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STOMP 1.2
GETTING THE MESSAGE ACROSS:
REBOOTED
BRIEF INTRODUCTION
• Julian Lyndon-Smith, IT Director dot.r limited
• Progress developer since v3, 1987
• Living proof of “old dog, new tricks”
• Often hanging around on PEG and PSDN
• Always up for a good argument ;)
WHY MESSAGING ?
• In-application
• Inter process
• Lan
• Wan
• Internet
WHAT’S WRONG WITH …
• Pub / sub
• Sonic
• IP/Works
• Zero MQ
• MO/SMS
WHAT’S NEEDED
• Message server
• Clients connect to server, like 4GL clients to db server
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•
•
•
Free / open source
Portable
Easy to set up and admin
Usable from the 4GL
WHAT’S AVAILABLE
• Apache Apollo
• HornetMQ
• RabbitMQ
• MorbidMQ
• Apache ActiveMQ
WE CHOSE …
• Apache ActiveMQ
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•
•
•
•
•
http://activemq.apache.org
Fusesource used to be a division of Psc
Fits all the criteria
Queues
Topics
wildcards
WHAT PROTOCOL ?
• Openwire
• REST
• Stomp
• XMPP
• AMQP
ENTER STOMP
“STOMP provides an interoperable wire format so
that STOMP clients can communicate with any
STOMP message broker to provide easy and
widespread messaging interoperability among many
languages, platforms and brokers.”
ENTER STOMP
• Simple Text-Orientated Messaging Protocol
• Stomp.github.com
• Text-based
• Therefore easy to use in the 4GL 
• Multiple clients
• Java, .net, javascript, php, ruby …
STOMP PROTOCOL
• Each message is sent within a “Frame”
COMMAND
Header1:value
Header2:value
Body^@
STOMP PROTOCOL
• Frame starts with command string<EOL>
• Followed by zero or more headers
• Each header consists of <key>:<value><EOL>
• Blank line indicates end of headers
• The body is terminated with a null ( chr(0) )
STOMP PROTOCOL
• All commands and headers are in UTF-8
• As mentioned, the body is terminated with chr(0)
• Unless you have a content-length:n header
• Which then means the body is read for n octets
• Regardless of embedded nulls
CONNECTING
• Client initiates connection by sending a CONNECT
frame
CONNECT
accept-version:1.2
host:stomp.github.org
^@
CONNECTED
• Server responds with a CONNECTED frame
CONNECTED
version:1.2
^@
SENDING MESSAGES
• Client sends messages by sending a SEND frame to
a destination
• Queue
• Topic
SENDING MESSAGES
SEND
destination:/queue/a
content-type:text/plain
hello queue a
^@
SENDING MESSAGES
SEND
destination:/topic/b
content-type:text/plain
hello topic b
^@
RECEIVING MESSAGES
• Client receives messages by sending a SUBSCRIBE
frame
• Queue
• Topic
• Wildcards
RECEIVING MESSAGES
• Client receives messages by sending a SUBSCRIBE
frame
• Waits for a message to arrive on the socket
• Data is parsed by the 4GL
RECEIVING MESSAGES
SUBSCRIBE
id:0
destination:/queue/foo
^@
RECEIVING MESSAGES
• Server sends messages to subscribed clients by sending a
MESSAGE frame
MESSAGE
subscription:0
message-id:007
destination:/queue/a
content-type:text/plain
hello queue a^@
WELL, THAT SEEMS SIMPLE ENOUGH
WALK BEFORE YOU RUN …
• ABL Socket issues
• Read-response procedure
• ABL Issues
• Memory leaks
• Performance issues
SUCCESS !
• All 4GL issues solved
• By better coding 
• Fixed sockets by :enabled
• Fixed memory leaks by better use of events
PLATFORMS
• 4GL Clients
• Win32, webspeed, character
• NOT Appserver
• Linux supported (as tested by Tom Bascom)
• Many other clients
WHAT CAN WE DO WITH THIS ?
• 4GL – 4GL communication
• Internal, local, network, internet
• Node.js  4GL
• Web browsers  4GL
• Rest / curl / php / ruby / js  4GL …
HOW MUCH IS THIS GOING TO COST ?
• Nothing. Nada.
• Server is free (ActiveMQ)
• http://activemq.apache.org/
• 4GL Stomp adapter is free
• https://bitbucket.org/jmls/stomp/overview
• MIT licence. Free to use in commercial products
DEMOS,
QUESTIONS,
DEBATE