Web Service vs Form posting - web-services

Question

I have 2 websites(www.mysite1.com and myweb2.com, both sites are in ASP.NET with SQL server as backend ) and i want to pass data from one site to another.Now i am confused whether to use a web service or a form posting (from mysite1 to a page in myweb2)
Can any one tell me the Pros and Cons of both ?

Answer 1

By web service I assume you mean SOAP based web service?
Anyway both are equal with few advantages. Posting is more lightweight, while SOAP is standardized (sort of). I would go with more restful approach, because I think SOAP is too much overhead for simple tasks while not giving much of advantage.

Answer 2

Webservices are SOAP messages (the SOAP protocol uses XML to pass messages back and forth), so your server on both ends must understand SOAP and whatever extensions you want to talk about between them, and they probably (but don't have to) be able to grok WMDL files (that "explains" the various services endpoints and remote functionality available). Usually we call this the SOAP / WS-* stack, with emphasis on 'stack' as there's a few bits of software that needs to be available, and the more complex the SOAP calls, the more of this stack needs to be available and maintained.
Using POST, on the other hand, is mostly associated with RESTful behaviours, and as an example of a protocol of such, look to HTTP. Inside the POST you can of course post complex XML, but people tend to use plain POST to simplify the calling, and use HTTP responses as replies. You don't need any extra software, probably, as most if not all webkits has got HTTP support. My own bias leans towards REST, in case you wonder. Through using HATEOAS you can create really good infrastructure for self-aware systems that can modify themselves with load and availability in real-time as opposed to the SOAP way, and this lies at the centre of the argument for it; HTTP was designed for large distributed networks in mind, dealing with performance and stability. SOAP tends to be a one-stop if-it-breaks-you're-stuffed kinda thing. (Again, remeber my bias. I've written about this a lot on my blog, especially the architecture side and the impact of SOA vs. ROA. :)
There's a great debate as to which is "better", to which I can only say "it depends completely on what you want to do, how you prefer to do it, what you need it to do, your environment, your experience, the position of the sun and the moon(s), and the mood my cat is in." Eh, meaning, a lot.
I'm all for a healthy debate about this, but I tend to think that SOAP is a reinvention; SOAP is an envelope with a header and body, and if that sounds familiar, it is exactly how HTML was designed, a fact very few people tend to see. HTTP as just a protocol for shifting stuff around is well understood and extremely well supported, and SOAP uses it to shift their XML envelopes around. Is there a real difference between shifting SOAP and HTML around? Well, yes, the big difference is that SOAP reinvents all the niceties of HTTP (caching, addressability, state, scaling), and then use HTTP only for delivering the message and nothing else and let the stack itself have to deal with those niceities mentioned earlier. So, a lot of the goodness of HTTP is ignored and recreated in another layer (hence, you need a SOAP stack to deal with it), which to me seems wasteful, ignorant and adding complexity.
Next up is what you want to do. For really complex things, there's lots in the webservices stack of standards (I think it's about 1200 pages combined these days) that could help you out, but if your needs are more modest (ie. not that crazy about seriously complex security, for example) a simple POST (or GET) of a request and an envelope back with results might be good enough. Results in HTTP is, as you probably know, HTTP content-type, so lots is already supported but you can create your own, for example application/xml+myformat (or more correctly, application/x-xml+myformat if I remember correctly). Get the request, if it's a response code 200, and parse.
Both will work. One is heavy (WS-* stack) depending on what your needs are, the other is more lightweight and already supported. The rest is glue, as they say.

Answer 3

I would say the webservice is definitely the best choice. A few pro's:
If in the future you need to add another website, your infrastructure (the webservice) is already there
Cross-site form posting might give you problems when using cookies or
might trigger browser privacy restrictions
If you use form posting you have to
write the same code over and over
again, while with using the
webservice you write the code once,
then use it at multiple locations.
Easier to maintain, less code to
write.
Maintainability (this is related to
the above point) ofcourse, all the
code relevant to exchanging data is
all at one location (your webservice)
There's probably even more. Like design time support/code completion.

Answer 4

From my little experience I'd say that you'd be best using a web service since you can see the methods and structure of the service in your code, once you've created it at the recieving end that is.
Also using the form posting methos would eman you have to fake form submissions which isn't as neat as making a web service call.
Your third way would be to get the databases talking, though I'm guessing they're disparate and can't 'see' each other?

Answer 5

I would suggest a web service (or WCF). As Beanie said, with a service you are able to see the methods and types of the service (that you expose), which would make for much easier and cleaner moving of data.

Answer 6

I agree with AlexanderJohannesen that it is debatable whether SOAP webservices or RESTful apis are better, however if both sites are under your control and done with asp.net, definitely go with SOAP webservices. The tools that Visual Studio provides for creating and consuming webservices are just great, it won't take you more than a few minutes to create the link between the two sites.
In the site you want to receive communication create the web service by selecting add item in VS. Select web service and name it appropriately. Then just create a method with the logic you want to implement and add the attribute [WebMethod], eg.
[WebMethod]
public void AddComment(int UserId, string Comment) {
// do stuff
}
Deploy this on your test server, say tst.myweb2.com.
Now on the consuming side (www.myweb1.com), select Add Web Reference, point the url to the address of the webservice we just created, give it a name and click Add refence. You have a proxy class that you can call just like a local class. Easy as pie.