So I'm working on a project for my internship and have hit a bit of a brick wall. Unfortunately, the only people I know who are qualified to help me at the office are on vacation at the moment, and Google has been unfortunately unhelpful (or my search skills inadequate), so I thought I'd ask here.
The project is basically to make a server to mimic one that the company (which makes phone apps) already has. What I need to do is have one of their apps send a request to my server (I will have to modify the app to do this, but don't know how), and have my server reply with an XML response that the app already knows how to process. (The main purpose is so that we can see how the app responds when the real server sends it an error by simulating it on my server.)
Now, I already have a few sample HTTP requests and their associated XML responses handy, taken from simulations with the app and the real server. The app is written in C#, and currently sends HTTP web requests to the real server's online location, which responds to these HTTP web requests with XML. My server, however, will not have an online location, so the app will have to be modified to work with sockets on a local host.
My questions:
1) My boss said to create an XML file to associate certain requests with certain XML responses, but I have no idea what he means or how to do this. (He said it could also be done with a .ini file.) Does anyone know?
2) Once I have this XML file that can make these associations, how can I incorporate it into my server so that my server can check the request it received against its table of valid requests and figure out which response to send back?
3) How can one modify the app from using HTTP web requests and responses to using sockets?
If you have any questions/clarifications that you need in order to better answer this, please don't hesitate to ask me.
Thanks!
What you're describing is a web service. Unfortunately, his advice to change a setting in an .ini file make it sound like they have a proprietary system for doing this, rather than using a standard ASMX (which requires IIS) or WCF (which can either run in IIS or as a standalone service, which it sounds like is what you'd want) service.
Without more information about what they're using, I don't know that you'll be able to get much help here.
In response to question #3:
HTTP is a protocol that already runs on a specific socket (normally using port 80).
An internet socket is an endpoint that is used to transport data between processes. If you want to run your own protocol, you will need to create a new socket (with TCP or UDP) on a specific port.
This will however require you to create your own client and server in order to exchange data between them.
To get started, here is a very simple client-server example in C# using a custom socket.
Good luck!
Ask your boss if this client communicates with soap, if so then just go to MSDN and find tutorials on implementing an ASMX webservice, follow the tutorial through and you'll have a shell to start with.
First I'd like to say that it sounds like you have some unclear requirements that you should probably clarify with your boss. If you're not exactly sure what he means you should find out because nothing sucks more than having to support someone's creative interpretation of requirements.
1) It sounds like your boss just wants a way to easily change associations for testing without having to rebuild the app so he's asking you to store those associations in an xml/ini file that can easily be modified. In c# you can easily go between XML and DataSet objects so this should be trivial. I would create the data structure in a DataSet first and then use the GetXml method of the DataSet to output the xml format.
2) In .NET you can store objects in Cache and create a Cache Dependency that is a file association. Thus whenever the file is modified the Cache is purged. Whenever your program handles a request it pulls the object from Cache, if the object isn't in Cache then you have a condition block rebuild it from the xml/ini file on disk. I would have that condition block call out to a function that then loads the above mentioned xml format into a dataset that is then stored in the Cache with a Cache Dependency.
3) If you are trying to test an applications i/o, modifying it to use a different transport layer sounds like a bad idea. If the app currently works over HTTP to send requests then just route the HTTP request. I would suspect that the app probably has a configuration somewhere defining the path of the webservice it currently calls out to, once you know what that path is you can either change it, or if that's not possible setup a DNS rule on the server running the app to route it to the location of your application. On windows this is as simple as adding a line to the hosts file.
Related
First of all, I'm completely open to suggestions for alternative strategies, since this is not a space I'm hugely familiar with.
I have what I think is a simple problem. I have a client app and a server app, and I want to send a bunch of files from the client to the server. I don't want to require the user to set up file shares or anything, so my thinking was:
I'll have an app on the "server" using HttpListener to listen to file transfer requests from the client.
I'll have an app on the client using WebClient.UploadFile to initiate the transfers.
Twist: The server is a Mac, and I need to use things that are supported by Mono. I'm not looking to have the server install ASP.NET / IIS / whatever. In fact, the less the user has to do, the better. (The user in this case will be in control of both the client and the server, by the way.)
So, short questions:
Is there a better/easier way than WebClient/HttpListener to send a bunch of files from one machine on a LAN to another? TCP-something? Sockets-something-or-other? (You can see my ignorance.)
Assuming I use HTTP, are there more straightforward ways to download files than using an HttpListener and manually parsing the requests to get rid of headers, etc.?
I've some strange problems with a web service. One problem is that I don't fully understand how SOAP works.
It seems that it is possible that two different application can connect to e.g. 127.0.0.1:8000 at least that seems possible with the code that is generated with the .NET WSDL tool. But IMO only one application is allowed to bind to a port and listen to HTTP responses. Do the .NET classes do something silently?
For a tiny test I tried to do everything on my own with the HttpWebRequest class to see where the problem is. I get some 500 StatusMessages from the Webserver that the EndpointDistpacher is unable to find an AddressFilter (I think it's probably an .NET exception for the server transfered over HTTP). I copied the SOAP request from another client that works. What I here do not understand. Does the server probably open another new connection to the client, instead of answer to the already open connection?
I don't seek direct answers for my problems. What I really wonder how TCP/HTTP is used in the background for raw SOAP and for WS-Adressing. And what I've to do, to create a simple stupid client, assuming that I only have a TCP/HTTP class.
I would like to have a client application and web application (or service, no UI) and I would like to connect to said web service from within my desktop application and to have two simultaneous network stream, one of them for uploading data and reading them on server and the other one for sending stuff to the client application.
I am not looking for a solution that uses anything more than that like WCF or anything, I just want a way to create connection between web server and my client application and exchange pure binary data. I would implement the protocol myself, I am not looking for any entities or encapsulation like WCF provides.
I don't even know what project type is the best choice here. I thought about empty ASP.NET application maybe that I'd upload on FTP but I have no idea what I should do next to make the application connectible to. I am not asking for complete solution of course, rather some articles that focus on how to make a plain and simple connection between server and client. I want server to be able to immediately update client and vice versa, that's why I am looking for a way to have stream.
Edit: I may as well say that the service is meant to be placed on ASP.NET hosting and I don't know how ports work on these, if there are any restrictions or anything.
"Web service" and "Network stream" are incompatible concepts. Web-services are (ideally) stateless and disconnected - so they work regardless of how the underlying network works. Messages are exchanged only from client-to-server and are encapsulated in HTTP request/response pairs. Hence "web service".
If you want to exchange "pure binary data" (as you put it) then you just need to work with sockets (or use .NET's TcpClient, which wraps up sockets in an easier-to-use API). ASP.NET would be inappropriate for this.
You can technically have an application that uses sockets that runs within an ASP.NET host process but this might not work depending on how security is set-up and it's also bound by the ASP.NET process lifecycle (so it is activated by IIS and can be shut-down or recycled at any time without warning).
You do not want to use ASP.NET Web Services for this (ASMX). That is a legacy technology, and should not be used for new development.
Why do you not want to use WCF? Do you believe it's too complicated? The thing about WCF is that it removes the complication of creating your own protocols.
Also, which version of .NET are you using? WCF get a lot easier to configure with .NET 4.0.
Here is simple duplex example using WCF.
Try it, check if performance you've got is enough, try to use alternative bindings ( like net.tcp). WCF is really neat tool to use. Once become more familiar with it you will love it.
Also check chapter on bindings in WCF from Learning WCF
Have a look at the MVC4 APIController. It works much like stock MVC except that methods return XML or JSON (or anything else you like).
Eg
/api/Users/Get
would could return something like
{
{"Username":"Bob", "Id":3},
{"Username":"Steve", "Id":4}
}
You can also return files and other streams by using special return types. You even get strongly typed, validated input through the use of models.
There's an example here which shows a full CRUD controller and sample AJAX calls from JS which you can replicate in your desktop app
we're working on a peer to peer comm software that would allow a number of grocery stores to sync their inventory with what we call "headquarters".
To so this, we're thinking WCF+WPF, and no IIS and web services. My experience with WCF is basically zero, so my question is whether a TCP comm solution using WCF would work. The data that's being transferred is quite limited, about 2MB for a compressed plain text file (so we're sending binary data!), and this is done once per day only. So bandwidth/load shouldn't be an issue here.
The idea at this point is to have a WCF "server" running at HQ. Stores make themselves known to that server and then send files back and forth (simliliar to a chat application).
What I'm not sure of: does every store need to have a WCF "server" (or endpoint)? How would the server (=HQ) send a file to one of the clients (=stores)? Every store can send a file to any other store, and the HQ, and every store can also "request" a file from any other store/HQ.
Two limitations: None of the machines/computers involved can run Windows server for budget reasons, and as stated before IIS is a no-go.
If you are only sending files back and forth, I might question whether or not WCF even makes any sense. Have you considered just using a file transfer protocol, like scp or sftp?
Every machine will have to accept connections and have a file drop location setup, and then yuor application will have to monitor that location for new files. I love WCF in general, but a file transfer protocol is going to have a leg up if that is all you want to do.
If you direct all of your traffic via the server then there's no reason why you couldn't achieve this with WCF. The server would host WCF services in IIS with the stores having a client that was able to upload and request files. With this method, stores would not be able to directly transfer fiels to each other, but they would have to do it via the main server, which would suit your needs if you don't have the budget for the other scenario.
If all transfers are made once per day, the requests for files would be made with each client requesting what files they require, followed by each client uploading any files that are required by the server or any other client. The final step would be the server distributing the required files to each client. Obviously, this is a simplified view of it, the actual process may require some more thinking.
You don't need to host WCF in IIS, but is there any particular reason you don't want to do that?
You can host WCF in a ServiceHost, but then you need to build, maintain and deploy a lot of server/service features that IIS provides for free, such as application process recycling, activation-based hosting, etc.
In any case, it almost sounds like you need peer to peer networking. You can do that with WCF using the NetPeerTcpBinding.
If you have an opportunity to redesign your application, I suggest you do. You can throw strings around in WCF but if you can create a data contract you can keep all your communication strongly typed.
If you have access to windows server 2008 then the new IIS can host your WCF even if it isn't using tcp. Otherwise you just need to write an application that opens a service host, which you would usually wrap into a windows service. But as #MArk Seemann pointed out, you get lots of freebies by running your service in IIS.
Don't have any experience with the PeerTcpBinding but I can tell you that the NetTcpBinding is nice and fast plus it comes with all sorts of goodies like encryption and authentication if you want it.
I'm developing some kind of server service who gets in action and stop on an specific range of time, I need to write a monitoring app to receive some status text sent from the service in the same local host.
It's the first time I need to comm between processes, I've been looking for some methods, wich do you believe is the best for this case? why? pros and cons for each one?
Remoting
Named pipes
Windows messages
local tcp connection
Database table log (I'm using a database so it's another option)
Datafile on disk
Edit:
I'm using .net 2 so the great wcf solution doesn't work for me :(
See this SO question:
C# IPC Best Practises
You almost certainly want to use WCF. This replaces other .Net technologies such as remoting. Also, if you use WCF:
Other clients could also subscribe to that status information in the future.
The service listening to status updates could be run on another physical box if you needed to scale out.
If you're really just looking for "status messages" - as opposed to an actual client app - then you can use Trace/Debug.Write* statements. DebugView will pick them up if it's running, and can also be used across hosts. And, of course, you can add other listeners via config file if you later wanted to save the messages.