We have a multi-system solution: several web sites and a separate App-Tier implemented / exposed as WCF services. The web sites all use EntLibs to log stuff - but they need to log to a central DB which is only accessible by the App-Tier.
To get around this we're looking at implementing a WCF service that can have LogEntires sent to it (via a Custom Trace Listener that sends the Log Entries to it).
The decision to use a WCF service is that it's in keeping with the rest of the architecture - and we don't have a lot of time to go doing much else.
I also looked at this and started wondering if we're on the wrong track altogether (from a performance perspective).
So, my question is:
Is this such a bad idea that I should just stop?
If it's viable, what are the traps I need to look out for?
The answer in the question you linked to covers it quite well, if you read between the lines:
Call the WCF logging service with "Is One way" = true, so that your client program does not wait for the logging to complete.
Set the WCF settings such that the client does not throttle the number of requests
Related
We are planning to redesign our services to micro services using service fabric, I have some questions that I hope you can help me with, here we go:
Communication Stack
All our services are on WCF using net.tcp so in theory we can reuse the WCF Communication stack but I'm not sure that's the best way, what are the differences between the default communication stack and the WCF one?
Extensibility
We have a lot of implementation using the extensibility points of WCF, if we choose the WCF communication stack can we still use this? We are basically using IServiceBehavior,IOperationInvoker, OperationContext and ServiceSecurityContext for this:
1. Security ServiceSecurityContext/OperationContext to get the IP and if the call is in the intranet the domain account who is making the call, I checked in StatelessServiceContext but could not find any property where i could get this info.
2. Parameters and time IOperationInvoker to log the parameters of the method and how much it took to finish the operation, reading this it appears that if implement the Start/Stop methods the time duration is done automatically, what I'm not sure is if this will work in the context of an attribute and with IErrorHandler when an error happens.
3. Notifications IErrorHandler to log the exception and then send an email to the developer team, we are currently doing this using an SMTP server, is there a better way to send notifications in azure?.
Thanks for your time
Answering this:
Communication Stack
Never did a comparison in performance between the default listener and WcfCommunicationListener but we opted for WCF to reuse all our components and as a first version to understand how service fabric works.
Extensibility
Security All the code worked the same, we needed to make some changes to the way the context works, but all the info needed was there (plus some data on the node it was running)
Parameters and time We used Azure Service Profiler with our own implementation of Microsoft.Diagnostics.Tracing.EventSource capturing the data using IOperationInvoker, awesome
Notifications IErrorHandler continued to work but we used sendgrid for the emails.
So I'm looking into implementing NServiceBus in our current setup and just trying to get a better understanding of how things should be setup.
Our current setup consists of multiple clients (websites, scheduled tasks, etc..) calling a WCF service we have set up for handling the sending of emails. Of course, if the service goes down then our clients start getting errors and all of those messages are then lost (one of the reasons we want an ESB).
I've seen how you can configure your WCF service to handle nservicebus messages in a pub/sub setup. What I'm not sure on is what is the best way to set it up.
Setup 1:
Client (Publisher) -> NServiceBus handler (Subscriber) -> WCF Service
In this case, to scale you'd increase the number of handlers (hosted nservicebus services?), keeping just the one WCF service.
Setup 2:
Client (Publisher) -> WCF Service (Subscriber)
This one you just increase the number of WCF services to scale (updates would be a nightmare).
I just started looking into the ESB architecture in general so if I'm completely off let me know. I'm essentially just wanting to know what is working for you, and what the "best practice" tends to be.
Thanks!
I'm not completely clear on what you need WCF for anymore if you implement this via NServiceBus. Is the WCF component required for anything besides receiving messages (to send an email) from the multiple clients? If not, you could remove WCF from the equation.
From the sound of it, you will also want the Service to act as a single logical endpoint that handle requests to send emails. If that's the case, you will want to use Send (a command) instead of Publish (an event). Publish is used to broadcast an event, which means that something happened already; Send is used to instruct another component to do something. It sounds like you want the latter.
Scaling of an endpoint can be done via the Distributor. This may or may not be useful depending on where you expect the bottleneck to be.
Edit: Based on your comment, I would simply go with the second setup, and just add the handler to the WCF service. If you are hosting WCF in IIS, make sure you have something that wakes the process up if the app pool recycles (the incoming message won't wake it up the same way an incoming request to WCF will).
We do something similar internally where one NSB endpoint handles all the sending of email. The clients can either use NSB directly to Bus.Send() the command to send a message to the email endpoint or you can expose that endpoint via WCF as well (only to get the commands over to the endpoint). Once the endpoint has the commands, they would just call your existing service to maintain compatibility with your existing clients.
I'm evaluating the WCF Data Service approach for my next project. As I would need to be flexible on logging and authentication I have a couple of questions that maybe you are able to answer.
1) Am I able to log different level of events, ex. warnings, errors, and redirect them to a different logging sources as database, text file, event log?
2) A link that shows how to perform the requested on question 1
3) Is there a way to introduce a simple authentication based on user name and password and how it is done?
4) Do you have by direct experience discovered any limitation on using Data Services instead of creating a WS-* WCF service for what concerns logging and authentication?
Thanks
There's a good series of blogs about auth over OData service here: http://blogs.msdn.com/b/astoriateam/archive/tags/authentication/
For logging you should be able to use your web server's logging facilities (typically IIS I assume), since all errors are reported as error responses by the service.
You can also override the DataService.HandleException method and implement your own logging in any way you want.
For logging of general non-error things there's also the processing pipeline (DataService.ProcessingPipeline). You can register a handler and implement your own logging of these as well.
I don't know of a sample of this tough.
Folks,
I'm building a pretty standard workflow that I want exposed via a WCF endpoint - I'm using the "WCF Service Application" project template and I've got a .xamlx service. This is a very simple document interchange workflow service - I want consumers to POST me a blob of XML as the body of an HTTP post (with HTTP headers containing authentication tokens). In response, these consumers will get a blob of XML containing the reply. 2 goals for me using REST/POX here are the document/message-based nature of the interaction AND I want to make client development easy for non-.NET environments (especially limited environments like Silverlight and iPhone).
I don't really see how to make this possible using out of the box features (unless I'm missing something). Does anybody know how to create a RESTful (or even REST-ish, I'm not picky) endpoint for a WF4 service-hosted workflow? Any info leading in the right direction here would be great.
There is an unreleased item on CodePlex to cover this, which includes source code. Also see this SO answer which contains another idea for achieving this.
If you'd like to see the CodePlex activity released, please up-vote the UserVoice request.
Using a REST Pass-Through Service
As #Maurice mentions, you can also treat the WF service as a back-end service and expose a REST service that simply calls through to the WF service.
This method is a bit clumsy, but has the advantage that it doesn't use anything unreleased or really complicated.
If the back-end service runs on the same machine as the REST service (which is probably what you'd do), you should expose the WF service using the named pipes binding. This binding is fast, but only works when the caller and callee are on the same box.
A further thought: your REST pass-through service is blocked while the back-end service is being called. If your WF service is not very fast, you'd benefit from making your REST service asynchronous so it doesn't block a thread pool thread while the WF service is being called.
There are no out of the box activities that will allow you to use REST with WF, the Receice is pure SOAP.
You can either build a custom REST Receive activity and use that with your workflow. Depending on your needs this is going to be quite a handful to a lot of work. The easy option is use use a standard REST WCF endpoint and convert the REST data to SOAP, pass rhe request on to the workflow, and do the reverse on the result message.
While making my first ajax attempts, I decided also, to go to use IIS hosted WCF now. The strange thing is, that the WCF cannot process several requests parallel for the same user/session, if sessionmode is enabled! If sessionmode is disabled on asp.net, the requests are processed parallel. The broser/client may execute several different requests, where some of them are long running. This blocks all further requets and make my ajax app unusable.
This applies to asmx [webservices] also. I had a big hope, to compile the webservice methods using "IReadOnlySessionState" interface, but this has - in oppsite to webpages - no influence. But I need access [most times readonly] to the asp.net session!
Does someone knows any solution to this problems.
Anyway, thanks a lot!
br--mabra
In .NET 4, you can do this in Application_BeginRequest
if (Context.Request.Path.EndsWith("xxx.svc"))
Context.SetSessionStateBehavior(SessionStateBehavior.ReadOnly);
I found this:
http://blogs.msdn.com/silverlightws/archive/2009/09/30/having-a-pollingduplex-service-and-any-other-wcf-service-in-the-same-website-causes-silverlight-calls-to-be-slow.aspx
Which states,
"All WCF services require read/write session state access if you enable ASP.Net sessions, which causes the replies to be queued sequentially. Ideally user should be able configure the WCF handler to be read only, which would allow polling duplex services to work with sessions. Unfortunately this is unsupported at this point."
...the only thing I can think of is if there's some way to manually force early release of the lock. I'm looking into that now.
You can provide a custom session state provider
See: http://koolsand.blogspot.com/2010/02/why-iis-hosted-wcf-services-does-not.html
whenever a request contains svc in the
path it intimates default session
state provider to use readonly lock
and not read-write lock. So using
readonly lock will allow the next wcf
call to be executed concurrently.