AngleSharp NET Headless Browsing

hi there we go there's our camera and can you share your screen sure let's see so good is he an angle sharp yeah yeah so Florian we've we've talked over over the years here you're when angle sharp joins on that foundation big fan thanks Shirley I'm quite happy to share now what angle shop is about I mean for me it's anyway like Christmas two best events of the year coming together dotnet Kampf happening globally and the Oktoberfest is just around the corner here the stage is yours Thanks so without further ado I will just jump into topic and hopefully and make it in time the topic is angle sharp which aims to be a dotnet headless browser let's see where we are and before I jump into it fully in the water a few words about myself Microsoft MVP for developer technologies I'm also a contributor to open source projects mostly Anka top of course and I'm very enthusiastic about writing some articles of technical nature and speaking at events if the time allows it always be happy to be invited and appreciate that professionally I'm a solution architect at a small start-up called SMAP yacht and they are specialized in distributed web applications and the web is also the topic of this session one word of remark since this is an online session I cannot see all your faces so excuse me for being either too fast or too slow I hope that the recording will then at least a little bit well give you a payback on this one otherwise you can always reach me on github or on Twitter if you have a specific question now yeah yeah thanks thanks alright now what is on our plate today we will first start by a quick introduction what is Engel shop why could it be helpful for you since angle shop is an HTML app browser we will also need to have a small excursion html5 we will do that by example I selected three examples that should be Lestrade why HTML parsing is not so simple as just putting out a regular expression then we will go into topic of extensions this is one of the things that makes English up special and we try to to always improve our reach and what we can do with it and finally a small outlook what the future of bangle shop will bring so what is angle shop has already told you it's a library for parsing HTML but it's in fact a little bit more than that what we try to do in order to pass HTML 5 correctly I mean there's the core specification but there are all kinds of specifications actually and if you want to really get across on what's on the web you should not consider just one specification but all the side specifications also play a very important role like for instance this one little thing called JavaScript right I mean many websites are unfortunately these days only accessible if you also have a JavaScript engine running or part of the information may only be displayed in conjunction with special CSS rules or may make only sense which diseases Luis so there are all these different technologies that come together and form what we call the web today and if we really want to get access to that information we need also a browser engine that's capable of doing that of course your stand-up browser can do it but can you do it in god net without any let's say RPC calls or whatever and that's the mission of English shop now what we can do is we have a full stream processing unit like a standard web browser does which means we do not stop when whites arrive we always evaluate them we don't wait until all the content was received we do it on the fly we have a collection of web utilities for that most notably in the encoding space but also for instance we have our own URL parser that's just because the URI type that's Internet unfortunately it's not capable of well parsing all the available URLs that are out there this URL parsing that we included follows the specification by the heart and therefore can handle all the cases what else we can do besides HTML CSS already remarked that Java Script plays an important role yes we have a solution for that unfortunately at the moment it can only deal with simple JavaScript and the vision is of course to improve the reach here and this is where customizations and extensions come in because at the end of the day we don't want to create as one giant monolithic library we want actually to foster a whole ecosystem of plugins where everyone can say oh this is one of the things angle shop cannot do or does not do well at the moment but I can just customize this and come up with my own plug-in now looking at the history of the project it always started I think round in 2012 it was actually after an MVP summit I was on the plane and I saw yeah that's that's right an html5 pause I mean what else could be could be done on a plane honestly it was a different angle so to speak back in the day on the project but I realized an html5 parser is one of the things that's missing in the.net ecosystem you have another HTML parsers right but none of them have been following the html5 specification by the heart at this point in time in 2013 I put it out of github and initial reaction was quite good I was really surprised so there seem to be some kind of a demand and so I kept on going and in 2015 grid and important milestone with integrated extensibility we demonstrated that scripting engine can be brought in which was quite cool because suddenly you had not only just a static document object model a static representation of the page you're the linguist but actually it could be made alive what JavaScript brings for instance to the table and then from that point on just a lot of bug fixes a lot of improvements and a major refactoring of the API to the end user also happen and the milestone here is the version 0 10 so right now we are at 0 13 and we want to hit the 1 0 milestone all the major breaking changes that happen since 0 10 all quite minor but still breaking in one or the other area now from 0 9 - 2 0 10 that was a huge change so there we really made a drastic direction change but I think it was for the better and the ecosystem also lives now on top of the 0 10 version and of course the successes now one short claims that what how parsing HTML looks like it's like any kind of parsing so if we could draw pretty much the same picture for let's say even programming languages like C sharp they of course may have what this thing called a back end with optimizations etc and coding machine happening that's not the case here but nevertheless the parsing stages alone the front end is pretty much the same so we start with a stream a stream of just bytes and they are interpreted in a special way by a preprocessor that also does some sanitization in the end the goal of this pre-processors actually to get us characters that we can work with then a tokenizer comes into play no the tokenizer takes a bunch of characters as oh now that's a valid token for instance an opening tag or a closing tag or an attribute or text or a comment all these kinds of different building blocks that we have now until this point we are still in the linear phase where we say okay we started with a linear stream of bytes we have done a linear stream of characters and now we have a linear stream of tokens now where does the tree the document object model come from well that's done by the tree constructor so that is fed on the tokens coming from the tokenizer and now here is the semantic information it says okay I've seen that opening tag I can now close it that's valid or here there is no content allowed I will just place it on the sibling element so all these things happening in the tree constructor and then we have a dynamic object model which is called the Dom so at the end of the day this is all what what's included in English after then need to do anything you just for instance present the stream to English art and English afters all the rest at the end you get an eye doc you meant for instance instance and with this instance you can actually play around you can serialize it back that's what we will see you can append new elements or get further information out of it so let's just look at some examples learning a little bit what makes html5 so so complicated first very simple piece of HTML code what do you should recognize here is I left out some of the let's say standard elements like we don't see an HTML tag here we don't see head we also don't see body well that's not an error that's actually a valid html5 document and there are big sides for instance the Google arrow page out there which use exactly these rules to save a few bytes here and there so what invalid HTML 5 part should do it should insert these things for us so it should automatically insert for us an HTML opening tag it should insert for us and head opening tech it should also close the head and it should also when the magenta coat is reached create a body element for us all these things should just happen automatically that's by the specification anguish of does that we will see that in a second now a second example where it gets a little bit tricky is there are some special kind of stopping rules in HTML for instance there could be in a unsorted list and entered a space of a list item now if we are in a list item we can just write another list item with the first one or the formal one being implicitly closed so that's all by the specification simple possum may not like this because here the pre constructor needs to have all the additional logic as an example if we look at raiser for writing fuse in asp.net core MVC we will recognize that we need to close the list item now that may have been a good design choice for performance reasons but on the other hand of course it limits the output that can be generated because you can never output an HTML like this using razor unfortunately now the same rule that applies to list item can also apply for instance a paragraph there are multiple of these cases again this these are not arrows these are not even warnings this is just well it HTML and the automatic closing just happens for you a third example I want to give is in a table space well tables are one of the most complicated parts of the html5 specification because there's so much that could go wrong and every edge cases essentially handled there's another space which has to do with formatting elements but since formatting elements are more or less a legacy thing especially with the edge cases described in there I will just focus on table with the simple example now what a protein here is there have been some elements inserted magenta ones so we've break row here and we have an iframe there just inside the table note also there is no tea body element for instance which is also something that needs to be inserted automatically by the html5 parser in addition to these let's say misplaced elements we also have an invalid closing tag so it's not even an invalid Tec I mean web components or angular or any any kind of spar framework these days uses custom tag so that's that's that's no problem and then we have also in green the table row which is just that's saying often here it needs to be placed in the table itself and it isn't so what should we do is death so let's have a look and all these three cases in the demonstrate demonstration of angle shop all the demos you'll see today available on github the URL is on the screen right so for the first demo we'll just briefly explain what the angle Sharpe are does what we do here is we create a new so-called browsing context browsing context you can think of as a like a tap in your standard browser so that's one instance where now a page can live what makes a browsing context special is that you can configure it you can tell it what it can do and what it cannot do like when you say in your browser to your current app well you are not allowed to run JavaScript you can do that here too so we can do browsing context we don't specify any configuration which means it's the default one and then we open a new page as the stream may be well evaluated asynchronously we need to do that in an async method but luckily c-sharp a discovered here what we use for simplicity is not now some remote remote source we use actually the small snippet that's on top of here so we just apply the content via what is called in English up a virtual response so we say oh so you don't have an address where your page lives you don't even have anything like that so you can just construct how the response to our request would look like and we say yeah our response has the following content it's this source and it also comes from a certain address so the address is completely optional I just included it here because we will see it in the document object model appearing as the base URI and base URIs are very important because they give relative URLs well the base that's required for resolving them all right mmm so when we do that we end up with this i document instance and what we can now do is to illustrate that angle shop did everything right we sterilize it back to an HTML string again using the to HTML method so if I use this and run the code you see the output it's pretty much the same document that I inserted except will suddenly get the HTML we get the head we also close the head we open the body and at the end of our whole HTML document we also close everything that was still open but that's all done by angle shop now the second example we had we use the same code just a different HTML snippet we should see that the list items will be closed before we open a new one or before we close obviously the unsorted list and the same applies here with the paragraph we also need to close them properly so let's just run it and we see same action else on example one except now of course in addition we see all the stopping correctly evaluating so far so good let's also have a look at the third one and here let's also debug what actually the document looks like so before we write it to the console let's just see what's in there could be a little bit too small so I will just make it a little bit larger I hope Skype plays with me here so what we do is we have all these capabilities that if you are familiar with the document object model API from JavaScript will look very familiar right so for instance we have an old property and that will contain all the elements in here we can also iterate over them there could be a cookie for instance or we see of course our base URI that was successfully applied so all these things are there and it's it's a full document object model just done in c-sharp without any remote procedure calls to to chrome or any other evergreen browser happening now regarding the output that's what we expected so the the table Road it was outside of the table that was completely omitted otherwise we see the standard construction happening the break row and the iframe have been put in front of the table and we see the insertion of the tea body happening so all done for us by English shop it would have been done of course by Chrome or Firefox or any other evergreen browser out there too so this is a specification dictates okay now let's talk about extensions for a moment so what you saw is what the core of any shop can can do for you in a nutshell so it really makes sure that whatever the HTML looks like on the page is interpreted 100% as a real browser would do right and that's of course important because you don't want to end up with something that's well not what you would expect from just for instance packing it in in Chrome now the English up core doesn't deal with JavaScript English of course doesn't deal with with CSS but they are luckily these plugins and how the ecosystem looks like is we have this base layer of English up core providing the common utilities and then we place on top of it useful libraries like for instance English up CSS which deals with the CSS object model and we try also here to be fully w3c conform which means whenever they came up with suspect how an API should look like we follow that spec so it's not only about behavior it's also about what the API looks like and that should give you some kind of a learning improvement because if you know it already from JavaScript you can apply it directly in in angle shop if you know it from English shop and someone asked related to do it in JavaScript well you can also apply the knowledge there and this too in one say in my opinion as always it's great to have we also have English a file which will demo in a second this brings additional io capabilities like requesters or cookie providers and then we have libraries that are either an experimental stage like English up jeaious is one of these or which are just planned like English a media could be one of these things that would also support certain kind of streaming capabilities and could also be quite cool if you say oh I got this site and there is a video stream on it I can log in and then suddenly I can bring this video stream to I don't know WPF that would be quite quite awesome but we are not there yet but that's part of the vision all right so let's have a look at persistent cookies using anger shop io so a little bit of background to this demo I got a web server running locally a really simple one the page which needs a locking mechanism to display a secret now all the locking mechanisms in the web pretty much work these days video is of course some api's but then we are anywhere in the safe side if you have a che WT or anything like that or we have a cookie based authentication that's for most of the sites that are relevant for angle shop the case so when we have this cookie problem we potentially need a cookie solution right out of the box angle shop already brings a cookie provider but that's based on the cookie container of thought net that has several disadvantages most notably it doesn't work with all the cookies out there on the web it may crash it may complain you know this stateful model do not recognize so what we did in one of the extension library is called angle shop IO we created a cookie provider following the official specification and we even went further what we have in there are two ways of using it one way is in memory where you say okay when the application closes cookies are lost it's good and the other way say oh you can persist it or however you want to by default on the local file system and that's what it should show so we use a custom configuration now that's done like this you have the configuration class and we just say we will start with the default one and then we add additional capabilities so what we do is we add the persistent cookie capability and we say oh yeah you need to store it somewhere the sync file path is in My Documents to file demo cookie we also add additional requesters like an HTTP request that's based on the HTTP client that's just more modern and the one that comes with anguish up out of the box and then we say yeah English are you allowed to actually make requests to the network so is a with default loader now when we run this thing what will happen is we just switch to authentication we will have different kinds of stages oh sorry I'm still need to remove this little file so let's run it again sorry for that if different kinds of stages so we start not being locked in so the page looks like this you need to login for obtaining the secret luckily we have to log in link here so we navigate there then this page contains a form we fill out the form with the user and the password press login it's all done and then we automatically redirect it and here we see the secret so obviously proves Wayne is Batman what but yeah so that's just how the word works and this was the the angle shop order the code that we used in C shop using angle shop say okay we can use a query selector if it's there we navigate to it then we submit the form and then we're locked in now if I run it again this cookie file is created has been graded and so we are already locked in so we see it the secret directly I'm Batman parade and the reason how it works is because sorry it's because yeah we have this file that follows the old Netscape cookie file specification and that actually includes all these different cookies that have been used now for the localhost domain and we just transported over alright so going into the final stages I also want to show you JavaScript before wrapping up now JavaScript all said is also just a library in an experimental stage we only need to use with chess and then we can apply some simple JavaScript let's just make the demo before we run out of time [Music] pretty much the same thing now what we will change is the document title because that's right now sample and it will be changed to simple manipulation what we will also do Israel right out this special kind of a spawn element so let's just run it and what we can see is the title changed now in the serialization it's now simple manipulation and we got this spawn break so this simple JavaScript pose applied correctly evaluated correctly again angle job chase is experimental and you will not be able to run let's say large-scale single page applications with it at the moment okay so next steps obviously is shipping one zero is very important improving huge is super important and then refining things of the ecosystem like angle shop CSS or bringing up new additional libraries like one is for instance saying especially with Swiss blaze around the block that could be really interesting English of media is said but also things like English of renderer could be quite interesting especially if you want to say everything is just managed code I don't need a web browser for displaying HTML which could open a lot of interesting use cases in my opinion we are always looking for contributors would be much appreciate if you have a look any kind of contribution maybe finding a bug fixing something on the documentation or also discussing how the API improved would be superb I appreciate all your time you'll find more information about the project at English architect at i/o and you can always give me a tweet or reach us via via for instance I'll get that chat thanks a lot alright Florian that was a great much yeah that was great I've I tried parsing HTML with some regular expressions back and it's a badness it's just math it's it works for the simple ones though but once you don't know what you are receiving you're just out of luck I guess it's got so many quirks as you showed and and we're thankful that you're doing the hard work so we don't have to appreciate it appreciate it all right well thanks so much Florent you have a good day and enjoy Oktoberfest enjoy to a base take care they can't buy

.NET Standard Revisited

I think there's still some confusion around dotnet standard particularly around why it was invented and how it affects the apps you're currently building on this episode of visual studio toolbox Kathleen dollars gonna do her best to clear up that confusion hi welcome Visual Studio toolbox I'm your host Robert green and joining you today is Kathleen dollar hey Kathleen hi how are you doing great we've talked quite a bit about dotnet standard we being Microsoft emo has done several videos on channel 9 it was featured at connect you talked about into conferences and yet I think there's still some confusion about it and yet and yet so what we had to do in today's show is clear up some of the confusion not so much about how it works because I think that's been covered very well but more about the why it was invented why and when people should care so you know just for example if I'm maintaining existing wind forms of WPF apps do I need to care about this well to start with if all of your code is in your wind forms up and your WPF app you can't use dotnet standard it's really not in the picture but on your wind forms app or your WPF app you might have some of your code in the wind form and WPF application itself in that in that entry level in that entry point and then you might also have some class libraries that you're using that I've already written you've already written or now I inspire you to split them out and put them into something but you've got now this class library you can take the class library and have it target dotnet standard and that's what that's what you can do and we could talk more about why you want to do that right so do you want to go there now or do you want to talk about all the other ways you might wind up caring about dotnet standards another example okay so I do a bunch of xamarin and I do file new project there's always been two buttons shared project and the other button which used to say portable class library right and magically it said dotnet standard library I always choose that one because it's not the shared project right then I do the exact same things I write the Aksum co2 put the code and the sam'l in the exact same place and when I build the application I understand its using.net standard instead of a part of a class library but I haven't done anything different so so in that case that's great behind the scenes you are using dotnet standard instead of a PCL and there are some key differences between the two so let's start off with why that happened why portable class libraries alright anybody checked when we did a an episode on it a couple of years ago they were awesome so I'm ceremoniously dunk yeah how did they do they were actually pretty cool so they were great it's just that dhania standard he's that much greener in that much cooler so let's talk about the difference so portable class libraries walked into a world where there were a lot of frameworks and across all these different frameworks there were different rules that API was just a little bit different okay so what a PCL does it says those things you have in common you can use right if it's not in common between these two things you can't use it and if you add a new target you're going to change what you can do so you could have like dotnet you would use PCL and it could be like xamarin and something else and you're out there in the field and everybody's happy and all of a sudden somebody says let's target Silverlight and then as you add that other requirement in you lose a bunch of api's and you can actually break yourself in the field so because PCM was always an afterthought they don't fit into today's world as well as we want them to so everybody took a step back and they said well instead let's create the standard ahead of time that html5 is a standard okay that's what a standard is it's basically a word document somewhere so there's a dozen standard people got together and said this is the things we can agree on and there was a lot of work to actually get the right set of features in that now if any platform any framework is going to say I support dotnet standard they have to follow those rules so instead of being an intersection of what was already written it's a standard that then gets pushed out and people have to adopt now that doesn't mean that dotnet saiful framework or xamarin has to make internal changes because it doesn't matter how they implement this it can be any way in the world a lot of the zamarons stuff actually pretty well aligned and so it can just call straight in and it's just fine for the rest of the stuff there needs to be for like dotnet framework there needs to be a redirect so it says oh you said you want to call this but I know what you really mean is this API that's just a little bit different and will just redirect you over there weird weird surprise Robert me on that one okay I'm I write some code hmm targeting what I think is the dotnet framework but I'm not okay I just said if you're targeting dotnet standard you're actually targeting dotnet standard it's what we call a reference DLL and let me show you real quick what that looks like so if I come over here and I go to the dotnet standard this is actually github dot net standard pick one which one do you want to pick just am not data will do data okay so I'm just going to open that just open it no right-click just open it come on okay so in this opens you're going to see the actual coded on it standard so it's a standard it's a document it's a document written in code okay you're with me yep all right so this is what actually looks like and it has enums because of course we need those to define the API surface level okay but it also has a class now there's something kind of unusual about that class it doesn't do anything right it's either empty or it throws okay that's it so a reference library is a library that's empty so this works just fine you can target this and Visual Studio or your bill system or anything that needs to understand your libraries can look at this and go hey I get it okay because they don't care that nothing actually happens and then when you go to run on your full framework machine then it's this is called net standard DLL that's what this builds so when you that's on your your box where you're doing your build and then you go to production and you go over and whether it's a Linux box or a Mac box or a Windows box goes there and it says well there's an standard DLL associated with the framework I'm running now use that and at standard DLL which doesn't have empty places okay instead of the one that you compiled against so inside of those brackets it may say oh don't do this do that okay so the brackets here may call a different API or an API that's just in a different spot and all of that gets worked out however the that framework wants to do it the only requirement is that there be a net standard DLL specific to that framework so that when you write your app and you target net standard DLL and you target this empty reference library it can get thrown out and a real one that actually works can be put in place now the purpose of this document here is to set the rules on what you can call just like a portable class library said you are allowed to call this subset and if yes if you try to write something that isn't supported you'll get a compiler error because it doesn't exist this is now a better more flexible way of accomplishing that right yes compile time if I call something that isn't in thought Nets standard and I've said I'm targeting dotnet standard right then I'll be alerted that I'm calling code did doesn't essentially doesn't exist in case he calls that's correct yes so all of that works very similarly and the difference is that with PCL there was no way to change the API surface if it was just a little bit different it did the same thing but it was just a tiny bit different kind there wasn't a way to really resolve that in a PCO world now we resolve it because on the machine that's actually running we're house actually executing it's not empty there's something in there and whatever that thing is it might just do the job if it's simple it might ask something else to do it it might do a there's even some binding redirects and things that can be involved and so all of that stuff happens behind the scenes that's part of what Iman talks about if folks want to see that on the in his videos because he wrote this stuff he really understands that deep level what what I want us to talk about is why people care and what's the when we step back was the impact this on individual developers going forward so just like with portable class libraries the main impact is one of the main impact servers that the main impact comes if you're writing code it's going to run on multiple platforms it is a main impact that the main impact it's not the only impact but it is the main impact and the other impact comes from the fact that this is also a statement of what Microsoft has determined is the commonality across platforms so another way we can say that is this is the definition of the future for the non what I'm calling an entry level but the non UI pieces so for everything else including some things around console apps for all of these things this is what's defined as where we're going in the future and so even if you're not actually going to run on a different platform if you go ahead and target dotnet standard then you're able to say hey I know I'm within the bounds of what the future is likely to look like and if it's something that's outside of that then I can look for some help for how I get that job done okay because it doesn't its standard 2.0 and there's been a couple of iterations of it was not randomly created a lot of code was evaluated in order to see what do people actually do and it covers the vast majority of what people actually do so if you're writing an application and you say oh I want to do this thing let me see if it's in dotnet standard let me see what to do a little different for it to work another standard and this also supports some of the deprecated and out-of-date ways of doing things so when we look at areas like XML and areas like that we've had a few iterations of how to approach those and this lets you say hey this is the one that I expect to use going forward so where there's something missing there's often a replacement that is a better way going forward okay so I'm working on an existing WPF ever I'm creating a brand new WPF F and I want to build a class library uh-huh I can just build the class library the way I always do not worry about dotnet standard I have access to the full framework from within WPF and I can go and do that and if yes ciello is only ever going to be called from that WPF app then I can just happily do that and not have not need to think about that NIST standard and if I don't think about it I haven't lost anything and the only thing I'm in a challenge on that is I'm gonna say that it's very hard for you to say never ever anybody else will ever want my class library it's easy to say Robert but let's look at the world around us and how much change we've seen and your class library is important in your class library you want it to last for five or ten or fifteen years so if you want to write it with that kind of thinking and you say well I'd like to still be on WPF in 10 or 15 years and have that still be cool but I don't really know what's going to happen there I do know that the core way that we write applications has been pretty static now for a really really long time and Microsoft has found a way to move forward across a lot of technology change using pretty much the same code and the API is is now this is an API level conversation and this is a way to say the api's are going to have a pretty long life not that they'll never change it's just as skin as it's going to change in a very slow level so you do the best job you can to say that my WPF app that work in the background this business logic that extra work that's going on I'm going to future proof that by having it understand dotnet standard now you don't actually have to target dotnet standard you can you can do this a different slightly different way if you'd like you want me to show you how you can yeah okay I can about that in a second so I decide okay future proofing is probably good right so I'm going to target that nest in and I'll create the closet a heat class library targeting a standard so finally project on its standard library I assume right exactly and I target the latest version of the dotnet standard source depending on what version of Visual Studio I'm in right because each version targeted a different version of the dotnet framework but the dot knits how do I know that dotnet standard to supports all of the things that I would have done in my app if I was directly going against the framework am I going to are there things not available to me and is there a way to know that ahead of a time there is more than one way to know that ahead of time so I'm going to open a new browser window here and I'm going to type api's api's of dotnet mm-hmm I'm going to go there and what is your favorite what is your favorite class or method in in side of net so it's gotta be something in system dot data you like system data I do that let's get a little more so let's go to link link yeah okay and let's go to I don't know pick one of those okay we'll just pick anything we'll just pick a refresh mode refreshment table payment no table no idea what we're gonna get here so let's just pick that come on we can do this okay so what we've got done is we've gone to a evaluation of the API itself the API surface layer itself and so we can see the what this class is when you find out some things about it we can find out how many people use it okay so 0.3% of users in one of the ways that this gets evaluated so this information was used in order to build the surface area of the of the.net standard okay and so they also make it available because Microsoft has a at least the dotnet core we share our sin of apps points very high that does not very high this is does not get used very often well this is system data dot link and that's not a real common thing okay we can see where it is it's in.net full framework yeah 3.5 and for coming forward all the way it's in mono and it's in Windows Phone Silverlight okay okay now I'm going to pick one my turn so I'm gonna look for system system dot string and I bet yours mine is more but this is you know this is rig this is a rig a mobile four okay okay so we can find out some things about the system that string class and we can look at its usage and I just wonder about the 15 or so percent that don't use a string but most things use a string most applications use a straining not surprisingly now let's find out some more things about it it's in.net core remember yours was not in net core so now I can see so when I know the actual the actual thing I'm looking for I can find out where it's used okay okay this is one of the things you might want to do more commonly I think what you're going to want to do is look at your code to see hey well this past muster will that can this be a dotnet standard applicants to be a dotnet standard class library what am i what am i using and how would that go and there's something called the dotnet portability analyzer which you can get off of I click this so you can see it go it's in the gallery Visual Studio Gallery or marketplace I guess we call it marketplace now and I have that open I have just a little silly little sample this is just a one of the links samples and I just grabbed one randomly so we could see what's going to happen when we run this so because I have installed that tool it's a physics it's a normal installation because it's installed when I go to the solution Explorer and I right-click I have an option to analyze okay I also have an option to set settings so let's do that first because it helps show what's gonna happen here so this is a kind of an ugly dialogue but you can see what it does you get to pick what it analyzes look at all your choices Wow okay so if you want to know if something will run on Windows Phone Silverlight 7 you can find out ok okay so let's come up and look at the ones we care about which is dotnet core and I've got dotnet core 2.0 clicked I think I'll also do dotnet standard 1.4 1.5 1.6 and to those seems like some pretty good so pretty good pretty good ones okay unless there's something you see there you just really want me to close mine okay so because I've got that I'm gonna cancel out of this dialog because I made no changes I'm gonna right-click and then I'm gonna say go ahead and analyze and if assuming I have an internet connection because this does rely on internet connection and I could doesn't it it found the Internet it was just fine if it doesn't have it connection then you're going to have to find that before this works because it's real time it looks it up right away so now what I'm going to do is open the report and it's going to open because I actually had an option in that dialog that it would open in Excel right so that's how it knows to open this and it's a little small for being on screen here so let me just make it a tiny bit bigger and what we know now is that the dotnet core it's a hundred percent compatible with that dotnet framework and I click this so up at the bar at the top you'll see that this is dotnet framework right there click that this is the dotnet framework dotnet standard 1.4 1.5 and 1.6 this is dotnet standard 1.6 and dotnet standard - oh okay so you can see that's 100% compliant with - and not the others because 2 contains more than the other sitting right so something's going on here and you're going okay so that's not very helpful yet should Cori I can't fix my bursting but it I can't x-men don't know what the exact question you asked which is how do I know what I need to target I've got code and I want to know what I could target I do know that now and I know that I can target dotnet standard 2.0 right now out of the box and code as it exists no changes okay but the question I'm probably going to want to ask if I'm interested in targeting something lower is yeah what did I do right where did I mess up where did I cause a problem and so you find that on the details tab so when I switch to the details tab and again I'm going to click this up just a little bit not that far see if I can't get it we'll see if I can do that let me just use this mouse over here see if I can get a little bit better at this okay that's probably good okay so now what we can see is that the description attribute in the category attribute each of which was used twice in the sample is what's the problem and I can then go over to here and find out where it came in so in dotnet core and dotnet core it came in in 2.0 because in the.net core column it says supported in 2.0 and above in the.net full framework it was supported in 1.1 and above okay I haven't seen anything that's one point now it made one point one maybe the baseline and then for dotnet standard it says it's supported 2.0 and above which is exactly what the previous page told us is that we need to go to what is it that is supported join operators no join operators is the name of my assembly yeah okay that's the name of my so let's go back we're talking about it so it does not tell me the line of code it simply tells me what I'm doing so now I can go and look for where I'm using the description attribute and the category attribute and that's what I know I have to pull out in my app so I could just use a search or something to find this okay okay okay so now I know what it is I'm using I love doing feature requests there if I could could actually know the lines of code that and then compiling it would show me the actual line red yellow green squiggly is exactly code so I realist in the task list yeah cool that would be that would be great if you want that one way to do that is to try to target what it is that you're interested in and then if you target it and it doesn't work out then you're going to be able to go straight to that code and then this one I might do that for this application it doesn't seem like it's going to be a huge wall of problems but now I know if I bring my application up in here and you might want even run a unique to find out how many different things you're using and just how big the jobs going to be to take your application into the dotnet standard or anything else you saw that list you can check out in it I mean there's a bazillion different frameworks that you can select there to see how your code lines up with and you can take code you've currently you've previously written right correct take you know go and find representative samples of code you've already written mm-hmm put it into a dotnet standard library or run the analyzer on it don't you move in yeah you don't have to move it yet yeah and then when you discover that there are hopefully fewer but maybe more incompatibilities than you thought then you could actually that is a dotnet standard library try to compile it and go see what code doesn't run if it's too much then you then you have the choice of either not doing it or figuring out how to accomplish the same thing with code that is supported correct and and I would suggest that just about everyone who already has a class library should think about doing this because it gives them information for that moment that their boss or somebody says oh I heard about this dotnet core thing and if you know that man you've got problems and you already know that then you know just wave off the conversation and if you know hey we don't think we're that far then you can say and we might be able to do that but the problem is going to be what we're going to do on our on our UI side because we don't have cross-platform UI we have that is very specific to what you're doing and so if you're on if you're running xamarin and then that's great and the Samer can call into a class library and then you WP or WinForms or web forms can call into the same library which can see a scenario you have a desktop client application whether it's uwp or WPF or WinForms or you've got a web app with middle tier code and now someone says we want to put a mobile front end on that let's reuse the logic exactly exactly that could easily happen and hopefully does easily happen that is absolutely what dotnet standard is designed to do this makes it a lot easier for you to target that scenario dönitz standard is the set up to target the scenario and there's these tools that are set up to make it easy for you to first of all just assess it's just I have no idea I've no idea how I sit do I have to convert and then see what goes wrong and fight through that or is there a way that you can just in just a couple of minutes give me a report which is what the portability analyzers for most people it's going to take longer to install and run across there okay so it's a pretty fast tool so there's one more thing that's also available in the analyzers which I'll show you real quick which is if I can close that okay there's something else I also have installed which is just an analyzer and analyzers are installed per project where the tool I just showed because it's actually a visual studio tool first of all doesn't run in code sorry and second of all it does it's not per project it's always available after you install it but here I have an analyzer I mean just get that open here if I go under references and I go under analyzers I have one installed which is called the compatibility analyzer I'll move that over something to see it it's a compatibility analyzer I get that off a new gap because that's where we get analyzers and so now if I use a great variable name I use my favorite variable name uh-huh and like I'm going to say new web client that happens to be a deprecated API so I can find out that it's needed in what its deprecated in dotnet framework okay okay so dotnet standard doesn't have deprecated things they're not all the definitions got left behind so now I can hover over that and I can see that that's that's deprecated and it shows up on both the VAR and the the new because the VAR is effectively telling me web client again so in both cases it's a deprecated type so those are the three big tools for helping you stay in the rails of what you really mean to be doing so that's an interesting thing to do as you're writing if you're writing currently writing code that's not targeting standard yet but you want to prepare yourself for a future where you might get this analyzer on right it's a green squiggly it'll still come trial and you're told as you're writing code guess what this isn't going to work and don't assume it will work perfectly well targeting the whole framework which you're currently doing your apps gonna run but it's letting you know that the code you're writing is not compatible with dotnet standard and it's gonna it's not going to show you everything that's not compatible with diagnose that it will show you all the deprecated stuff is a big chunk okay so if you put WinForms code in here that would not be compatible with on its standard but you wouldn't get a green squiggly because you would still be targeting dotnet full framework to get the ok norms there all right okay so now the big gnarly table that everybody shows but not only tailor yes I do okay well let's come over here to and open a new browser window because I want to actually kind of show people how to find this as well okay because we'll put some links up yes well you know we're not always they're not always going to come back here and so if you just say dotnet standard version table okay that's pretty easy if you hit enter there you will see something in the docs yeah you get some tables too that's okay you get some tables but it's this standard that versions empty yeah the dotnet standard any thought that we didn't go far enough making net Mouse so we had to make Mouse dotnet so we literally made table dot yeah all right okay do you all see the pretty one no you want to see the ugly one is there a pretty one there's a prettier one let's see the pretty one it's right up here with this little tiny lighting is this Internet let's go to the interactive let's just get colors okay okay so alright mystified by this one is the other one by now less so this conversation several times yeah okay why what is this telling me what do I do with this besides go get some aspirin okay well this is not as bad as it looks although I do understand that on first blush this is actually looks pretty crazy so the first thing is that I dice just like to say that by default dotnet standard 2.0 is green good to go okay so dotnet standard 2.0 is really where a lot of things came together the platform support dotnet stain or two dot oh that's the one that was based on these evaluations of what real code looked like it wasn't like what somebody thought was going to happen a lot of stuff happened for dotnet Stan or 2.0 to sort of be the place to be if you can be okay so for you you're writing winforms WPF apps and you're just interested in what full frameworks you can run on other than that you don't care right you're not worried about reach you're only worried about where you're at at this moment so if you are on dotnet full framework 4.6.1 or above you're good to go okay because 4.6.1 is in the table next to framework under two so you can target dotnet Stan or to not uh assuming that your you that you were running the actual framework on your production machine is dotnet full framework 4.6.1 or above but not everything in 4.6.1 is in standard 2.0 right but dotnet standard 2.0 is supported by full framework 4.6.1 okay so if you if so if your oh I see so if you yeah so if you let me let me say this yes come correct so if you've targeted down to standard 2.0 and on the machine you have 4.6.1 it will work it will work I want you back at your 5:1 on the machine there are potentially things that you wrote - that aren't in there but wouldn't your compiler of caught that in the first place no because your compiler is looking at net standard 2.0 DLL the reference DLL I showed you earlier so it's compiling against net standard DLL 2.0 and dotnet full framework 4.5 dot one does not have a net standard DLL 2.0 it has a net standard DLL 1.2 and it says I can't even start I can't do anything I try again and so if you want to stand for whatever reason if you need to target dotnet full framework 4.5 dot 1 you would have to use dotnet standard 1.2 okay and for most people at that point I'd say what are you going to gain from it if you can target 2.0 then you're sort of in this nice friendly space but it's much more painful I'll show you a little bit about what that pain looks like so we're going back to 1.2 oops I need to be that's not what I needed to click so we're going to try it again we're going to go here and we're going to say 1.2 ok so now you see all of the things that you can run on there's a lot of things now that you can actually run on ok but do you remember what the blue bar at the top looked like before was all the way across right that's like just a bar graph of what's available to you so you have 30% of your api's are available 70% are not available so you're gonna have problems you're gonna run into something you're doing that is not supported and so if you have a compelling reason to do that hmm I can give you one compelling reason if you were a library author planning on some putting something on nougat right and you wanted as many people as possible to use yours yeah and you tested with the analyzer I showed or some other way you just targeted to see what happened and you said hey you know what I can do it no problem everything I want is in there then at that point you can target dotnet standard 1.2 have the broadest possible reach and you haven't hurt yourself right but for you writing your win forms or WPF ever I'm going to say what are you gaining you know why you trying to do this if you're back here so 2.0 is really the the the sweet spot and I do want to just say with a little caveat that 4.6.1 up until 4.7 the the way that the the location of things were shifting around on a couple of pieces inside the full framework that caused a bit of headaches for dotnet standard so the dotnet standard DLL had to be aligned with what was on the machine there was a couple of things that it just wasn't quite wasn't quite as solid as you want your production machines to be so you might want to still target dotnet full framework 4.6.1 or for that 6.2 or 4.7 I guess and then use that analyzer to see if you're ready to go and then maybe look at actually targeting net standard in like the 4.7 one a 4.7 - time frame because these these shifts around that needed to happen just to get us fully on to net standard they're done and so there's a little bit of time in there where the it was just not as solid as you probably want a production machine it's not I don't want to scare you on that it's just that some things move from out of box to in box and that was a challenge for dotnet standard because it was here and now it's there and a few things like that just wound up with it with a few problems and just keeping those problems on production is a great idea so let's let's close with how often dotnet standard will change all of the things under here constantly changing there's a 4 7 foot there's a 2 1 core coming out iOS 11 is out in Visual Studio will have support for it potentially by the time this post if not even after that Android 9 is gonna be out eventually you WP there's a new version which is a couple weeks away or so I'm told some of these other things don't change well the dotnet standard change every time one of these changes okay that's a great question so first of all let's be clear that all of those numbers are anything higher than that will also support so immediately right now you know 4:71 2.1 of dotnet core which is available in preview right now all of those things support dotnet standard - oh right now so all of the numbers in that column is those or anything greater so when iOS 11 comes out then there there may be a little bit of work that has to happen if there's again these things when things move that standard has to point to the right spot the net standard dll on you know that might need a little bit of tweaking I can't promise that won't happen but people working very hard for that to be smooth and not so is that the standard 2.0 one or a 2.1 because one of the interesting things is if you remember all of the bracket curly brackets are empty in the reference dll okay and so Dinah standard itself will never have a patch release because there's no code to patch it only has changes to its API surface layer because it is just an API services so that standard only needs to change when there are api's that need to be added to it that yes it doesn't necessarily happen just because iOS went from version 10 to 11 or Android went from 8 to 9 or UWP went from 10 oh 16 to 99 to 0 17 blah blah blah right and so the the interesting thing about that especially for right now because we're you know in a lot of conversions in so many numbers in the air and it's all very confusing is that dotnet core is in preview on dotnet core 2.1 it's moving forward but there haven't been any changes right now to dot it standard so dotnet standard is independent of dotnet core and it will stay on dot nest an or two dot o-- for the next in the next foreseeable future the next few months at least until there's something so we have span now in dotnet core updated versions 2.1 of dotnet court has span and all of its friends and or to oh it is not in standard to okay but that's the kind of thing that would push dotnet standard into net Stan or 2.1 and there's going to be a little bit of a I think a conversation about whether dotnet standard should be aggressive in versioning and as soon as somebody has an idea when we look at uses yeah why don't we go look at percentage of existing apps today use span it's probably a less than system data dot link so I think there's priests over time but I think there's two pieces that are super important one is exactly that right and the other is remembered inot standard in and of itself does not matter it only matters from platforms supported so if you create a dotnet Stan or two dot one and the only thing in the planet that supports it is dotnet core 2.1 did you gain anything right because nobody else can use it so it's not just people using span but it's also other frameworks being ready to support span or you know whatever the API is I'm just using that as an example and so it's when those kinds of things start happening that we want to see dotnet standard evolve so the new features that I could use cross-platform if you just let me our end on it stand or have the ability to extend it because I believe Dutton it core there's the ability to extend it to call missing pieces of the framework is that correct so there's a couple of things you might be referring to there one is that there's a compatibility pack which is Miss named which is Miss named I just want to say that I had nothing to do with his name it's called a windows compatibility right so you'd think it was just for Windows wouldn't do ya know about half of it will also run cross-platform code and half of it will that is a way of adding things that aren't in core and call I'm your coach so you can potentially see something similar for standard you want span that's not in standard yet here's a way to kind of shove it in on the side so that might happen in the nature right now it that would wind up being something through a through new get that you would be getting a span that made sense in your world and as of today that's that's not something that I see out there at all I think that as we get into done in standard I mean our first step is just to explain this crazy thing and have people understand it and understand why they care and then we'll see how it evolves as we see what people ask for is they start really hopefully embracing it and embracing a way that there's no reason to write your application class libraries anymore that are specific to a framework unless there is a reason right so there's no they used to be that was the only way to write it and that was not a problem when our frameworks were like all over the map and hitting really different targets so Windows Phone versus pro framework those are really different but now we have dotnet core and dotnet full framework and they both run on a Windows machine and you're already figuring out which of those you want to do and dotnet standard gives you a way to say that decision can be a kind of temporary decision it doesn't have to be a locked in stone decision for your class libraries cool so yes we're out today right thank you I think this I think this cleared up a lot of the confusion I hope it did I think it's good to see you confused if I'm confused you can imagine viewers are - it's not just about me it's not just about not just about you Robert I hope you enjoyed that and we will see you next time on visual studio toolbox [Music]