How to implement tLoop in Talend? - talend

Question

I'm new to Talend and need an example job to implement tLoop. I want to run a job 10 times if it fails. I've looked at the documents, but I can't seem to figure this out.

Answer 1

This answer has 2 sections
Creating a loop with tJava
Retying a failed connection to a data source 5 times (with adding tJavaFlex)
___________________________________
SECTION 1 : Creating a loop with tJava
-----------------------------------------------------------
I just write a tJava component and then iterate to false.
Like this
Step 1: create a context variable
Step 2: write some java code in tJava (tJava1)
// setting loop flag
context.continueLooping = true;
//log.info("Starting job...");
then connect On Component Ok
Step 3: Create the tLoop
in the loop condition put your context context.continueLooping
which should be true by the first iteration.
then iterate
to the next tJava (tJava2)
if ( ((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) == 1)
{
// code
}
else if(((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) == 2)
{
// code
}
else if (((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) == 3)
{
// code
}
else if (((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) == 4)
{
// code
}
else if (((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) == 5)
{
// code
context.continueLooping = false;
// log.info("DONE");
}
else
{
context.continueLooping = false;
// log.error("out of bounds...");
}
this tJava runs different code for each iteration till it reaches 5
I use this area to count stuff and load value to other contexts and more.
Then it runs the nest part n times till the context value is set to false.
___________________________
SECTION 2 : TO Retry Failed Connections
___________________________
if you need to retry a DB connection.
add a tJavaFlex between tLoop1 and tJava2 like so
and add the following code in the 3 sections
Start:
// start part of your Java code
try{
Main:
// here is the main part of the component,
// a piece of code executed in the row
// loop
if ( ((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) > 1)
{
Thread.sleep(10000);
}
End:
// end of the component, outside/closing the loop
}catch (Exception e) {
if ( ((Integer)globalMap.get("tLoop_1_CURRENT_ITERATION")) > 5)
{
context.continueLooping = false;
}
else
{
System.out.println("Connection failed. Retrying...next");
}
}
and add On Component Ok tJava with the code to stop looping on the success (tJava3)
context.continueLooping = false;