I am using SoapExtensionReflector to modify the WSDL sent to the client due to a complex proxy setup. This modification is based on a query string variable:
whatever.com/Service.asmx?WSDL&customaddress=proxy.whatever.com
This works well, and the modification is successful. However, the WSDL is cached by ASP.NET the first time, so a second call to, say...
whatever.com/Service.asmx?WSDL&customaddress=dohicky.whatever.com
will still use the variables from the original call. I would like to disable WSDL caching and force ASP.NET to reprocess the WSDL every time. Is there an easy way to do this programmatically?
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I have two Asp.Net web apps, App 1 and App 2. They both use the same database. I am trying to give command from App 1 and immediately run a bit of code in App 2.
The only way I can think of doing this is by inserting a command in the database and have App 2 poll the database every few minutes. But this means there may be a delay in running the code.
Is there a way to run code in App 2 immediately?
You can fire an HttpRequest from one app to another and the code will run almost immediately.
I don't know what language and platform you're using, so it's hard to give you concrete examples, but here are the outlines:
Create a page in App2. In standard ASP.Net, you can use a handler. In ASP Core, you can use an API controller. Both car return a single value or a full object in JSON or XML. Or you can use a standard page if you like to return HTML. The code behind is what you want to run. The rendered page or return value from the handler or controller is what you want App1 to get back in response.
Then from App1, issue an HttpRequest to that page in App2 and check the response to see how to continue (for example, if the code ran successfully or not).
The HttpRequest is in case you want to make the call from the server side of App1. If you want to make the call from the client side, then you use Ajax instead. In the case of Ajax, you have to pay attention to the security side, because you don't want to allow whoever to call that page from App2 unless it unless the code behind doesn't pose any security risk and doesn't return any sensitive data.
One last idea specific to your scenario, since both apps are using the same database, you can add the required values to the database as you were planning to do, and then issue a simple HttpRequest. This way, you don't need to worry about security or passing a any sensitive info. When App2 receives the request, it checks the database to see if the request was actually made from App1 and then processes it, otherwise ignores it.
I have a public web app that calls ASP.NET web method in an ASMX file, located in the same site folder in IIS. But, to prevent bots to ping the service directly, we'd like to secure the API so that only our HTML 5 client page can access it. Do you have a suggestion on how should I implement this kind of thing ? Not too much, just a simple mechanism that won't take a week of testing please. Doesn't have to be a 100% full proof method since it is public data and the API just pumps data out, not inserting anything. Just something to limit possibilities of DDOS attack on the API.
The way I've tackled this in the past is with a custom header.
Essentially if your web page is using some form of AJAX call to call back to your services layer, then you can use something like:
xhr.setRequestHeader('custom-header', 'value');
where 'xhr' is an XML Http request that you've built in Javascript
of course you could also take the much easier route of just adding a parameter to your calls query string, EG:
in your ajax call, request:
http://my.services/service.asmx?somesecretkey=foobar
instead of just
http://my.services/service.asmx
Then you can just use the request's query string collection server side to see if it's present or not, and refuse the connection if it's not.
You could even go so far as providing some seed value in the data passed to the page in the first place, then use that seed value to create a unique value (one the server can also calculate) that is returned back in your request to the server.
Doing it that way would provide a slightly higher level of security, as the values would be semi random and not easy for a bot to guess.
Bear in mind also, that if you control the calling page, and you are doing this by ajax, you can also put this key in your post variables collection too so it doesn't have to be visible in the get request.
Other than using a web service, is there anyway to call a method in a web app from a windows application? Both run on the same machine.
I basically want to schedule a job to run a windows app which updates some file (for a bayesian spam filter), then I want to notify the web app to reload that file.
I know this can be done in other ways but I'm curious to know whether it's possible anyway.
You can make your windows app connect to the web app and do a GET in a page that responds by reloading your file, I don't think it is strictly necessary to use a web service. This way you can also make it happen from a web browser.
A Web Service is the "right" way if you want them to communicate directly. However, I've found it easier in some situations to coordinate via database records. For example, my web app has bulk email capability. To make it work, the web app just leaves a database record behind specifying the email to be sent. The WinApp scans periodically for these records and, when it finds one with an "unprocessed" status, it takes the appropriate action. This works like a charm for me in a very high volume environment.
You cannot quite do this in the other direction only because web apps don't generally sit around in a timing loop (there are ways around this but they aren't worth the effort). Thus, you'll require some type of initiating action to let the web app know when to reload the file. To do this, you could use the following code to do a GET on a page:
WebRequest wrContent = WebRequest.Create("http://www.yourUrl.com/yourpage.aspx");
Stream objStream = wrContent.GetResponse().GetResponseStream();
// I don't think you'll need the stream Reader but I include it for completeness
StreamReader objStreamReader = new StreamReader(objStream);
You'll then reload the file in the PageLoad method whenever this page is opened.
How is the web application loading the file? If you were using a dependency on the Cache object, then simply updating the file will invalidate the Cache entry, causing your code to reload that entry when it is found to be null (or based on the "invalidated" event).
Otherwise, I don't know how you would notify the application to update the file.
An ASP.NET application only exists as an instance to serve a request. This is why web services are an easy way to handle this - the application has been instantiated to serve the service request. If you could be sure the instance existed and got a handle to it, you could use remoting. But without having a concrete handle to an instance of the application, you can't invoke the method directly.
There's plenty of other ways to communicate. You could use a database or some other kind of list which both applications poll and update periodically. There are plenty of asynchronous MQ solutions out there.
So you'll create a page in your webapp specifically for this purpose. Use a Get request and pass in a url parameter. Then in the page_load event check for this paremter. if it exists then do your processing. By passing in the parameter you'll prevent accidental page loads that will cause the file to be uploaded and processed when you don't want it to be.
From the windows app make the url Get request by using the .Net HttpWebRequest. Example here: http://www.codeproject.com/KB/webservices/HttpWebRequest_Response.aspx
I want to implement an ISAPI filter like feature using HttpModule in IIS7 running under IIS Integrated Request Processing Pipeline mode.
The goal is to look at the incoming request at the Web Server level, and inject some custom HttpHeaders into the request. (for ex: HTTP\_EAUTH\_ID)
And later in the page lifecycle of an ASPX page, i should be able to use that variable as
string eauthId = Request.ServerVariables["HTTP\_EAUTH\_ID"].ToString();
So implementing this module at the Web Server level, is it possible to alter the ServerVariables collection ??
HttpRequest.ServerVariables Property is a read-only collection. So, you cannot directly modify that. I would suggest storing your custom data in httpcontext (or global application object or your database) from your httpmodule and then reading that shared value in the aspx page.
If you still want to modify server variables, there is a hack technique mentioned in this thread using Reflection.
I believe the server variables list only contains the headers sent from the browser to the server.
You won't be able to modify either the HttpRequest.Headers or the HttpRequest.ServerVariables collection. You will however be able to tack on your information to any of:
HttpContext.Current.Items
HttpContext.Current.Response.Headers
Unfortunately, Request.Params, Request.QueryString, Request.Cookies, Request.Form (and almost any other place you'd think of stuffing it is read only.
I'd strongly advise against using reflection if this is a HttpModule you're planning on installing into IIS 7. Given that this code will be called for (potentially) every request that goes through the web server it'll need to be really fast and reflection just isn't going to cut it (unless you have very few users).
Good luck!
Our web services are distributed across different servers for various reasons (such as decreasing latency to the client), and they're not always all up-to-date. Rather than throwing an exception when a method doesn't exist because the particular web service is too old, it would be nicer if we could have the client check if the service responds to a given method before calling it, and otherwise disable the feature (or work around it).
Is there a way to do that?
Get the WSDL (append ?wsdl to the URL) - you can parse that any way you like.
Unit test the web service to ensure its signatures don't break. When you write code that breaks the method signature, you'll know and can adjust the other applications accordingly.
Or just don't break the web services and publish them in a way that enable syou to version them. As in http://services.domain.com/MyService/V1.1/Service.asmx (for .NET) so that way your applications that use v1.1 won't break when you publish v1.2 and make breaking changes.
I would also check out using an internal UDDI server if it's really that big of a hasle to manage your web services. Using the Green Pages of UDDI will tell you what you want to know about the service.
When you are making a SOAP request you are just sending an HTTP request to a server. If the server understands it, it will respond with an HTTP 200 and some XML back, if it doesn't it will send you some error HTTP code (404, 500, ...)
There is no general way to ask for the existance of a "method" exposed by a web service. Try to use the WSDL exposed if it is automatic, or just try to use the "method" and check for an error in the response (you don't have to send an exception to the user...)
Also, I don't know if I understood you well, but you are thinking of quering the server twice, once to check if the method exists, and second to make the actual call it if it does? I would just check for the error if it doesn't, and proceed normally if it does.