I understand that MSDTC(Microsoft Distributed transaction coordinator) WCF uses to manage its distributed transaction but If WCF service perform some database operation on Oracle or File System will this same coordinator will work and if no which it will be and can we choose wcf coordinator for our wcf service
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We are looking at using ActiveMQ as the message transport with NServiceBus, instead of MSMQ, to enable Java endpoints to directly integrate with .NET endpoints over ActiveMQ.
By default NServiceBus endpoints run in a distributed transaction involving MSMQ and SQL Server. Is there the same level of support for distributed transactions in NServiceBus when the message transport is ActiveMQ? Are there any other drawbacks to using ActiveMQ with NServiceBus as compared to MSMQ?
We've actually uncovered issues with the .net client of ActiveMQ - it doesn't support distributed transactions well enough. While we've tried to work with the committers over there, we still haven't been able to get this fully resolved.
At this point in time, if you want to use ActiveMQ on .net (with or without NServiceBus) you'll have to take care of deduplicating any messages flowing through your system.
We're working hard to build this kind of infrastructure-level deduplication logic into NServiceBus such that queues like RabbitMQ and Azure Service Bus that don't support distributed transactions give the same behavior as MSMQ.
From the book Learning NServiceBus by David Boike:
Like MSMQ, ActiveMQ supports the DTC which ensures that our message handlers remain fully transactional.
As far as drawbacks go:
ActiveMQ server does not support DTC transactions for deferred messages.
Other issues are reported on the NServiceBus.ActiveMQ GitHub site. I recommend perusing the list.
We have set of WCF services running on single computer which collectively serves an WPF application which could be on same machine or on remote machine (within same network only). We need failover mechanisum so whenver any of the service crashes or hangs - we want to restart the service and initialize it by calling appropriate method.
Since we are not aware of what is the industry standard for implementing failover for WCF service - we have implemented like this way. We start main WCF service hosted in console app along with one more secondary WCF service which constantly checks health of main WCF service by calling exposed method on given endpoint. If main WCF service fails, it takes role of main WCF service and launches another secondary WCF service.
The above approach is working fine but only problem we have seen is memory since we launch services in pair and every host requires 10MB of memory.
Can anyone help me what is the industry practice for implementing failover for this kind of scenario?
I am using WCF in Wan.The basic activity of WCF is Database Synchronization.
Therefore the performance is critical.Currently I am using wsHttpBindings.
Is there any other optimized option which shall survive the Wan and Latency Options?
I have a WCF service that all clients connect to in order to get notifications \ reminders (using a CALLBACK interface they implement). Currently the WCF service is self-hosted, but the plan is to have it hosted in a Windows Service.
The WCF service has a 'Publish', 'Subscribe' and 'Unsubscribe' operations.
I need to have a background worker thread of some sort poll an SQL server database table constantly [every XXX minutes], and look for certain 'reminder' rows. Once it finds them - it should notify all the connected clients.
I thought of 2 ways of achieving this.
.
METHOD A :
Have a separate EXE project (don't want it to be a console, so what should it be - a Windows Service ?) that will start and run a background thread. The background thread will connect to the 'Reminder' service as one of its clients. The background thread will poll the database, and once it finds something - it will send a 'Publish' message to the WCF service, that will make the WCF service send the reminder to all the subscribed clients.
.
METHOD B :
Somehow make the background thread run within the WCF service project, and when it detects a new reminder row in the database, somehow make it 'signal' the WCF service with the info, and the WCF service will then send this info to all subscribed clients.
.
Which method is better ? Any other suggestions ?
If this is a long running process, a windows service is the perfect solution.
Your main Win Service thread will be polling the DB, queuing the results into some kind of supplier/consumer thread safe collection.
You can host a WCF service within the win service, which can then consume (remove) any results from the queue and pass them back to the client as requested (calls into the WCF will come in on their own thread)
This is a pretty common architecture, and not difficult to implement.
Method A:
If you were to create two separate hosts (i.e. one for the WCF service and one for the "Polling" service) then you really have only one option to make it all work nicely.
Windows Service communication is very limited (without the help of a service endpoint, e.g. WCF). Therefor, if you were to host your "Polling" service in a Windows Service, you must couple it with a WCF service anyway.
It is then feasible to host both services together in one Windows Service and by manually instantiating the WCF host and passing into the constructor a "Polling" service.
protected override void OnStart(string[] args)
{
//...
// This would be you "polling" service that would start a background thread to poll the db.
var notificationHost = new PollingService();
// This is your WCF service which you will be "self hosted".
var serviceHost = new WcfService(notificationHost);
new ServiceHost(serviceHost).Open();
//...
}
This is far from ideal because you need to communicate via events between the two services, plus your WCF service must run on singleton mode for manual instantiation to work... So this leaves you with...
Method B:
If you were to host the "Polling" services inside your WCF service, you are going to run into a number of issues.
You need to be aware of the number of instances of the "Polling" services that gets created. If your WCF service has been configured to be instantiated for every session, you could end up with too many "Polling" services and that may end up killing your db/servers.
To avoid the first issue, you may need to set a singleton WCF service, which may lead to a scaling issue in the near future where one WCF service instance is not enough to handle the number of connection requests.
Method C:
Given the drawbacks in Method A and B, the best solution would be to host two independent WCF services.
This is your regular service where you have subscriber/unsubscribe/publish.
This is your polling singleton service with subscribe/unsubscribe.
The idea is that your regular service, upon receiving a subscriber will open a new connection to your polling service or use an existing one (depending on how you configure your session) and wait for a reply. Your polling service is a long running WCF service that polls your db and publish the notification to its subscribers (i.e. the other WCF host).
Pros:
You are assured that there will be only one polling service.
You could scale your solution to host the regular service in IIS and the polling service in Windows Service.
Communication limitations is minimal between the two services and no need for events.
Test each service interdependently through their interfaces.
Low coupling and high cohesion between the services (this is what we want!).
Cons:
More services means more interfaces and contracts to maintain.
Higher complexity.
I have a MSMQ queue and I need to implement a listener that is executed periodically or at specified time (i.e. nightly) to process messages in the queue.
WCF provides netMsmqBinding that allows sending messages to other service via MSMQ. I wonder is it possible to implement the WCF service to consume messages at specified time or periodically in equal intervals? Or WCF always consumes message as soon as it arrives?
For example I need to check queue every hour, and if there are any messages - process them.
One more question is about concurrency. Can I configure WCF service to use limited number of threads (e.g. 2) for queue message handling?
Thanks
Your best bet is to host the MSMQ consumer in a windows service and then configure a windows scheduled task to start it up and shut it down (eg with a powershell script) as per your service window requirements.
EDIT: I believe NServiceBus sagas can also support this requirement but it does not use WCF.