We are developing the project by using spring batch partition.Our requirement is we will upload the file and validate the each record from file ,if all the records perfect then only will store in database.for that
We used Spring batch partitioning 1. ItemReader,CustomItemProcessor and CustomWriter.In ItemReader will read the data and CustomItemProcessor will validate the data finally CustomItemWriter will persist all the data in preparedStatement.Once all the process done finally will commit the data,how to do in one connection with more than one thread
You should be reading the csv file! You can probably do it in two ways:
Using parallel streams: Map each record into a object and with the Java8 parallel stream API you can achieve this
NIO: Using Non blocking IO you can achieve this a way faster.
This post might be helpful : How to read all lines of a file in parallel in Java 8
Related
I need to read from a DB and based on that result I need to fetch data from another DB which is on another server and after need to write it in file. Now solution that came in mind to use Spring Batch reader for reading from first DB and using we can read from 2nd DB in process.
But in this process what I feel that in process reading is not good idea because it processes single data in one time. (Please correct me if I am wrong)
Is there any other way to do this so that we can perform this task in efficient way.
Thanks in advance
Please Suggest me what could be the options
i want to read multiple xml files in spring batch , and before reading i should validate the name of each file and put it in the context , how can i process ?
is it possible to have this senario using tasklet and reader writer processor ?? :
folder : file1.xml file2.xml file3.xml
validate filename (file1.xml) -- read file1 -- process -- write
then
validate filename (file2.xml) -- read file2 -- write
validate filename (file3.xml) -- read file3 -- write
......
or any other way ??????
There are three approaches you can take with this. Each has it's benefits and weaknesses.
Use a step to validate
You can set your job up with a validateFileName step that preceedes the step that processes the files (say processFiles). The validateFileName step would do any validations on the file name needed then provide the files to process to the next step. How it communicates this could be a simple as moving the valid files to a new directory or as complex as using the job's ExecutionContext to store the names of the files to process.
The advantage of this is that it decouples validation from processing. The disadvantage is that it makes the job slightly more complex given that you'd have an extra step.
Use a StepExecutionListener to do the validation
You could use a StepExecutionListener#beforeStep() call to do the validation. Same concepts apply as before with regards to how to communicate what validates and what doesn't.
This may be a less complex option, but it more tightly couples (albeit marginally) the processing and validation.
Use an ItemReader that validates before it reads
This last option is to write an ItemReader implementation that is similar to the MultiResourceItemReader but provides a hook into validating the file before reading it. If the file doesn't validate, you would skip it.
This option again couples validation with the processing, but may provide a nice reusable abstraction for this particular use case.
I hope this helps!
I have Batch Processing project, wanted to cluster on 5 machines.
Suppose I have input source is database having 1000 records.
I want to split these records equally i.e. 200 records/instance of batch job.
How could we distribute the work load ?
Given below, is the workflow that you may want to follow.
Assumptions:
You have the necessary Domain Objects respective to the DB table.
You have a batch flow configured wherein, there is a
reader/writer/tasklet mechanism.
You have a Messaging System (Messaging Queues are a great way to
make distributed applications talk to each other)
Input object is an object to the queue that contains the set of
input records split as per the required size.
Result object is an object to the queue that contains the processed
records or result value(if scalar)
The chunkSize is configured in a property file. Here 200
Design:
In the application,
Configure a queueReader to read from a queue
Configure a queueWriter to write to a queue
If using the task/tasklet mechanism, configure different queues to carry the input/result objects.
Configure a DB reader which reads from a DB
Logic in the DBReader
Read records from DB one by one and count of records maintained. if
(count%chunkSize==0) then write all the records to the inputMessage
object and write the object to the queue.
Logic in queueReader
Read the messages one by one
For each present message do the necessary processing.
Create a resultObject
Logic in the queueWriter
Read the resultObject (usually batch frameworks provide a way to
ensure that writers are able to read the output from readers)
If any applicable processing or downstream interaction is needed,
add it here.
Write the result object to the outputQueue.
Deployment
Package once, deploy multiple instances. For better performance, ensure that the chunkSize is small to enable fast processing. The queues are managed by the messaging system (The available systems in the market provide ways to monitor the queues) where you will be able to see the message flow.
I am a newbie at Spring Batch and have recently started using it.
I have a requirement where I need to post/write the messages read from each DB record on different queues using single Job. As I have to use reader to read the messages from DB and use processor to decide on which queue I have to post it.
So my question is Can I use single JMSwriter to post the messages on different queues as I have to use single Job and DB Reader.
Thanks in Advance
As I know JMSwriter not supports it (it writes to default destination of jmsTemplate).
But you may just implement your own ItemWriter, inject all jmsTemplates in it and write custom decistion logic to select appropriate destionation and write to it.
Another way - use ClassifierCompositeItemWriter , put a set of JmsWriters to it and select one by your classifier
I am writing a Spring Batch application to do the following: There is an input table (PostgreSQL DB) to which someone continually adds rows - that is basically work items being added. For each of these rows, I need to fetch more data from another DB, do some processing, and then do an output transaction which can be multiple SQL queries touching multiple tables (this needs to be one transaction for consistency reasons).
Now, the part between the input and output should be a modular - it already has 3-4 logically separated things, and in future there would be more. This flow need not be linear - what processing is done next can be dependent on the result of previous. In short, this is basically like the flow you can setup using steps inside a job.
My main problem is this: Normally a single chunk processing step has both ItemReader and ItemWriter, i.e., input to output in a single step. So, should I include all the processing steps as part of a single ItemProcessor? How would I make a single ItemProcessor a stateful workflow in itself?
The other option is to make each step a Tasklet implementation, and write two tasklets myself to behave as ItemReader and ItemWriter.
Any suggestions?
Found an answer - yes you are effectively limited to a single step. But:
1) For linear workflows, you can "chain" itemprocessors - that is create a composite itemprocessor to which you can provide all the itemprocessors which do actual work through applicationContext.xml. Composite itemprocessor just runs them one by one. This is what I'm doing right now.
2) You can always create the internal subflow as a seperate spring batch workflow and call it through code in an itemprocessor similar to composite itemprocessor above. I might move to this in the future.