Scheduled Tasks with Quartz - JDBC - java

I'm trying to make a mini web application for reminders, I deploy Quartz Scheduler to handle the issue of launch events reminder, I have understood the tasks (Jobs) and programmers (Schedulers) can be configured from a Database with JDBC, I have searched and can not find an example where I show what information should I put on the tables and I run java code to start operating scheduled tasks. If someone can have an example or something that I can serve this purpose, they are grateful.

You have understood wrong. You can use any JobStore (including the JdbcJobStore to store your jobs/triggers/etc. but creating them manually in the database is a bad idea™.
Depending on how you are using Quartz you can set it up, either using SPRING or using the Fluent syntax (which I believe is the preferred method these days).
Further reading: http://quartz-scheduler.org/documentation/quartz-2.1.x/tutorials/tutorial-lesson-09

Related

Streaming data to SQL database every 10 minutes with Springboot

Currently I am trying to improve my skills with Springboot applications and I wanted to know if it is possible for a Springboot application to insert into a MySQL database every 10 minutes (or some quantum of time) while the application is deployed on a server (I am using Elastic Beanstalk), and if so how would I be able to do this and if I would need additional tools to accomplish this.
You can use the #Scheduled annotation.
Here is a pretty nice example using cron, fixedRate, and fixedDelay.
Just be mindful that if you are using dynamic schedules (as shown below)
#Scheduled("${my.dynamic.schedule}")
public myScheduledMethod() {
//do some tasks here
}
that you may also introduce logic to ensure all instances are not running at the same time, performing the same task, to avoid redundant behavior.

Notify Java application of changes in Apache Derby database

I have a Java application that can save and retrieve data from an Apache Derby database using JDBC. I would like to update the view of every user when changes are made in the database.
I tried using a for-loop that polls the database every few seconds, but that uses loads of processor time as expected. I've also heard about TimeTask and ScheduledExecutorService. I'm not sure how they work but i imagine they are a better alternative to the for-loop. However they would also have to check the database, which i find less ideal than having the database notify of changes.
I've read about database Triggers, which i think might be the best solution? However, all the examples i find for apache derby only seem to trigger other changes in the database and not the Java application.
Is it possible to use a trigger to execute a method in the Java application? If so, how? or perhaps there is another approach to solving the problem that I don't know of?

How to monitor Executors or other Task Executing Threads in Spring MVC

I am creating a web application and in this I will be creating many services and executors to do some tasks.I have extended dispacter servlet and started executors or other threads in init method.Is this the right approach?
Now Suppose if any request comes and that executor or similar task executing thread dies after throwing Exception.
1.I suppose that it will affect other requests also.So what shall I do in such cases?
2.How can I create a monitor thread which will check if all critial tasks executing thread and executors are properly running?
3.Should I keep another backup executor prepared and deferred to takeover the failed executor in such situations?If so then how?
It is an old one, but maybe it would help someone :)
For ExecutorService there is a nice example on how to approach the problem in Codahale Metrics: https://github.com/dropwizard/metrics/blob/master/metrics-core/src/main/java/com/codahale/metrics/InstrumentedExecutorService.java
I did not find anything as good for the Spring AsyncTaskExecutors :/
Its been a while since I have used an Executor, are you using one of the built-in executors from Java, Spring, or are you rolling your own? Spring has a bunch, and I think Java gives you two or three concrete implementations.
Anyhow, I think the answer would be to roll some sort of monitoring service, like maybe something using JMX if you have that available. If you wanted to wire your Executors auto-magically you could use the ApplicationContextAware interface to get a reference to the ApplicationContext, which has a method called getBeansOfType(). If you want to take the more straight-forward approach, then you can simply write your monitoring service to inject the executors in there directly.
Another option would be to get an external monitoring framework/app. Something like Dynatrace, which attaches to the JVM process and monitors things or, if you don't mind switching app servers, SpringSource's tcServer, which has optional instrumented Spring JARs and provides a ton of out-of-the-box monitoring.

Java scheduling Vs SQL scheduling

Here is my requirement:
a date is inserted in to a db table with each record. Two weeks
before that particulate date, a separate record should be entered to a
different table.
My initial solution was to put up a SQL schedule job, but my client insisted on it being handled through java.
What is the best approach for this?
What are the pros and cons of using SQL schedule job and Java scheduling for this task?
Ask yourself the question: to what domain does this piece of work belong? If it's required for data integrity, then it's obviously the DBMS' problem and would probably best be handled there. If it's part of the business domain rather than the data, or might require information or processing that's not available or natural to the DBMS, it's probably best made external.
I'd say, use the best tool for the job. Having stuff handled by the database using whatever features it offers is often nice. For example, a log table that keeps "snapshots" of status updates of records in another table is something I typically like to have a trigger for, taking that responsibility out of my app's hands.
But that's something that's available in practically any DBMS. There's the possibility that other databases won't offer the job scheduling capacities you require. If it's conceivable that some day you'll be switching to a different DBMS, you'll then be forced to do it in Java anyway. That's the advantage of the Java approach: you've got the functionality independently of the database. If you're using pure JDBC with standard SQL queries, you've got a fully portable solution.
Both approaches seem valid. Consider what induces the least work and worries. If it's done in Java you'll need to make sure that process is running or scheduled. That's some external dependency. If it's in the database, you'll be sure the job is done as long as the DB is up.
Well, first off, if you want to do it in Java, you can use the Timer for a simple basic repetitive job, or Quartz for more advanced stuff.
Personally I also think that it would be better to have the same entity (application) deal with all related database actions. In other words, if your Java app is reading/writing to/from the db, it should be consistent and also deal with scheduled reading/writings. And as a plus, this way you can synchronize your actions easier, like, if you want to make sure that a scheduled job is running, has started, has finished, you can do that a lot easier if all is done in Java as compared with having a different process (like the SQL Scheduler) doing it.

how to create spring quartz like application?

Hi i want to create an application that works like spring quartz i can use the spring quartz to do the same my native goal is to create job which may have more then one steps to be executed (trigerred) after that there may be depended jobs also and we shold give the functionality to skip the next execution of particular job.
can any one provide the guidance how the spring quartz actually works?
how to create such application in java using spring ?
thanx in advance.
Thank you everybody for spending your valuable time to reply me I got it work and i found following links very useful.
http://www.mkyong.com/spring/spring-quartz-scheduler-example/
http://static.springsource.org/spring/docs/2.5.x/reference/scheduling.html
That all sounds like stuff you can do with spring/quartz and a queue to queue up your "steps" in.

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