I use NLog's WebService target in Silverlight and run into a problem if the logging service is unavailable.
What happens is that all calls to the logging service hang for a long time until they time out.
This is firstly ugly and secondly problematic in the face of a request limit, which I have under my given circumstances. After the request limit is reached due to several pending logging requests, the application also fails to make requests that are not logging related.
Ideally I'd like a WebService target that sends the requests sequentially, but I can't configure it to do that, can I?
Since I have full control about the logging server I could also move to a different target, but I'd rather have a purely configuration-based solution.
Some time back I implemented a logging target like that for Silverlight. We were using Common.Logging for .NET and it did not support Silverlight. So, we ported part of Common.Logging to Silverlight and implemented a "logging service adapter" to send our logging messages to a logging service. I implemented a logging queue using the producer/consumer pattern. Maybe you will find it useful.
In the end, the project that I was working on when I implemented this didn't go anywhere, so this particular piece of code is not in use.
Using WCF service via async interface from worker thread, how do I ensure that events are sent from the client "in order"
Related
I am developing an application and decided Nagios3 for performing monitoring stuff. But I am stuck at two points. I am using check_http plug-in for monitoring load on my service api. Now I want to perform below tasks.
I need to set a threshold in check_http for performing some task after crossing that threshold. I tried below command
'check_command check_nrpe_1arg!check_service_api'
but it only tells me the load, not any threshold is set. while below one doesn't work.
'check_command check_service_api!100!200'
I need to send simple text message on some port(my application).
I am new to Nagios, so please help me figuring out the solution except email notification stuff.
There is a check command that you can download called "notify_sms" that integrates with an API server hosted by a company called Esendex. They charge for their service but it works well.
What is the correct way of handling errors on the client side of Silverlight applications? I tried building a service endpoint that would receive details about the error and then would write that string to the database. The problem is, the error's text exceeds the maximum byte length, so I can't send the exception message and stacktrace. What would be a better way of handling errors that end up at the client side?
Try handling faults...I used this pattern from MSDN
http://msdn.microsoft.com/en-us/library/dd470096%28VS.96%29.aspx
If you find you message is too long to send to your logging web service then try setting your binding properties such as maxBufferSize and maxStringContentLength to appropriately large values. They default to 16KB, personally i have set mine to 2147483647 (which is int.MaxValue).
Obviously you cannot send the raw exception straight to the logging web service (exceptions are not serializable), what i did was write a function that takes an exception and walks it, translating it into a WCF friendly structure that can then be passed to my logging end point. Of course you need to ensure that if this fails you have a backup plan, like maybe logging it to isolated storage if you are running in browser, or logging it to the user's file system if you are running elevated OOB.
You should not be considering logging of error messages via a service. What if the error that you want to log is related to the service itself? Maybe the server that hosts all dependant services (including the error logging service) is not reachable or down. client errors should be logged on the client side and periodically flushed to the server when connectivity to service is available.
Thats what I would do...
Take a look at the new Silverlight Integration Pack for Enterprise Library from Microsoft patterns & practices. It provides plumbing for both logging (client-side and via a remote service) and exception handling with flexible configuration of policies via config or programmatically.
The scenario:
I have a PRISM application developed in Silverlight (4), and I'm using a ASP.NET server side application to host several web-services (which, in turn, accesses WCF-services, but that's not really important here). The Silverlight application must be able to call the web services cross-domain (meaning that the web services isn't necessarily on the same server hosting the silverlight application).
The Silverlight application consists of several modules, each accessing the ASP.NET web-services.
I do not have much experience with Silverlight and PRISM, but as far as I can see, this is not a very unusual scenario...
The problem:
My challange is, that when 2 different modules access the web-services, I get 2 new sessions on the web-server. I would have thought that since both modules live on the same HTML-page (and then also in the same browser session), they would get the same session on the web-server...?
I have tried to make the web-service Proxy-client globally available in the container (using Unity), by registering an instance (using Container.RegisterInstance), and then getting this instance whenever a module needs to make a web-service call (using Container.Resolve), but this doesn't seem to help.
However, any calls made within the same module always gets the same session on the server.
Can anyone see what I'm missing here...?
Thanks!
Jon
Looks like I found my own answer.
The problem was that my application was firing multiple web-service calls upon startup (the different PRISM-modules working independently). And when several calls were made before any responses was given from the web-server, no session (and hence no "ASP.NET_SessionId" cookie was provided) back to the client before subsequent calls were made.
My solution was to make sure I make one call (async as always), for example to a simple Ping-like web-service, then hold all other calls to the web-server until this response is back. Then, all subsequent calls are given the same Session on the server (because now they all contain the "ASP.NET_SessionId" cookie in the header).
In pratice, this call is made by the PRISM-shell, and no modules are beeing loaded before I receive the reponse. Then I'm absolutely sure that none of the other modules get trigger-happy before I have a session-state on hand.
Still, if anybody sees any other problems with this solution, I'm more than happy to hear from you.
Thanks!
Jon
Can anyone think of a good way to allow the server to notify the client based upon server processing? For example, consider the following events:
A user requests a deletion of data, however, due to it's long-running time, we kick it off to a queue.
The client receives a "Yes we completed your transaction successfully".
The server deletes the item and now wants to update any local structures any clients may be using (I'd also like to notify the user).
I know this can be done by client-side polling. Is there a event bus type way to do this? Any suggestions are welcome, but please keep in mind I am using GWT with App Engine.
The standard AJAX interaction is that the client sends requests to the server and expects some sort of response back fairly quickly.
In order for the server to initiate a request to the client, you will need to use WebSockets, and experimental HTML5 feature currently only supported by Chrome.
Or, to simulate this kind of interaction, you can use Comet (long-polling), made available in GWT by the rocket-gwt project.
You want server events for GWT? Have a look at GwtEventService (they couldn't have chosen a better name): http://code.google.com/p/gwteventservice/wiki/StartPage
Of course, it uses a Comet implementation, but you can't do any different when using HTTP, the client always initiates the communication. Request, response.
In ASP.NET, I usually log exceptions at server-side, In windows forms I can either log exceptions server-side or write to a log file on the client. Silverlight seems to fit somewhere in between.
I wanted to know what everyone else is doing to handle their Silverlight exceptions and I was curious if any best practices have emerged for this yet.
For real logging that you could store & track, you will need to do it on the server, since you can't be guaranteed anything on the client will be persisted.
I would suggest exposing a "LogEvent(..)" method on a server side web service (maybe you already have one) which would then do the same kind of logging you do in ASP.net
Here's a video about basic web service calls in Silverlight if you haven't done that yet
http://silverlight.net/learn/learnvideo.aspx?video=66723
I'm not sure about any logging best practices though, my first guess would be to do the best practicies for logging in a web sevice on the server and expose that to the client.
Hope this helps!
I would say that Silverlight fits much better to ASP.NET side of the model. You have server which serves web page. An object (Silverlight app) on the page pings data service to fetch data and display it.
All data access happens on the server side and it does not matter if data is used to create ASP.NET pages on the server or sent raw to the RIA for display. I do log any failures in data service on server side (event log works fine) and do not allow any exception to pass to WCF. When client does not receive expected data (it gets null collection or something similar), it display generic data access error to the user. We may need to extend that soon to pass a bit more information (distinguishing between access denied/missing database/infrastructure failure/internal error/etc), but we do not plan to pass exception error messages to the client.
As for client side, sometimes we may get in situation where async call times out -- it is just another message. For general exceptions from client code (typically, bugs in our code), I just pass exception to the browser to display in same manner as any script exception.
Also take a look at the new Silverlight Integration Pack for Enterprise Library from Microsoft patterns & practices. It provides support for logging exceptions to isolated storage or remote services and is configurable via policies in external config or programmatically. Batch logging and automatic retry (in case of occasionally connected scenarios) are also supported.
Use the Isolated Storage available for Silverlight application. You should store here your log.
Then you can develop a mecanism to send the user log to a webservice like the Windows bug report service.
It very much depends on the type of application that youre developing.
if its an mvc / mvp based architecture then your model, or most of it at least, will be on the server, and this is where most of your exceptions will be thrown i would imagine, so you can log them there and choose to display a message to the user or not.
for exceptions from the client you may want to know the details so just send them back.