Difference between revisions of "Building Data Agents Using the Messaging Functions"
Peterkelly (Talk | contribs) (→Building a Simple Data Agent) |
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===Building a Simple Data Agent=== | ===Building a Simple Data Agent=== | ||
| − | In this simple Data Agent example we will open a queue called | + | 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 | + | First we need to open a the queue |
| − | mqdes=mqopen("/ | + | <code lang="recital"> |
| + | mqdes=mqopen("/recital_mail") | ||
// Check for error | // Check for error | ||
if (mqdes < 0) | if (mqdes < 0) | ||
| Line 17: | Line 18: | ||
return | return | ||
endif | endif | ||
| − | + | </code> | |
Then we need to wait in a loop processing incoming data. | Then we need to wait in a loop processing incoming data. | ||
| + | <code lang="recital"> | ||
do while .t. | do while .t. | ||
// Read each message | // Read each message | ||
| Line 25: | Line 27: | ||
mstr=mqreceive(mqdes) | mstr=mqreceive(mqdes) | ||
// Decode the xml message | // Decode the xml message | ||
| − | + | email = xml_decode(mstr) | |
| − | // | + | // process the message |
| + | process_email(email) | ||
enddo | enddo | ||
// wait 1 second before retrying | // wait 1 second before retrying | ||
sleep 1 | sleep 1 | ||
enddo | enddo | ||
| − | + | </code> | |
When we have finished we can close the queue | When we have finished we can close the queue | ||
| + | <code lang="recital"> | ||
mqclose(mqdes) | mqclose(mqdes) | ||
| + | </code> | ||
| + | |||
| + | The following code is for the process_email() function | ||
| + | <code lang="recital"> | ||
| + | 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 | ||
| + | |||
| + | mailsend(email.from, email.to,email.cc, email.sub, email.message, email.attachments) | ||
| + | mailclose() | ||
| + | return | ||
| + | </code> | ||
===Running the Simple Data Agent=== | ===Running the Simple Data Agent=== | ||
===Summary=== | ===Summary=== | ||
Revision as of 02:21, 23 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 mailsend(email.from, email.to,email.cc, email.sub, email.message, email.attachments) mailclose() return
