I have a data loading application that has to be executed multiple times per day at irregular intervals. I am planning to write a service to kick off the downloads and import the data to a database server. Are there advantages to using a standard service over a webservice or vice versa?
I think you're missing the point here.
Web Services typically are used for a form of communication or remote execution. You call a remote function on a web-service to either adjust the behavior of the machine it's running on or to retrieve data from it.
Windows Services are background processes that run on a machine without any "logged on user" being required. They can perform tasks and do things while the user is at the login screen, or do elevated operations. You can talk to services to adjust their behavior or retrieve information, but it's general purpose is different than a webservice.
The biggest notable difference here is that web-services must be called, they don't run on their own.
For your application I would suggest using a Windows (Standard) Service, as you can have it execute code once per day. I would only use a web-service if you've got something else to automate the calls to the web-service and you require a response from the server detailing it's execution result (success/fail/warning/etc...)
You could also consider writing a normal (windows or console) application that is triggered by a Windows Scheduled Task. What you've described doesn't necessarily sound like something that would require a service.
Sounds like a good use of a windows service to me. Off the top of my head, I'd use a windows service if:
1. Work is performed on a scheduled basis (regular or irregular intervals) in the background;
2. No interaction is needed - work is just done in the background and kicks off based on polling or some other type of trigger (message dropped in queue, database value trigger, scheduled timespan, etc.);
3. Needs to be monitored (either starts/stops along with logging) and you can take advantage of WMI, perfmon and event log with little effort.
A web service is better for tasks that are interactive (like if you wanted to initiate the download based upon a request received).
Sounds like a windows service is the approach you should take.
Hope this helps. Good luck!
If "irregular interval" does mean, the application is invoked by another application, I would use a web service.
If the action is scheduled, I would use a windows service.
If you are working with SQL Server (scheduled or not), I would also consider SQL Server Integration Services.
Related
I want to Scheduling in Asp.net
I have following options to implement this
To write SQLServer JOB(I dont want to do this.Dont want to go outside of .Net environment)
Second option is I will write windows service and this window service will call asp.net
webservice then this webservice calls asp.net method
(I also dont need to do this because my hosting provider might not be allow me to install
window service)
Third option is I call my scheduling method in Application_Start event in global class
(Drawback is, webserver will kill thread any time )
To call Scheduling Code in Page_Load event of Home Page(Might be nobody visits my website for hours
,Also page execution might be slow due to scheduling code)
I also found some online services that calls your page at given interval,some are given below
http://www.cronservice.co.uk/new/
http://scheduler.codeeffects.com
Anybody give me bettor solution of this and also explain why it is bettor?
Thanks in Advance
The ASP.NET application isn't the right place to implement scheduling. I would suggest creating a service or a scheduled task that runs in short intervals.
You don't have many options in a shared hosting environment. My host (WinHost) allows remote access to their database, so I was able to create an executable that ran on a local server with Task Scheduler.
The performance isn't great since the database is accessed over the internet, but it's still better than attempting to run pseudo scheduled tasks with ASP.NET.
Some hosts also offer a service that will request a url within your site on a scheduled basis. However, this didn't work for me because the task I had to run took longer than the request timeout.
There is no one solution that fits all. SQL jobs and windows jobs (scheduled thru windows task scheduler) are very widely used. In one of my previous work places they had jobs that ran on multiple platforms (mainframe,windows,sql server). Failure in some of these jobs, would cost in thousands by the day. So they employed something called ESP. This software monitored jobs on all platforms and sent a message to the control room in case of a failure.
If you throw some more light on the requirement, we might be able to help you better.
ASP.NET is not the right place to house your Scheduled Tasks. I'm using Quartz.net when I have to create Scheduled Tasks.
Create a page that launches your task and place it at the URL http://www.mydomain.com/runtask.
Create a scheduled task on your home PC that sends a request to http://www.mydomain.com/runtask.
You'll need to keep your home PC on all the time.
Ideally I would go with number 1 as you get full control/history/error reporting etc. You can write an SSIS job in .NET and have SQL server schedule it.
However, I have had a similar problem with shared hosting that is very restrictive. What I did was create a page which runs the process on page load (using validation in the querystring for security). I then used a machine I have which is always on to schedule a Windows Task Scheduler (this is part of Windows as standard) to call a bit of VB script that opens the browser and then shuts it.
I am developing a solution in .Net utilising the VMWare Web Service API to create new isolated virtualised development environments.
The front end will be web based. Requestors input details for the specific environment which will be persisted to SQL. So I need to write an engine of some sort to pull the data from SQL and work on the long running task of creating resource pools, switch port groups and cloning existing VM templates etc. As work progresses, events will be raised to write logs and update info back to SQL. This allows requestors to pull data back into a webpage to see how it's progressing or if it's completed.
The thing I am struggling with is how to engineer the engine which will exec the long running task of creating the environment. I cannot write a windows service (which I would like) as we work in a very secure environment and it's not possible (group policy etc). I could write a web service to execute the tasks, extending the httpRuntime executionTimeout to allow the task to complete. But I'm keen to hear what you guys think may be a better solution to use (based on .Net 3.5). The solution needs to be service oriented as we may be using it on other projects within our org. What about WWF, WCF? I have not used any of the newer technologies available since .Net 2.0 as we've only just been approved to move up from .Net 2.0.
First of all, a Windows Service isn't insecure. One of software development devils is discarding a solution by ignorance or because a lack of investigation, requirement analysis and taking decisions collaborately.
Anyway, if you want to do it in a SOA way, WCF is going to be your best friend.
But maybe you can mix a WCF service hosted by Internet Information Services and Message Queue Server (MSMQ).
A client calls a WCF service operation and enqueues a message to some Message Queue Server queue. Later, a Windows scheduled task executed overtime, checks if your queue has at least an incoming message, and task processes this and others until you dequeue all messages.
Doing this way, IIS WCF host will never need to increase its execution time and it'll serve more requests, while the heavy work of executing this long tasks is performed by a Windows scheduled task, for example a console application or a PowerShell cmdlet (or just a PowerShell script, why not?).
Check this old but useful MSDN article about MSMQ: http://msdn.microsoft.com/en-us/library/ms978430.aspx
I don't understand your comment regarding services being insecure, I think that is false.
However I would look into creating something that uses a messaging bus/daemon.
RabbitMQ: http://www.rabbitmq.com/
MassTransit: http://masstransit-project.com/
NServiceBus: http://nservicebus.com/
Then you can basically use something like WCF, Console App or Service as your daemon.
Are there situations that we should use a windows service ?
I am building a client-server project (c#) and the server supposed to work alone without any user so someone advised me to use a windows service to run the server, is this right ? or there are a better solutions ?
Windows services are normally used when an application needs to continuously run. For example if they need to:
Wait for incoming requests. (Like through remoting or wcf)
Monitor a queue, file system etc.
If a program just needs to run periodically, like once a day. It is normally easier to create a scheduled task.
In your situation I would use a service for the following reasons:
You don't need to have a session running. This is good for security, and also reduces overhead on the server.
You get some of the managment commands built in for free
Start
Stop
Pause
Continue
You can handle server events such as shutdown.
Windows service can start running as soon as the machine is powered up, which makes ideal for running as a server, http server for example. No one is required to login.
You should create a Windows Service to run code in the background, without user interaction.
For example, a Windows Service will run even if no-one is logged on.
Any server that accepts connections (such as a mail, web, or FTP server) should usually be a Windows Service.
Well, a Windows Service provides a full framework for your application to work and to remain active while you want it to, so I think its ok.
Windows services are the right thing to use for something that should run all of the time, whether or not a user is logged in.
If you need something to run without an active user logged in, you need to use a windows service.
When you need the application to start running even when no one has physically logged into the machine, which is common with server machines, a service is a good candidate in this case. Especially because the service can be configured to auto start, which means the service will start when the machine is rebooted withut human intervention.
If however you are wanting to host web services (WCF) while a service is an option, you might consider hosting in IIS, this relieves you of writing the actual hosting code etc.
I need to implement a background process that runs on a remote windows server 24/7. My development environment is C#/ASP.NET 3.5. The purpose of the process is to:
Send reminder e-mails to employees and customers at appropriate times (say 5:00PM on the day before a job is scheduled)
Query and save GPS coordinates of employees when they are supposed to be out on jobs so that I can later verify that their positions were where they were supposed to be.
If the process fails (which it probably will, especially when updates are added), I need for it to be restarted immediately (or within just a few minutes) as I would have very serious problems if this process failed to send a notification, log a GPS coordinate, or any of the other tasks its meant to perform.
Implement your process as a Windows service.
For a straightforward example of how
to code a Windows service this in
.Net see http://www.developer.com/net/csharp/article.php/2173801 .
To control what happens should the
service fail configure this through
the "Recovery" tab on your service
in services.msc. (see image below)
For higly critical operation you
might look into setting up a server cluster for mitigating single
server failure (see http://msdn.microsoft.com/en-us/library/ms952401.aspx ).
(source: microsoft.com)
You need a Windows Service. You can do non-visual iterative operations in windows services.
Another alternative is to create a normal application and run it on a schedule. Your application is run at certain times a day to perform its actions, depending on how often you need to log GPS coordinates and send reports. If your service doesn't need to run constantly this is usually the recommended approach, as services are supposed to be limited to always-on applications.
As well as being a service, you might want to run on a cluster, and make your service known to the cluster management software.
You can create Windows Service (server programming on Windows) or use scheduler to periodically execute a task.
Depending on the requirements for the high availability, program can be installed on a fail-over cluster where there will be other server (passive node) started and quietly waiting as a hot-backup if the first (active node) dies. This is wide topic. Start with High availablity on Wikipedia.
In my experience if you need to run something 24x7 you need to have (one or more) watchdog process to verify that your service(s) are running correctly. Just relying on the normal service framework cannot guarantee that the program is working correctly - even if it looks like it is running. The watchdog program (which also is a service) can query the service automatically e.g. posting messages checking response times, querying for statistics and so on - when it detects problems it can restart the service (or do some other fail-recovery)
The reason for having a watchdog program as opposed to just rely on user queries to detect errors is that it can be done automatically. This is the preferred method because it allows for a proactive detection.
Scenario: A WCF service receives an XDocument from clients, processes it and inserts a row in an MS SQL Table.
Multiple clients could be calling the WCF service simultaneously. The call usually doesn't take long (a few secs).
Now I need something to poll the SQL Table and run another set of processes in an asynchronous way.
The 2nd process doesn't have to callback anything nor is related to the WCF in any way. It just needs to read the table and perform a series of methods and maybe a Web Service call (if there are records of course), but that's all.
The WCF service clients consuming the above mentioned service have no idea of this and don't care about it.
I've read about this question in StackOverflow and I also know that a Windows Service would be ideal, but this WCF Service will be hosted on a Shared Hosting (discountasp or similar) and therefore, installing a Windows Service will not be an option (as far as I know).
Given that the architecture is fixed (I.E.: I cannot change the table, it comes from a legacy format, nor change the mechanism of the WCF Service), what would be your suggestion to poll/process this table?
I'd say I need it to check every 10 minutes or so. It doesn't need to be instant.
Thanks.
Cheat. Expose this process as another WCF service and fire a go command from a box under your control at a scheduled time.
Whilst you can fire up background threads in WCF, or use cache expiry as a poor man's scheduler those will stop when your app pool recycles until the next hit on your web site and the app pool spins up again. At least firing the request from a machine you control means you know the app pool will come back up every 10 minutes or so because you've sent a request in its direction.
A web application is not suited at all to be running something at a fixed interval. If there are no requests coming in, there is no code running in the application, and if the application is inactive for a while the IIS can decide to shut it down completely until the next request comes in.
For some applications it isn't at all important that something is run at a specific interval, only that it has been run recently. If that is the case for your application then you could just keep track of when the table was last polled, and for every request check if enough time has passed for the table to be polled again.
If you have access to administer the database, there is a scheduler in SQL Server. It can run queries, stored procedures, and even start processes if you have permission (which is very unlikely on a shared hosting, though).
If you need the code on a specific interval, and you can't access the server to schedule it or run it as a service, or can't use the SQL Server scheduler, it's simply not doable.
Make you application pool "always active" and do whatever you want with your threads.