Difference between revisions of "Building Data Agents Using the Messaging Functions"
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endif | endif | ||
| − | + | sendmail(email.from, email.to,email.cc, email.subject, email.message) | |
mailclose() | mailclose() | ||
return | return | ||
</code> | </code> | ||
| − | But first, messages will need to added to the queue before the Data Agent can process them. The following example will add a XML encode email message to the queue. | + | But first, messages will need to be added to the queue before the Data Agent can process them. The following example will add a XML encode email message to the queue. |
<code lang="recital"> | <code lang="recital"> | ||
mqdes=mqopen("/recital_mail") | mqdes=mqopen("/recital_mail") | ||
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===Running the Simple Data Agent=== | ===Running the Simple Data Agent=== | ||
| − | + | Once you have built your Data Agent it can be easily run from the operating system in the background. The following example will run a Data Agent called mydataagent on Linux | |
| + | |||
| + | recital mydataagent & | ||
| + | |||
| + | This process can be setup to start automatically when the system is started by to the process control initialization. For more information on this issues a "man init" | ||
Latest revision as of 07:06, 26 October 2009
Contents
Building Data Agents Using the Messaging Functions
What Is Message Queuing
Message queuing is a communication tool that allows applications to reliably interconnect. The queue acts as a holding container for messages as they are sent between applications. The applications send messages to and read messages from queues to communicate back and forth. An application writes a message to a queue, which will then be received and processed by another application at some point determined by the receiving application. This type of communication is designed for asynchronous use where the applications involved are not waiting for an immediate response from the other end.
What are Data Agents
Data agents are applications written in the Recital scripting language that use the message queue functions to manage the transmitted data. Typically a data agent runs in the background reading data from the message queue and processing it. Any Recital application can open a message queue and transmit data to the Data Agent.
Building a Simple Data Agent
In this simple Data Agent example we will open a queue called recital_email which sends XML encoded email messages.
First we need to open a the queue
mqdes=mqopen("/recital_mail") // Check for error if (mqdes < 0) debug(strerror(error())) return endif
Then we need to wait in a loop processing incoming data.
do while .t. // Read each message do while (mqcurmsgs(mqdes) > 0) // Read the next message mstr=mqreceive(mqdes) // Decode the xml message email = xml_decode(mstr) // process the message process_email(email) enddo // wait 1 second before retrying sleep 1 enddo
When we have finished we can close the queue
mqclose(mqdes)
The following code is for the process_email() function
function process_email(email) // Open SMTP for sending m_open = mailopen("mailserver.company.com","username","password","SMTP") if not m_open debug(mailerror()) return endif sendmail(email.from, email.to,email.cc, email.subject, email.message) mailclose() return
But first, messages will need to be added to the queue before the Data Agent can process them. The following example will add a XML encode email message to the queue.
mqdes=mqopen("/recital_mail") // Check for error if (mqdes < 0) debug(strerror(error())) return endif declare email[] email.from = "info@recital.com" email.to = "fred@recital.com;sue@recital.com" email.cc = "bert@recital.co.uk;linda@recital.co.uk" email.subject = "Update alert" email.message = "Dear All" + chr(10) + "This is an alert message"; + chr(10) + "Best regards" + chr(10) + "Recital" mqsend(mqdes, xml_encode(email)) mqclose(mqdes)
Running the Simple Data Agent
Once you have built your Data Agent it can be easily run from the operating system in the background. The following example will run a Data Agent called mydataagent on Linux
recital mydataagent &
This process can be setup to start automatically when the system is started by to the process control initialization. For more information on this issues a "man init"
