Hi I would like to know how many of you have used Workflow in your production environment and Was it good idea? I mean we can create the same thing using DB and scheduler service
We use WF in our production enviorments. We have 6 different workflows that can be run. These split into 3 statemachine and 3 sequences. I would use it again in some circumstances, but I would not in others. I would claim that the statemachine part of the workflow was tacked on the end quickly, I'm not sure it a core part of the workflow all the way through design.
I would use workflow again for short running processes like quotes or transforming things before sending them to supliers that kind of thing.
I would not want to do it again for a long running statemachine - mainly because there is not a built in WF upgrade process so we ended up writing our own. There are also a lot of concepts to get your head around (affectionalty known as gypsy curses with in our development team).
I would also be slightly concerned about performance: our App server is currently running flat out (ok I am restarting 8000 workflows at the moment). This is especially a problem if you integrate it directly into WCF using the (.NET 3.5) send and recieve activities - there are some properly crazy config settings you have to set to allow it run multiple workflows at once.
Anyway, as I said: it is useful, I would use it again, but not for another statemachine.
Also see Please confirm: Is Windows Workflow Foundation a good horse to be backing right now?
We use Sharepoint, which uses WF for its workflows. It works pretty well and is fairly easy to customize. If you need an advanced workflow, WF can support it but it will take some training to learn the ins and outs.
You could roll your own workflow, but why reinvent the wheel? WF is built into the .NET 3.0+ framework and is pretty robust, so you might as well take advantage of it.
Most people say all the good things about Workflows but I have observed that they introduce unnecessary code complexity and maintenance problems. They are suitable for a particular class of problems. other then that they need a lot of code plumbing and maintenance nightmares.
Related
I am looking into developing a commercial application using PHP. Since I have experience in CodeIgniter and it has been working well for me, I decided to use it. Now, if ever my application comes to a point that it needs to grow and have to have custom modifications in the platform, is it possible to modify the CodeIgniter source code to the point that it's far from the original?
I'd strongly recommend not modifying the source code as this is the back bone of the application will make updating to futures releases of codeigniter impossible.
Instead you should be creating your own classes/libraries that extend the core bases. This is best practice.
The codeigniter users guide has some fantastic information regarding this, http://codeigniter.com/user_guide/general/creating_libraries.html
Good luck.
Don't modify it, extend it. Ellislab is good about releasing bug fixes and patches, and the last thing you want is to have to re-engineer all the updates into your new hybrid everytime they release updated source code. Plus, different features and bug fixes are released at different paces for the core and reactor, so unless you plan to lock your framework in at the current version, extending is the way to go.
The good news is CI is built for and encourages extensions of the source. The system folder and the application folder separation are a clear indication of how you should segregate your enhancements from the base libraries.
CodeIgniter is written in PHP. You can completely rewrite the framework anyway you like. So the answer is "yes".
There are many big websites that were written in a different language or build on a framework when they started and have been rewritten many times since. I think a lot of developers (mostly freelancers) are over-thinking when starting out. When I start a project, then I try to get it done and get it out in the web asap. If a website starts taking of - and most of the times start making you money - then you can always take the time to rewrite it.
I think it is a lot more important to spend time when you plan and design your database and tables. I think it is a lot harder to redo parts of your database later on then it is to rewrite the code that uses the data.
Just my 2 cents.
If you have used CI, then you should know that being a PHP framework that all of the source-code is there in the download, furthermore opening the system and application folders and looking through there will tell you a lot. Yes all of the source is there in plain English (plain programming English) and not only is it in plain English but has been extensively documented inside and out (literally that is in the source and in the user-guide). CI gained initial fame from that simple fact, that all code is extensively and meticulously documented.
Beyond all that, the question itself raises concerns that maybe you should study CI a bit further before writing commercial applications using it. Ci is a powerful and very easy to use PHP framework, but it is not a WYSIWYG. In my opinion, a coder should know his tools inside and out in order to be able to create a solid secure and trusted application. The first measure of which is to read the user manual, you should know at the very least everything in it, and since there are 12 sections in it that cover everything from extending CI libraries to creating your own libraries, and everything in between I would say you need to spend a little more time with it.
I want to say though, I am not being rude or trying to shame you in any way I am simply saying that you should learn the framework a bit more before venturing into a commercial application using it.
In the early days of PHP people realized how amazingly easy it was to use and how fast you could write an application with it. At the time the major options where very difficult for new and hobby programmers to use or involved expensive software to run, PHP was free, easy to learn and most of all ran on a free OS. It also took hardly any setup to get going, you could download PHP and essentially be programming in minutes. All of these factors lead to the almost destruction of the language.
Entry level programmers were destroying it with bits of code taken from other applications, never knowing (or caring) what the code actually did beyond the simple fact that it did what they wanted at the time, never considering or even investigating if the code might be harmful. Because of this practice PHP applications that had grown to Goliath sized websites, taking thousands of hits an hour were:
beginning to crash
being hacked to reveal sensitive customer/client data
generally crumbling all around the web
All because since the language was so easy to use that people had taken advantage of it and failed to take time to learn it. PHP was becoming a joke to other professional programmers and wasn't even thought of as a viable application language by many who had dubbed it "the copy and paste" language.
So my advice to you, please take the time to know your tools inside and out, what makes them tick, if they have any gotchas and where they are vulnerable. I understand that in order to learn a language to a professional level you have to build with it so I suggest that you take it slow with CI stick to the core for now. Trust me when I say that even in its purest form CI is an amazing and powerful tool that in the right hands can create awesome powerful web application, but in the uneducated/inexperienced hands it can create havoc and destruction.
So (stepping off of the soap box) I simply ask that if you are serious about creating commercial applications period that you take your time and learn your tools/language become as close to an expert on them as possible. I gurentee that if you do that you will always have work when you need it and you will spend less hours beating your head against the table or worse explaining to a client why their site is down.
I truly wish you good luck, just slow down and learn your trade and you will do just fine.
Yes, Codeigniter is an open source framework. However, I would advise against modifying the core of Codeigniter, as most files can be extended and rewritten safely without modifying the core files which will cause you headaches if you ever decide to update.
To extend a core class by default you would do this in Codeigniter. We'll extended the parser class for this example, but this applies to all classes pretty much. This link in the comprehensive user guide will give you all the information you need to extended and overload methods inside of a Codeigniter core class: http://codeigniter.com/user_guide/general/core_classes.html
I'm looking for some comparison between Quartz.NET and Windows Scheduled Tasks?
How different are they? What are the pros and cons of each one? How do I choose which one to use?
TIA,
With Quartz.NET I could contrast some of the earlier points:
Code to write - You can express your intent in .NET language, write unit tests and debug the logic
Integration with event log, you have Common.Logging that allows to write even to db..
Robust and reliable too
Even richer API
It's mostly a question about what you need. Windows Scheduled tasks might give you all you need. But if you need clustering (distributed workers), fine-grained control over triggering or misfire handling rules, you might like to check what Quartz.NET has to offer on these areas.
Take the simplest that fills your requirements, but abstract enough to allow change.
My gut reaction would be to try and get the integral WinScheduler to work with your needs first before installing yet another scheduler - reasoning:
no installation required - installed and enabled by default
no code to write - jobs expressed as metadata
integration with event log etc.
robust and reliable - good enough for MSFT, Google etc.
reasonably rich API - create jobs, check status etc.
integrated with remote management tools
security integration - run jobs in different credentials
monitoring tooling
Then reach for Quartz if it doesn't meet your needs. Quartz certainly has many of these features too, but resist adding yet another service to own and manage if you can.
One important distinction, for me, that is not included in the other answers is what gets executed by the scheduler.
Windows Task Scheduler can only run executable programs and scripts. The code written for use within Quartz can directly interact with your project's .NET components.
With Task Scheduler, you'll have to write a shell executable or script. Inside of that shell, you can interact with your project's components. While writing this shell code is not a difficult process, you do have to consider deploying the extra files.
If you anticipate adding more scheduled tasks over the lifetime of the project, you may end up needing to create additional executable shells or script files, which requires updates to the deployment process. With Quartz, you don't need these files, which reduces the total effort needed to create and deploy additional tasks.
Unfortunately, Quartz.NET job assemblies can't be updated without restarting the process/host/service. That's a pretty big one for some folks (including myself).
It's entirely possible to build a framework for jobs running under Task Scheduler. MEF-based assemblies can be called by a single console app, with everything managed via a configuration UI. Here's a popular managed wrapper:
https://github.com/dahall/taskscheduler
https://www.nuget.org/packages/TaskScheduler
I did enjoy my brief time of working with Quart.NET, but the restart requirement was too big a problem to overcome. Marko has done a great job with it over the years, and he's always been helpful and responsive. Perhaps someday the project will get multiple AppDomain support, which would address this. (That said, it promises to be a lot of work. Kudos to he and his contributors if they decide to take it on.)
To paraphrase Marko, if you need:
Clustering (distributed workers)
Fine-grained control over triggering or misfire handling rules
...then Quartz.NET will be your requirement.
It takes at least 7 assemblies and restricting my AddIn's data model to data types that remoting can deal with before the appdomain isolation features begin to work. It is so complex! The System.AddIn teams blog implies to me they were trying to re-create a mental model of COM, a model I never understood very well in the first place and am not sold on the benefits. (If COM is so good why's it dead?-rhetorical question.) If I don't need to mirror or interop with legacy COM (like VSTO does using System.AddIn), is it possible to just create some classes that load load in a new AppDomain?
I can write the discovery code my self, I've done it before and a naive implementation is pretty fast because I'm not like iterating over the assemblies in the GAC!
So my specific question is, can I get the AppDomain isolation that AddIns provide with a few code Remoting snippets, and what would those be?
I'm not entirely sure that that any answer to your question meets the terms of the site - there is no solution.
Yes, remoting is easier as it is done for you. However, it is highly controlled and as you identified, requires a little work to plumb it all together. The cache file spewed out by the discovery process is hardly welcome either.
System.AddIn excels at isolation, which is actually a bit of an arse to put together from scratch in a robust, flexible way. It supports cross process hosting and fairly simple passage of user WPF elements from one domain to another.
One thing to remember however is that MAF's target audience is not those who are trying to connect two applications together. It is targeting developers wanting pluggable yet secure systems (cross process hosting protects the root application from unhandled exceptions, appdomains allow for executing potentially foreign code with defined security). From most communication, direct yourself straight towards System.Runtime.Remoting or WCF.
If you want to continue with System.AddIn, consider the pipeline builder plugin for visual studio!
In conclusion - you can get System.AddIn isolation using Remoting but to get a decent system you will require more than a few snippets. I am trying to replicate it myself and am tripping up all over remote interface component - something System.AddIn does without a hitch.
After messing around with System.Add for quite a while, I'm convinced that it was added as a one-off special purpose solution for Microsoft use. I'm surprised it got elevated to a core part of the .NET framework. It doesn't seem to have the refinement and polish needed for a general .NET framework component.
I'd like to find an alternative way to create .NET managed add-ins that doesn't require so much effort.
Is WF used at user interface or business layer? If at UI layer, then does someone coding in business layer even need to use or learn it?
Chris offered a great answer, so I'll take a different tack. Workflow is really not the same as logic. Workflows are generally compositions of logic, which makes them a complimentary contributor to the whole. Where a business component nicely encapsulates a single piece of business rules or behavior, a workflow composes multiple business components, rules, and behavior to meet the needs of larger, longer-running business processes.
Workflows can fit anywhere, filling process needs for UI, business, and even data layers. If you do end up using WF, I highly recommend that you train your general development staff, so that there is broad knowledge and understanding. Despite having a visual aspect to it, WF still requires some low-level coding to build up a library of activities and such that workflow creators and maintainers will use.
EDIT:
Its up to you whether to use it or not. Generally, WF is used by larger projects, because WF offers a valuable return on investment. WF is harder to use than simply writing code. There is a fairly steep learning curve, requires a different way of approaching business problems, and requires special skill sets. Providing code to WF adds overhead, as you have to write activities that may be used in workflows, as well as build the workflows themselves.
If you think that using WF for your small project will provide a valuable return on investment, then go for it. You will need to both recoup the initial costs of training, infrastructural implementation, and deployment, as well as providing long-term, tangible cost savings over simply writing code to solve the problems at hand. I would be doubtful that WF will offer a small project such ROI. For larger projects, or multiple integrated projects for a single large company, it is much easier to realize that ROI than it is with smaller projects, which is why workflow platforms like WF are usually only used on that scale.
WF is the interface to the buisness layer.
Workflows are a declarative way of writing programs by linking together pre-defined activities rather than an imperative programming model of writing lines of code. IN addition, you have many graphical tool that allow you to wrtie workflows. shuch as black pearl, K2 and sharepoint designer.
They are very much used and are well worth learning. I started using then in sharepoint and ms crm. I now always look to workflows to solve my common problems.
here are a few links:
mirosoft msdn.microsoft.com/en-us/netframework/default.aspx
Wkik: http://en.wikipedia.org/wiki/Windows_Workflow_Foundation
WF is mostly understood quite imperatively - a sequence of chronological events.
However, if you delve deeper you can combine activities in different ways. A good example are the state-based workflows that are usually also shown when presenting WF. WF allows you to put the Workflow into an idle mode: It's current state is persisted and reloaded once e.g. an external event takes place. As such, workflows can be useful in tracking long-running interactions where the system has to wait e.g. for some external process to end or some user to interact with the system.
I'd say that WF wouldn't be terribly useful in the UI context. They are better suited as a backend module to express processes integrating several services that have a tendency towards changing in time.
From my point of view, though, it is noticable that WF is a version 1 product: There are a number of awkward things that may guide you into code that is hard to maintain, parts of the infrastructure are quite complex to be used, you may find some API inconsistencies here & there.
There is also a guideline out there what you shouldn't do if you ever want to port your workflows to the next generation of WF.
I work in a very small shop (2 people), and since I started a few months back we have been relying on Windows Scheduled tasks. Finally, I've decided I've had enough grief with some of its inabilities such as
No logs that I can find except on a domain level (inaccessible to machine admins who aren't domain admins)
No alerting mechanism (e-mail, for one) when the job fails.
Once again, we are a small shop. I'm looking to do the analogous scheduling system upgrade than I'm doing with source control (VSS --> Subversion). I'm looking for suggestions of systems that
Are able to do the two things outlined above
Have been community-tested. I'd love to be a guinae pig for exciting software, but job scheduling is not my day job.
Ability to remotely manage jobs a plus
Free a plus. Cheap is okay, but I have very little interest in going through a full blown sales pitch with 7 power point presentations.
Built-in ability to run common tasks besides .EXE's a (minor) plus (run an assembly by name, run an Excel macro by name a plus, run a database stored procedure, etc.).
I think you can look at :
http://www.visualcron.com/
Consider Cygwin and its version of "cron". It meets requirements #1 thru 4 (though without a nice UI for #3.)
Apologize for kicking up the dust here on a very old thread. But I couldn't disagree more with what's been presented here.
Scheduled tasks in Windows are AWESOME (a %^#% load better than writing services I might add). Yes, not without limitations. But still extremely powerful. I rely on them in earnest for a variety of different things.
If you even have a slight grasp on c# you can write as custom "task" (essentially a console application) to do, well, virtually anything. If persistent/accessible logging is what you're after, why not something like Serilog or NLog? Even at the time of writing, it had a very robust feature set. This tool in and of itself, in conjunction with some c#, could've solved both your problems very easily.
Perhaps I'm missing the point, but it seems to me that this isn't really a problem. At least not anymore...
If you're looking for a free tool there is plenty of implementations for the popular Cron tool for Windows, for example CRONw. It's pretty easy to configure and maintain. You could easily write add custom WSH scripts to send your emails and add log entries.
If you're going commercial way BMC Control-M is arguably one of the best but I don't believe that it is particularly cheap.
You may also consider some upcoming packages like JobScheduler
Pretty old question, but we use Jenkins. Yes its main purpose is for CI\CD, but its also a really nice UI for CRON with a ton of plugins and integrations.