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Get Just the Body of a WCf Message
Good Morning,
I have a WCF service that build a complex object then sends it to the consuming client. Currently the service works great but the xml is reinflated / deserialized on the client and I don't want this as the client wants to work with the XML.
So is there a way to get the "XML document" that is transmitted as a part of the WCF service response. Of course I could just serialize it again on the client but really why do extra steps if they can be avoided.
TIA
JB
Although there are possiblities to hook into the multiple WCF receive/send steps on both server and client sides, where you could influence on how the serialization is executed (not not executed in your case), I believe that would be too much overhead for your scenario.
You'd be better of to simplify the workflow and stick with the out-of-the-box functionalities.
I think the easiest approach would be to manually serialize your objects only on the server side and simply send the result as a string back to the client.
To remain flexibility (you might later want to add more data accompanying the serialized data) put this serialized XML into a property of dedicated Data Transfer Object (DTO).
This DTO is then send to the client who simply reads the XML from that property.
Under the hood there still is, of course, some serialisation going on. But this would be the built-in functionality hat is totally transparently executed by the WCF service/ client communication. If you do not have a serious reason to do influence it manually, leave it as it is. If you do not know what you are doing you might instead open the box of Pandora...
Sending a simple object like the above described DTO should not be much of a deal here. I mean, this scenario would mainly be sending a bunch of strings over the wire, which should not cause any troubles and very little overhead.
Related
First off a little context, I work for a channel manager company that builds custom endpoints for their clients to talk to. We currently mostly code in c#.
This is the first time we are connecting with a client that asked us to support a soap web service.
Sadly, we don't have previous experience in this and I can't find any concrete explanations to what it looks like to support a SOAP call.
Currently, it looks like that I have to simply use text processing methods to run through the received XML and parse it in a non-generic way.
But this feels like there should be a more straightforward approach since the protocol is almost 20 years old.
For almost every search result I only get examples of what the XML looks like, but what I'm interested in, is what I need to implement in my application to host an endpoint for the client to successfully post and receive a SOAP message from. And if there is a way to do this without something like XmlWriters/Readers.
Anything to help me get on my way mary is appreciated!
Greetings, Davey
WCF is the least outdated library for offering SOAP.
When you can define the contracts then you're in luck, that's just writing a C# interface.
But when necessary you can also import WSDL specifications and generate C# from that.
it looks like that I have to simply use text processing methods to run through the received XML and parse it
Don't even consider that. Everything is under control of schemas. And you will also have to generate valid return packages.
I am thinking of making a server/client application that does this: the client(s) will connect to the server and the server will send back a list of folders (probably music or videos) that the client will be able to stream or download. I am going to make a GUI for this so that it won't be a text-only interface. I want it so that when the client connects to the server and gets the information about the media files that can be streamed/downloaded, the client will show the folders/files in an explorer-like interface (folders will show up with a folder icon, videos will show up with a video icon, etc.)
This seems really big to me but I really want to learn more about socket programming with C# and feel that getting my hands really dirty is the best way. As you can imagine, I have a lot of confusion about how to start this and what it is that I need to do to make this work.
The first part of my question is: If I want to let a client receive a list of files/folders and also have the ability to download/stream them, do I need to do something with transferring binary data using sockets or am I completely wrong on that? If I'm wrong, do I need to use something else like file readers and somehow use them over sockets?
The second part to my question is: when I transfer this information over to a client, how can I make the client show the appropriate icons for videos, folders, mp3s, etc.? I'm thinking that if I have to transfer binary data I will have to use that data to somehow populate the client GUI with the correct icons/data. I am stuck on exactly how to handle that. Are there certain methods/classes that I can use to parse that data and do what I want to do with it? Again, I don't know if I'm wrong about needing to transfer binary data but either way I am confused on what it is that's necessary to handle this.
I apologize if any of my terminology is wrong. I am obviously not an expert in C# yet ;)
Any time you are sending data between machines (or between processes), you are already talking binary data (you could argue that everything is binary data, but when working with it as an OO model it doesn't feel like it). The point here is that all you need to do is serialize your messages. There are a myriad of serialization frameworks - some aimed at convenience, some aimed to range-of-features, and som can use aimed at performance (minimum bandwidth etc).
Even the inbuilt ones would work - for example, you can use XmlSerializer etc to write to a Stream (such as the NetworkStream you typically use with a socket). But please - not BinaryFormatter (it will hurt you, honest). Personally I'd use something a bit less verbose such as protobuf-net, but I'm somewhat biased since I wrote it ;p
However, note that when working with sockets, you are typically sending multiple (separate) messages as part of the conversation. In order for each end to correctly and conveniently read the right data per-message from the stream, it is common to prefix each message with the length (number of bytes) - for example, as a little-endian int taking a fixed 4 bytes. So the reading process is:
read 4 bytes
interpret that as an int, let's say n
read n bytes
run that data through your deserializer, perhaps via MemoryStream
process the message
and the sending process might be:
serialize the message, perhaps to a MemoryStream
query the length and form the 4 byte prefix
write the prefix
write the data
You don't have to go to as low level as Socket, unless you just want to learn of course.
I suggest using WCF. It will completely meet your requirements, will be flexible and you will not have to deal with sockets directly.
WCF is a big framework, but you can quickly learn how to use it.
Introduction to WCF
Here you can find how to retrieve and show file icon in Windows.
If you client is hosted by Windows, you don't need to transfer icons, you can just retrieve image on the client by filename/extension.
I've been doing some reading up on XML serialization, and from what I understand, It is a way to take an object and persist the state in a file. As for the implementation, it looks straight forward enough, and there seems to be a load of resources for applying it. When should XML serialization be used? What are the benefits? What are situations that are best helped by using this?
The .NET XmlSerializer class isn't the only way to persist an object to XML. The newer DataContractSerializer is faster, and also allows an object to be persisted to a binary form of XML, which is more compact.
The XmlSerializer is only getting limited bug fixes these days, in part because so much code depends on the precise details of how it works, in part because it is associated with ASMX web services, which Microsoft considers to be a "legacy technology".
This is not the case with the DataContractSerializer, which continues to be a vibrant and important part of WCF.
You've answered a little bit of the question in your post. It's great for persisting the state of an object. I've used it in applications for saving user settings. It's also a great way to send data to other systems, since it is standardized. An important thing to remember is that it is easily human readable. This can either be a good or bad thing depending on your situation. You might want to consider encrypting it, or using encrypted binary serialization if you don't want someone else to be able to understand it.
EDIT:
Another gotchya worth mentioning is that the .NET implemented XMLSerializer only serializes public members in a object. If you need to persist private or protected members, you will either need to use a customized serializer or use another form of serialization.
Its good for communication between disparate systems. E.G. take a Java app and a C# app and allow them to communicate via a webservice with serializeable XML objects. Both apps understand XML and are shielded from the details of the other language. And yes while you could fire strings back and forth, XML gives us strong typing and schema validation.
this is just from personal experiences - XML serialization is good for web services.
Also, if you want to modify (or allow the modification of) the object/file that you're storing to without using the application that you're writing (i.e third party app), XML can be a good choice.
I send an array of Objects of type class I wrote, using HttpWebRequest, so I cant send it as an object , because im mixing HttpWebRequest + Soap (that Im writing), and in Soap you cant send a non predefined Objects as String, int , ... .
so I used XML serialization to convert my object to an XML string and send it through my HttpWebRequest .
I have built two programs in C# and I am sending simple strings through the sockets. This is fine for the moment but in the near future I will need to send more complicated items, such as objects down the sockets and eventually files.
What steps would I take to do this? What purpose do the buffers serve for the sockets/streams? Apologies if I am a little vague.
If you are sending objects, you have to really be careful with what you do and how you are planning on using those objects on the other end. All properties need to be serialized. If you are going to have large amounts of data in theses objects, you may want to use binary serialization instead.
Also, look at the guidelines posted here: MSDN Serialization Guidelines
If you are going to be sending objects, you may want to look at either .Net Remoting options or WCF Services if applicable. Rolling your own socket handlers and then using it for complex operations is asking for a lot of time and pain, especially if you haven't done it before.
There are many options, but basically you want to serialise the data into a format that will go through the socket.
Worth looking here into xml serialisation.
One way you can handle this is to serialize your object into XML, send over the socket, then deserialize it. I've done it this way before. However, I (being fairly new to .NET) just learned about the JavaScriptSerializer, which I believe makes this process a lot easier for you.
You need to serialize the objects.. Mark it with [Serializable] attribute and use some serializers.. Example can be found here.
First thing in any comms situation is to consider that anything you send must be able to get serialised and de serialised so that it can get over a comms channel. Next you must consider that comms have latency (its not instantaneous), and then the fact that it can fail.
After this you consider the protocols and technology to enable the above to be factored in.
I'm hoping someone can advise me on how to solve my networking scenario. Both the client and server are to be C# / .NET based.
I basically want to invoke some kind of web service from my client in order to retrieve both binary data (e.g. files) and serialised objects and lists of objects (e.g. database query results).
At the moment, I'm using ASPX pages, using the query string to provide parameters and I get back either the binary data, or the binary data of the serialised messages. This affords me a lot of flexbility, and I can choose how to transmit the data, perform simulatanous requests, cancel ongoing requests, etc. Since I can control the serialised format, I can also deserialise lists of objects as they are received which is crucial.
My problem isn't a problem as such, but this feels a little hack-ish and I can't help but wonder if there are better ways to go about it. I'm considering moving on to WCF or perhaps another technology to see if it helps. However, I need to know if it helps with my scenarios above that is;
Can a WCF method return a list of objects, and can the client receive the items of this list as they arrive as opposed to getting the entire list on completion (i.e. streaming). Does anyone know of any examples of this?
Am I likely to get any performance benefits from this? I don't know how well ASPX pages are tuned for this, as it surely isn't their primary purpose.
Are there any other approaches I should consider?
Thanks for your time spent reading this. I hope you can help.
WCF does not natively support streamed collections. (Which are not the same as Streaming Message Transfer)
However, see this blog post.
I recommend that you use ASHX files (Generic Handlers) instead of ASPX pages (Web Forms), as they have far less overhead.