The Implementation Layer also performs segmentation and concatenation of messages for the underlying protocol. The MIDlet can then specify the number of segments a message should be broken into in a MessageConnection.
The Transport Layer contains classes that are the actual implementation of protocols that carry messages to the mobile device.
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