What's the difference between:
GuzzleHttp
ReactPHP
Amphp
How they differ and what would be typical use case to use with?
The main difference between those is that Guzzle is an HTTP client, while Amp and ReactPHP are generic async / event loop libraries. Both of these offer HTTP clients based on the core event loop they offer. Those are amphp/artax and reactphp/http-client.
Now, the difference between those and Guzzle is that those can do other things concurrently that are not HTTP requests. That is, because the user has full control over the event loop and can register own I/O watchers and timers, while the event loop that Guzzle uses is hidden from the user inside Curl.
If you just want to make a few concurrent HTTP requests, the decision mainly boils down to the API you like and a performance consideration maybe. If you want to do other I/O related things concurrently, use Amp or ReactPHP. If you want to stream your bodies, I'd suggest against using Guzzle, too.
Hey ReactPHP core team member here. Both ReactPHP and Amp assume you're building an app with an event loop. If you just want to do a bunch of async requests and then continue, I would suggest using Guzzle's async requests: http://docs.guzzlephp.org/en/stable/quickstart.html#async-requests
If how ever you want to dive deeper into async request I suggest https://github.com/clue/php-buzz-react which gives you more control over the process plus it supports PSR-7.
Related
can any one explain. when to use Synchronous and Asynchronous request with example.enter code here
Generally speaking, asynchronous requests do not block the running environment until they get a response. This keeps your UI responsive while waiting for the response, and enables your user to use it. With synchronous requests, the UI would feel like it would be frozen.
I would say that while developing a web application, you would probably use asynchronous requests 99.9% of time.
From a software engineering stand of point, synchronous code is using one process, while asynchronous code executes a concurrent process. That is exactly how your UI is enabled to be responsive. It's like as if the asynchronous code ran as another program, if you will.
I have a scenario in my existing application where on the click of a Save button a Javascript function is called. This javascript function internally makes 4-5 asynchronous calls to webservices.For some reasons we have big javascript files now with lot of business logic. Also we are facing performance issues in the application. To reduce the number of XHR calls we are making to the server, we thought of consolidating these calls on the server side and just make a single call from our Javascript.
On the server side we are using Async Await to make this calls asynchronous.So we have created a wrapper service with one method which now calls different service methods using SendAsync method exposed by HTTPClient.
Our underlying services are all synchronous and to achieve asynchronous functionality we used HTTPClient. We measured performance and it shows considerable gain.
But, one of our colleague pointed out that we will actually have an overhead of serialization and Deserialization as well as we are originating now other webservice calls from server which will ultimately run synchronously.So why not directly call the methods instead of new HTTP calls.
ow our methods are all synchronous and to make them asynchronous we will have to use Tasks which will again be overhead.
Both the approaches will be overhead but we see the making new HTTP requests using async await more inline with the microservices concept.
There is a debate and I would like to know other thoughts.
My two-cents:
The approach of aggregating the information on the server side is good.
From my point of view the use of HTTPClient internally on the server side is a solution only if you want to connect to a legacy service and you do not have the ability to integrate it directly. HTTPClient is simple to use and robust, but it's technically a lot more overhead than using a Task (think of error handling, serialisation, testing, network/socket-resources).
A Task is also nice, since it allows proper cancelation, which HTTPClient cannot achieve (HTTPClient can only close the socket, other end could still block resources).
On top of the general resource aspect, the use of Futures makes the Task a perfect match:
https://msdn.microsoft.com/en-us/library/ff963556.aspx
Do I need to do anything to make all requests asynchronous or are they automatically handled that way?
I ran some tests and it appears that each request comes in on its own thread, but I figure better to ask as I might have tested wrong.
Update: (I have a bad habit of not explaining fully - sorry) Here's my concern. A client browser makes a REST request to my server of http://data.domain/com/employee_database/?query=state:Colorado. That comes in to the appropriate method in the controller. That method queries the database and returns an object which is then turned into a JSON structure and returned to the calling app.
Now let's say 10,000 clients all make a similar query to the same server. So I have 10,000 requests coming in at once. Will my controller method be called simultaneously in 10,000 distinct threads? Or must the first request return before the second request is called?
I'm not asking about the code in my handler method having asynchronous components. For my case the request becomes a single SQL query so the code has nothing that can be handled asynchronously. And until I get the requested data, I can't return from the method.
No REST is not async by default. the request are handled synchronously. However, your web server (IIS) has a number of max threads setting which can work at the same time, and it maintains a queue of the request received. So, the request goes in the queue and if a thread is available it gets executed else, the request waits in the IIS queue till a thread is available
I think you should be using async IO/operations such as database calls in your case. Yes in Web Api, every request has its own thread, but threads can run out if there are many consecutive requests. Also threads use memory so if your api gets hit by too many request it may put pressure on your system.
The benefit of using async over sync is that you use your system resources wisely. Instead of blocking the thread while it is waiting for the database call to complete in sync implementation, the async will free the thread to handle more requests or assign it what ever process needs a thread. Once IO (database) call completes, another thread will take it from there and continue with the implementation. Async will also make your api run faster if your IO operations take longer to complete.
To be honest, your question is not very clear. If you are making an HTTP GET using HttpClient, say the GetAsync method, request is fired and you can do whatever you want in your thread until the time you get the response back. So, this request is asynchronous. If you are asking about the server side, which handles this request (assuming it is ASP.NET Web API), then asynchronous or not is up to how you implemented your web API. If your action method, does three things, say 1, 2, and 3 one after the other synchronously in blocking mode, the same thread is going to the service the request. On the other hand, say #2 above is a call to a web service and it is an HTTP call. Now, if you use HttpClient and you make an asynchronous call, you can get into a situation where one request is serviced by more than one thread. For that to happen, you should have made the HTTP call from your action method asynchronously and used async keyword. In that case, when you call await inside the action method, your action method execution returns and the thread servicing your request is free to service some other request and ultimately when the response is available, the same or some other thread will continue from where it was left off previously. Long boring answer, perhaps but difficult to explain just through words by typing, I guess. Hope you get some clarity.
UPDATE:
Your action method will execute in parallel in 10,000 threads (ideally). Why I'm saying ideally is because a CLR thread pool having 10,000 threads is not typical and probably impractical as well. There are physical limits as well as limits imposed by the framework as well but I guess the answer to your question is that the requests will be serviced in parallel. The correct term here will be 'parallel' but not 'async'.
Whether it is sync or async is your choice. You choose by the way to write your action. If you return a Task, and also use async IO under the hood, it is async. In other cases it is synchronous.
Don't feel tempted to slap async on your action and use Task.Run. That is async-over-sync (a known anti-pattern). It must be truly async all the way down to the OS kernel.
No framework can make sync IO automatically async, so it cannot happen under the hood. Async IO is callback-based which is a severe change in programming model.
This does not answer what you should do of course. That would be a new question.
We have an application that hits a web service successfully, and the data returned updates our DB. What I'm trying to do is allow the user to continue using other parts of our web app while the web service processes their request and returns the necessary data.
Is this asynchronous processing? I've seen some console app samples on the msdn site, but considering this is a web form using a browser I'm not sure those samples apply. What if the user closes the browser window mid request? Currently we're using the Message Queue which "waits" for the web service to respond then handles the DB update, but we'd really like to get rid of that.
I'm (obviously) new to async requests and could use some help figuring this out. Does anyone have some code samples or pertinent articles I could check out?
Yes, what you're describing is async processing.
The best solution depends to some degree on the nature of the web services call and how you want to handle the results. A few tips that might help:
One approach is to send a request from the initial web request to a background thread. This works best if your users don't need to see the results of the call as soon as it completes.
Another approach is to have your server-side code make an async web services call. This is the way to go if your users do need to see the results. The advantage of an async call on the server side is that it doesn't tie up an ASP.NET worker thread waiting for results (which can seriously impair scalability)
Your server-side code can be structured either as a web page (*.aspx) or a WCF service, depending on what you want to have it return. Both forms support async.
From the client, you can use an async XMLHTTP request (Ajax). That way, you will receive a notification event when the call completes.
Another approach for long-running tasks is to write them to a persistent queue using Service Broker. This works best for things that you'd like users to be able to start and then walk away from and see the results later, with an assurance that the task will be completed.
In case it helps, I cover each of these techniques in detail in my book, along with code examples: Ultra-Fast ASP.NET.
If you're not blocking for a method return you're doing asychronous processing. Have a look at Dino Esposito's article on using AJAX for server task checking.
You can perform asynchronous web service calls using both Web Service Enhancements (WSE) and Windows Communication Foundation (WCF) in your C# code. WSE is discontinued, so its use is not recommended. Generically speaking, if you were to terminate program execution in the middle of an asynchronous call before the response returned, nothing bad would happen; the client would simply not process the result, but the web service would still be able to perform its processing to completion.
If your client web application is responsible for updating the DB, then without anything else in your client code, quitting in the middle of an asynchronous operation would mean that the DB was not updated. However, you could add some code to your client application that prevented the browser from quitting entirely while it is waiting for an asynchronous response while preventing new web service calls from being run after Close is called (using Javascript).
You have 2 distinct communications here: (1) from web browser to web application and (2) from web application to web service.
diagram http://img697.imageshack.us/img697/6713/diagramo.png
There is no point of making (2) asynchronous: you still would have to wait for web service to finish processing request. If you end HTTP request from browser to web application the client would have no clue what the result of request was.
It is much better to make asynchronous request from web browser to your web application. Ajax is ideal for that. In fact, that's what it was created for. Here's couple of links to get you started:
jQuery Ajax
ASP.NET AJAX
What is the difference between Web Services Asynchronous Call and Asynchronous Task's.
We are working an a ASP.NET application that requires to make a call to a Web Service Method that will process thousand rows of data. This process usually takes between 2 to 3 minutes (maybe more maybe less it depends of the amount of Data). So we run all the time in Timeout's on that specific page.
So we decided to go in rout of calling this Web Service Method Asynchronously, but we had a conflict caused by HTTP handler of one of the UI component's that we are using. Well lucky on that case we could remove the page from the httphandler directives.
So far no issues, but here it comes the question, a coworker find out that we can use instead of Asynchronous Webs Services Call, wrap a Synchronous call in a Asynchronous Task in the ASP.NET page and be able to keep the directives to the component, and execute the Web Service Method with out getting a Timeout.
So now my concern is what kind of issues we can find using Asynchronous Task's instead of an Asynchronous Call.
Thank you in advance.
Web services should not be used in this manner by the way. There's a reason HTTP timeouts are so low. You should have the Web service trigger the task either by setting a flag in the DB that an actual service picks up on or the web service should spawn a process.
If I understand your scenario, there should be no issues. In both cases, your page is asynchronous. In both cases, you don't wait for the service to complete - you give up the request thread while the service is running. In both cases, your page takes the same amount of time to execute as it would if you had called the service synchronously.