sorry, dulu pernah mampir di blogku ya nanyain tentang cmss. nih semoga bermanfaat: Introduction
CMSS stands for Computer Message Switching System. Its primary functions are: • Send and receive meteorological messages and files (for example, charts). • Produce bulletins (or collectives) of meteorological reports in accordance with WMO/GTS rules. • Interface to message Decoders to allow data to be decoded, plotted, fed into numerical models etc • Allow local messages to be manually entered • Provide a comprehensive Graphical User Interface (GUI) to allow the operators to be alerted about significant events (for example, coding errors in msgs), control the communications lines etc
Data Flow In CMSS messages and details about messages are stored in large circular files. These circular files are of a fixed size so the storage capacity in CMSS is based on the number of messages and not on time (for example CMSS could be configured to hold 100,000 incoming messages but not to hold 24 hours of data). The reason for this is because we do not want to fill the computer disk(s) if there is a sudden increase in the number of messages received. Messages are passed between various CMSS processes via these circular files which can be written to by multiple processes but typically read by only one process. The basic CMSS data flow is as follows: 1. Incoming messages are written, by the Line Drivers, to a large circular file called msgintxt. 2. The msganal process reads the new messages from msgintxt and does the following: • Validate the message header and trailer. • Sends requests for missing messages based on breaks in sequence numbers • Checks for duplicate messages • Constructs a “directory” record (or summary record) about the message containing information such as time of receipt, TTAAII, CCCC etc. 3. Finally msganal writes the directory record to a circular file called MSGIN (short for Message In) 4. The message recognition process recogn reads new messages from MSGIN and does the following: • Finds each report within a message • Checks if the report is syntactically correct and if not then produces an alarm message. • Finds the station number and identifies the report type • Checks if the report is required for international bulletin production. • For each report it finds recogn writes a directory record to the REPORTS file that includes details such as the station number and report type. 5. After recognition, recogn, writes directory records for each report, and for the original message, to another circular file called switchdir 6. Another process, msgswtch, read the switchdir file and determines where each report or message is to be switched. Msgswtch queues messages to the required output circuits by adding them to the OUTQ (output queue) file. • The switching requirements are determined from a series of Database Switching Tables. There is one table for switching on WMO TTAAII, CCCC and another for switching on station number etc. • Normally all reports are automatically queued to the character decoder. 7. Associated with every output queue are two processes – a message preparation process (msgprep) and a Line Driver. 8. When a new message is placed on an output queue (OUTQ file) it is immediately read by the msgprep for that output line. Msgprep adds the required output header and trailer to the message and passes it to the output Line Driver. 9. Line Drivers send messages to the various destinations. There are different line driver processes for each different protocol eg X.25, TCP/IP sockets, FTP
1 komentar:
sorry, dulu pernah mampir di blogku ya nanyain tentang cmss.
nih semoga bermanfaat:
Introduction
CMSS stands for Computer Message Switching System.
Its primary functions are:
• Send and receive meteorological messages and files (for example, charts).
• Produce bulletins (or collectives) of meteorological reports in accordance with WMO/GTS rules.
• Interface to message Decoders to allow data to be decoded, plotted, fed into numerical models etc
• Allow local messages to be manually entered
• Provide a comprehensive Graphical User Interface (GUI) to allow the operators to be alerted about significant events (for example, coding errors in msgs), control the communications lines etc
Data Flow
In CMSS messages and details about messages are stored in large circular files. These circular files are of a fixed size so the storage capacity in CMSS is based on the number of messages and not on time (for example CMSS could be configured to hold 100,000 incoming messages but not to hold 24 hours of data). The reason for this is because we do not want to fill the computer disk(s) if there is a sudden increase in the number of messages received.
Messages are passed between various CMSS processes via these circular files which can be written to by multiple processes but typically read by only one process.
The basic CMSS data flow is as follows:
1. Incoming messages are written, by the Line Drivers, to a large circular file called msgintxt.
2. The msganal process reads the new messages from msgintxt and does the following:
• Validate the message header and trailer.
• Sends requests for missing messages based on breaks in sequence numbers
• Checks for duplicate messages
• Constructs a “directory” record (or summary record) about the message containing information such as time of receipt, TTAAII, CCCC etc.
3. Finally msganal writes the directory record to a circular file called MSGIN (short for Message In)
4. The message recognition process recogn reads new messages from MSGIN and does the following:
• Finds each report within a message
• Checks if the report is syntactically correct and if not then produces an alarm message.
• Finds the station number and identifies the report type
• Checks if the report is required for international bulletin production.
• For each report it finds recogn writes a directory record to the REPORTS file that includes details such as the station number and report type.
5. After recognition, recogn, writes directory records for each report, and for the original message, to another circular file called switchdir
6. Another process, msgswtch, read the switchdir file and determines where each report or message is to be switched. Msgswtch queues messages to the required output circuits by adding them to the OUTQ (output queue) file.
• The switching requirements are determined from a series of Database Switching Tables. There is one table for switching on WMO TTAAII, CCCC and another for switching on station number etc.
• Normally all reports are automatically queued to the character decoder.
7. Associated with every output queue are two processes – a message preparation process (msgprep) and a Line Driver.
8. When a new message is placed on an output queue (OUTQ file) it is immediately read by the msgprep for that output line. Msgprep adds the required output header and trailer to the message and passes it to the output Line Driver.
9. Line Drivers send messages to the various destinations. There are different line driver processes for each different protocol eg X.25, TCP/IP sockets, FTP
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