As Angular is a web based technology, I'm not sure why you thought it appropriate to post here in the .NET forum. Saying that, if you want to learn Angular.js, then I would heartily recommend that you take out a Pluralsight[^] subscription. They have excellent videos that will help you learn.
This isn't as easy as you'd expect it to be. At first, you might be tempted to go with a regular expression, breaking each line on .!? but this won't really work because it's common to have sentences that include abbreviations, which end in the period. So, you're going to want to look at using a Natural Language Processor (NLP) to accomplish this. Now, this is a large area and isn't one that you can really answer in a forum. I'm afraid, if you have a requirement to do this, then you're going to have to research which NLP will best fit you.
I have a asmx-webservice. When I try to access it by using the URL directly, I get an error "Requested Format Unrecognized" (I hope the translation is correct; I have a Dutch version). When I try to make a service reference, I get the following error: There was an error downloading 'http://bliep.hulppeldepup.nl/bliep.asmx/_vti_bin/ListData.svc/$metadata'.
The request failed with HTTP status 405: Method Not Allowed.
After some googling, I got to this page https://support.microsoft.com/en-us/kb/330221/nl that tells me that I have to adjust settingsin the firewall to remove unknown headers. Unfortunately it doesn't tell me how, and I can't find the answer anywhere.
The strange thing is, that on the same site I have another asmx webservice that I access through AJAX, without problems. Now I want to do the same thing with a Windows Forms application, and problems arrise.
How can I make my asmx webservice available for my program?
Yeah, but it's a Web Service that runs on top of the ASP.NET framework. The .NET Framework is much lower in the stack and your question is about functionality at the ASP.NET level, not the .NET Framework.
The answer to this is, try them out. Measure their performance for the use cases you have in mind. Your question is far too simplistic to make a reasonable judgement because performance could vary wildly for different use cases. Apart from anything else, you'll need to take into account features such as scaling out the application, how load balancing affects your app, does different parts introduce bottlenecks, as well as defining what acceptable performance is.
In addition to what Ryan said. Web services are generally used to have a multi-tier architecture where web services work typically on the middle tier.
Consider a scenario, where we have a database and a website that fetches data from this database.
Now, you have a requirement that you need a mobile app, that will use data from the same database.
DB---> Mobile Application
You will be re-writing the entire logic to fetch data from DB in your mobile app
To save yourself from such problems. Multi-tier architecture is the solution
DB--->Web Service--->Mobile App
DB--->Web Service--->any other client who can consume your web service
By using this strategy you just have to write you Data Access Layer in web service only. Your clients will have to consume this service and get he data from it.
There are a lot of scenarios where web services help a lot, integrating disparate systems using web services is another example. Google the use of web services and I am sure you will get a lot of stuff related to it.