Feature Comparison of Java Job Schedulers
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At Carfey Software, we love our flagship product, Obsidian Scheduler. We believe that Obsidian is the best choice for most scheduling needs. Why? Because Obsidian is carefully designed to meet both simple and complex requirements. We think it stacks up well whether you are struggling with an existing scheduler or investigating if you should once again use one of the de facto scheduler solutions on your new project, or perhaps are just curious about alternatives.
So we decided to compare Obsidian to Quartz, cron4j and Spring. And if the technology you’re considering isn’t listed here, why not use these items as a guide to consider what is important for your upcoming project? For a brief overview, check out our feature comparison.
Real-time Schedule Changes / Real-time Job Configuration
|Yes||No native interactivity||No|
Initially, these may not seem very important, but we’ve all likely dealt with situations where we had to temporarily disable a job or change when it runs due to changes in requirements, unexpected technical problems or simply unanticipated behaviour. Obsidian provides both a UI and a REST API to make these changes and they can be effective at the very next minute. Quartz and cron4j are able to make these changes, but they are done via an API or via configuration, so it’s up to you as the developer to find a way to expose this functionality in real-time.
|Ad-hoc Job Submission||Yes||No||No native interactivity||No|
|Configurable Job Conflicts||Yes||No||No||No|
As you can see, this means supporting something like ad-hoc job submission is also not easily done with these other technologies, when the library even supports it.
When it comes to configurable job conflicts, these too can be configured in real-time. So, if it turns out that two jobs that are executing concurrently are colliding with each other and this is while they are executing in your production environment, you can actually adjust to the circumstance with Obsidian, whereas with other schedulers, you may not have any recourse but shutting down, changing code or configuration, and then starting up again. With Obsidian’s conflict support, you could even choose the conflict configuration as a medium- or long-term solution.
Code- and XML-Free Job Configuration
Obsidian provides you with a rich administration UI exposed via a standard web application. We even support job parameterization that can be validated and enforced via the UI if your job is so designated. Quartz and cron4j are essentially just libraries, so they require code and/or configuration as their means of job configuration.
Since we want to be able to make these types of dynamic changes, Obsidian provides a write access user role which corresponds to scheduler operators who can access the UI and perform the necessary changes. All these changes are audited in Obsidian and these audit logs are searchable from the UI, giving you insight into what changes have been made by your team members.
Job Event Subscription/Notification
Quartz and cron4j can handle event notifications via custom listeners. But again, if you want to send out emails on certain events, you have to write that code. If you want to change who receives which notifications, you either expose the mechanism to make those changes, or push new configuration files or possibly even new code. Obsidian chooses not to use custom listeners since we have provided natively the means to do the things these listeners would be used for. Custom listeners would otherwise be needed to handle something like job chaining, but Obsidian supports that natively, even allowing for configuration of conditional chaining decisions. For all events, items can be subscribed to generally or by specific entity, e.g. subscribe to all job failures or just a specific job’s failures.
|Job Chaining||Yes||Implement yourself using custom listeners||No|
Obsidian goes one step further and even allows you to be subscribe and be notified to a broader set of events. For example, you can be notified when an Obsidian node is shut down, when someone changes a job configuration item, when someone changes a system configuration item, and so on. And all notifications are logged in the system for review.
Monitoring & Management UI
Obsidian’s monitoring and management UI is powerful, yet very easy to use. You can even play around with it at our live, functional and interactive demo site to see for yourself. Or download Obsidian and have a local version running against an in-memory DB and bundled servlet container within minutes. Quartz does have an add-on pay product that provides some UI. But Obsidian’s UI is free to use even if you use Obsidian’s free single-node.
We’ve discussed management already, but monitoring and investigating is another key part of keeping software running smoothly. If a job fails or a job seems to have run with unexpected criteria, having to gain access to log files and then pore over them to try to find the problem is inefficient, unproductive and a frustrating process for support staff and developers alike. Obsidian’s UI can grant read-only access to support and developer staff so they can review the details of job executions (both success and failures). Filtering and custom search criteria can be used to drill down and find the relevant detail all without ever having to share or transfer files around.
Zero Configuration Clustering and Load Sharing
If Obsidian is running, it natively has the ability to be clustered providing you with load sharing, reliability and failover. Every Obsidian Scheduler instance of any type automatically joins the existing pool/cluster or establishes it if it is the first one on the scene. No extra configuration required. No communication between servers necessary. No multicast, no replication of data between servers. This means that you can easily swap out hardware in case of failure or add a new member for load sharing with ease. Of the comparison technologies, only Quartz supports clustering, but it requires special advanced configuration. Also, to change from non-clustered mode to clustered mode would require taking the existing Quartz instance down.
|Job Execution Host Affinity||Yes||No||Not Applicable|
Obsidian in its pooling also supports host specificity so that within a cluster, specific nodes can be designated as the allowable execution nodes for a given job.
Scripting Language Support in Jobs
No Java scheduler can really guarantee with fine precision when a job will fire. Busy hardware could easily lead to pauses or delays in any strategy to fire any activity at an expected time. As such, and due to the performance degradations that would be associated with more aggressive scheduling, we made a decision with Obsidian to support only minute-level precision for job scheduling. If you absolutely require more aggressive and precise scheduling knowing there are no assurances, consider the alternatives above.
Job Scheduling & Management REST API
Obsidian introduced a REST API in version 1.5 to ease integration into other applications and software environments, regardless of the technology used. A complete range of job, scheduling and host management features are exposed via the API. This allows you to integrate Obsidian into external monitoring systems or perhaps even writing Obsidian jobs to react to specific situations. For example, if a job that runs hourly has been failing continually over a period of many hours, perhaps you would want automatically disable it. The API can also be used to retrieve the available execution and logging data in Obsidian and could be used for generating reports or informing interested parties of pertinent activity.
Custom Calendar Support
Quartz does have a feature to support custom calendars. This allows you to reference custom scheduling options in your job’s configured schedule. For example, perhaps you would want to run a job on every weekday, skipping certain business holidays. You can do so with Quartz, but not so with any of these other schedulers unless you were to put custom code in the job itself.
Obsidian has many additional features that haven’t been detailed here, such as configurable recovery options, resubmission of failed jobs, parameterized job support, job configuration validation, job results storage/retrieval and so on. In practice, many developers and even project managers gravitate toward these de facto solutions, but for too long we in the developer community been fighting with these scheduling technologies and contending with the inferior results. Try our live, functional and interactive demo site to see for yourself. If you like what you see, download Obsidian and be refreshed with this easy-to-use and feature-rich scheduler.
Published at DZone with permission of Craig Flichel, DZone MVB. See the original article here.
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