How can Socket.io and RESTFul work together? - node.js

(I'm not familiar to RESTFul, please correct me if my concept is wrong)
In RESTFul architecture, we map every action to an URL. If I click "post a article", may it's actually URL http://example.com/ and some data action=post&content=blahblah.
If I want to post, but not refresh the whole web page, I can use javascript's XMLHTTPRequest. I post it and then get it's content and insert it to a div in my page. These action is all asynchronous.
Then I know there is something named WebSocket and it's wrapper socket.io. It use "message" to communicate between client and server. When I click "post" the client just call socket.send(data) and wait for server's client.send(data). It's magical. But how about URL?
It's possible to use the two model both without repeating myself? In other word, every action has it's URL, and some of them can interact with user real-timely(by socket.io?)
Moreover, should I do this? In a very interactive web program(ex. games), the RESTFul is still meaningful?

You're defining a handler for actions that map to REST over http. POST and GET generally refer to update and query over an entity. There's absolutely no reason you can't just define a handler for generic versions of these CRUD operations that can be used in both contexts. The way I generally do this is by introducing the concept of a 'route' to the real-time transport, and mapping those back to the same CRUD handlers.
You have a session, you can impose the same ACL, etc.
 +---------------------------------+
 |                                 |
 |      BROWSER                    |
 |                                 |
 +--+--^-------------------+---^---+
    |  |                   |   |
    |  |                   |   |
 +--v--+---+            +--v---+---+
 |         |            |          |
 | HTTP    |            | SOCKET.IO|
 +--+---^--+            +--+---^---+
    |   |                  |   |
 +--v---+------------------v---+---+
 |                                 |
 |        ROUTING/PUBSUB           |
 +-+--^-------+--^-------+--^------+
   |  |       |  |       |  |
 +-v--+--+  +-v--+--+  +-v--+-+
 |       |  |       |  |      |
 | USERS |  | ITEMS |  |ETC   |
 +-------+  +-------+  +------+
     ENTITY CRUD HANDLERS

I posted this on my blog recently:
Designing a CRUD API for WebSockets
When building Weld, we are using both REST and WebSockets (Socket.io). Three observations on WebSockets:
Since WebSockets are so free-form, you can name events how you want but it will eventually be impossible to debug.
WebSockets don’t have the request/response form of HTTP so sometimes it can be difficult to tell where an event is coming from, or going to.
It would be nice if the WebSockets could fit into the existing MVC structure in the app, preferably using the same controllers as the REST API.
My solution:
I have two routing files on my server: routes-rest.js and routes-sockets.js
My events look like this example: "AppServer/user/create".
I use forward slashes (“/”) to make the events look like routing paths.
The first string is the target (~”host name” if this actually was a path).
The second string is the model.
The third string is the CRUD verb: i.e. create, read, update, delete.

Related

What is the difference (if any) between a route and an endpoint in the context of a RESTful API?

Question
I have a probably rather simple question, but I'm unable to find an answer with nice explanations:
What is the difference (if any) between a route and an endpoint in the context of a RESTful API developed within a Node.js / Express application (but these concepts may be broader?!)?
(Does it relate to URLs in some way?)
Example
For example, in this article: https://medium.com/#purposenigeria/build-a-restful-api-with-node-js-and-express-js-d7e59c7a3dfb we can read:
We imported express which we installed at the beginning of the course, app.get makes a get request to the server with the route/endpoint provided as the first parameter, the endpoint is meant to return all the todos in the database.
These concepts are used interchangeably, which makes me confused.
(please note that I'm a 100% beginner with REST API, nodejs and express but I try to do my best to learn).
Edit
The two first answers chronologically speaking make me even more confused as they are perfectly antagonistic.
3 different concepts here:
Resource: {id: 42, type: employee, company: 5}
Route: localhost:8080/employees/42
Endpoint: GET localhost:8080/employees/42
You can have different endpoints for the same route, such as DELETE localhost:8080/employees/42. So endpoints are basically actions.
Also you can access the same resource by different routes such as localhost:8080/companies/5/employees/42. So a route is a way to locate a resource.
Read more: Endpoint vs. route
Read more: Endpoint vs. resource
Route
URI path used to access the available endpoints.
example: http://www.mywebsite.com/
Endpoint
performs a specific action.
has one or more parameter(s).
returns back data.
example: GET http://www.mywebsite.com/Products
A Route is the URI, and the Endpoint is the action performed on the URI.
Routes and endpoints are associated concepts - you can't really have one without the other.
What is an endpoint?
Generally speaking, an "endpoint" is one end of a communication channel where one system interacts with another system. This term is also used similarly in networking.
For a typical web API, endpoints are URLs, and they are described in the API's documentation so programmers know how to use/consume them. For example, a particular web API may have this endpoint:
GET https://my-api.com/Library/Books
This would return a list of all books in the library.
What is a route?
A "route" is typically code that matches incoming request paths to resources. In other words, it defines the URL and what code will be executed. A route path might contain regular expressions, patterns, parameters, and involve validation. For example, consider this route path:
"{controller}/{action}/{id?}"
In ASP.NET, pattern matching is applied, so GET https://my-api.com/Library/Books/341 would call the Books public method on the Library class, passing a parameter of 341. Routing frameworks can be very flexible and versatile.
The simplest example of an endpoint is to put a file you want to be consumed (say data.json) inside the public_html folder of your web server. It can be reached by GET https://my-api.com/data.json. The routing is handled by the web server out of the box and no routing code is required.
Some good things to read next:
Express.js - Routing
Wordpress Developer Resources - Routes and Endpoints
When to use "client-side routing" or "server-side routing"?
Endpoints are basically use to perform specific task and return data and endpoints are kind of part of a route.
For example is route and this is also a route but here both of them are returning different data not he same so, we can say that the last two parameter here is kind of end point means the id and question string.
endpoints:
/56075017/difference-between-route-and-endpoint
/56040846/how-to-use-the-classweight-option-of-model-fit-in-tensorflow-js
route:
https://stackoverflow.com/questions/56075017/difference-between-route-and-endpoint
https://stackoverflow.com/questions/56040846/how-to-use-the-classweight-option-of-model-fit-in-tensorflow-js
In this example: http://example.com/my-website/comments/123:
Route:
my-website/comments/123
Endpoints: (a fancy word for a URL with an action)
GET http://example.com/my-website/comments/123. returns the comment data.
DELETE http://example.com/my-website/comments/123. deletes the comment and returns the now-deleted comment data.

why should I not use MVC Jsonresult instead of apicontroller get method

I have developed an application which was MVC application. It has a requirement that the application will return json data for one get request.
So I have added apicontroller and created a get method to return json data.
So far so good. but then I thought, is it really needed to add apicontroller to create just one get method.
I started exploring and googling what is the difference other than content negotiation. Got lots of answers and articles but non of them were satisfactory.
So here is the actual confusion, why can't I just create a method in the MVC controller with JsonResponse and return the json data(Which I know only is need for my requirement, but other application on different domain will consume it).
Can anyone convince me why should I use apicontroller instead of MVC JsonResponse for my requirement or should I not be using apicontroller at all.
apology if there is any mistake.
If I get it right the question is Can we use MVC action to serve json content answer is yes! Is it okay to use Json Result? answer is It depends where do you want to consume it
Say I am an in a Web Environment where I have no need for the APIs (that means I am not going to serve my data to multiple clients) If that's the scenario where only your View is going to consume data returned from your Action Method you are good to go. An Action returning a Json Result is basically an Action Result and that's what it is made for.
but If you are in a REST scenario and you need your backend to serve your data to the client de facto standard is to use an independent Web API for that.
Controllers' main responsibility should be to work as an intermediary between your View and Model and whatever service layer you want to bring inside it. on the other hand, Web APIs are data-driven there only purpose is to serve data (use them if you need them)
Web APIs are good cause they give you the flexibility of serving the data to possibly any client that might need it. That's what I would pick if I am starting from scratch but if I only need to serve data to one client Controller Action methods will be way to go.
Hope this helps.

Extending existing RESTful API using Node.js

I am currently running a web service on an Apache Tomcat servlet container. The web service has a base URL and exposes my applications data using the following structure:
http://[hostname]:[port]/path/to/root/[db_table_name]/[primary_key]?fields=name,...
An HTTP GET call to a URL like the one above would return a JSON formatted string.
Though the documentation for my application describes this as a RESTful API, I am confused because I was under the impression that true RESTful APIs do not use query strings. Rather, as I understand it, a true restful API provides a uniform structure, in the form of resource endpoints.
My questions relate to how I can create a custom API to leverage the existing API using Node.js. I do not want to rewrite the application logic or database calls; I just need to know how I can create the API calls using Node.js (possibly using Express or some other framework) and let the existing API handle the request.
For example, I could write Node.js code using the Express module that has several routes, these routes would handle client requests that in turn would call the existing API (i.e. /path/to/root/[table_name]/[pk]... and return the response.
If my Apache Tomcat server is listening on port 8080, how would I deploy my Node.js server to listen on another port and then redirect requests to the existing WS URL on port 8080.
Does the Express framework support explicitly specifying a root path (such as http://localhost:3000/path/to/root/[table_name]/[pk]) as the default root path?
Finally, I know REST APIs support CRUD operations. In the case of a POST method, does Express (or Node.js) have built-in logic to handle duplicate POST requests so that duplicate records don't get created in the database.
I'm reading through different article and tutorials on REST but I think I'm missing something. Any information or advice that can take me in the right direction would be much appreciated.
there's a lot to cover here but I'll try to cover your three questions. Since you have mentioned using Express I will answer assuming that Express is the framework you are using.
If you are using Express, you can choose which port to listen to when you start the server, so you can choose any port that you like at that point (see here).
If you need to redirect a request you can do so easily with res.redirect() (see here). However, you could also call the other web service directly, retrieve the data and return it to the client instead of redirecting them if you prefer. That would require some more code to make the http requests in node.js though.
I am not 100% sure if this is the answer to your question, but there are ways to add a "base path" or namespace to all of your routes. I found this example where various namespaces are used but in your case you only need one which applies to all routes.
I don't think there is a built-in way to do this. The best I can think of is potentially creating some kind of ID for the request so that if it is sent twice you could use this to check but it's far from ideal.
I would like to add that I'm not sure where the idea that query parameters not being RESTful comes from? I think query parameters are fine because that is how you query! Otherwise you couldn't ask for the right data from your RESTful API. Let's say you have a /posts endpoint and you want to get the posts of a particular user (user ID = 1). The RESTful way to do this would be to issue a GET request to /posts?user=1.
Hope this helps!

Use of OData in a web application instead of other

I read in an article that odata can be used for different combination of clients/servers.
Say I would like to develop a web application where i store data(say information about all mobile products on market) using mongoDB and use python as backend with Bottle framework to access data through browser as GET.
Then i decide to extend web app as android app. i can extend it to android without any code change on server side.
My doubt is does using odata here helps in any way? Say if i want to extend it to other clients?
Yes, you are right, you don't need to change even a single line of code on the server side if you change a client app. OData defines many conventions for the communications between the client and the server. such as:
What the URL looks like if you want to query some data
http://services.odata.org/V4/OData/OData.svc/Products?$filter=ID gt 2&$select=ID,Name,Rating,Price&$orderby=Price desc
Which http method should be used to Create/Retrieve/Update/Delete an entity
Generally speaking, Post for Create, Get for Retrieve, Patch/Put for Update, Delete for Delete.
What the payload looks like.
How to invoke a function/action
As long as the requests conform to these conventions, the server side always returns the predictable responsese regardless whether the clients is a browser or a mobile device.
I also find the examples for the odata:
https://aspnet.codeplex.com/SourceControl/latest#Samples/WebApi/OData/v4/ .
Hope this helps you.

Node.js+Socket.io: Templating # server or browser? Load content via ajax or socket.io?

I already asked a similar question but this one is a bit different/specific:
I'm about to start development of a social community site (for a local user group) with features like timeline, IM/chat, forums, ...
Node.js and socket.io (or now.js) on the backend. jQuery (and maybe backbone.js or similar) on the front end. Content is loaded via socket.io or ajax and navigation via url hash.
There are 2 things where I just can't decide which way to go. I hope here are some people who can provide some good or bad experience.
Templating on server or in browser? I'm not sure if it's better to load a complete html site + live updates (also in html) for timeline, forum posts, IM/chat, ... or use something like a REST api via ajax or socket.io and do the templating on the client site. I've never done that before. You need to download the templates, etc, etc. Has anyone experience in this? There are also 2 ways to implement a rest-like api: E.g. request a forum post, then request the user associated to that post and so on (just like server side MVC) - or - request a forum post and the server answers with all needed information.
Load content via ajax or socket.io? I'm definitively using socket.io or now.js for real-time communication (IM, chat) and pubsub (on mainpage -> subscribe to new timeline updates, on a forum topic -> subscribe to new posts). But should I also load HTML (or provide a REST-like API, see question 1) through the socket? When people open forum posts in tabs (which I usually do a lot) that would mean a lot of socket connections. And I'm not sure how long it takes for a websocket to establish connection.
So there a 4 ways to do this:
HTML via AJAX - probably the most stable way that doesn't need a lot javascript to do the templating - Browser can use open HTTP connections to request stuff.
HTML via socket.io - The websocket must be established to load content (may be slower)
API via AJAX - as it probably needs more requests as HTML via AJAX there might be some HTTP header overhead + you need to authentication in each request- I'm not a friend of too many ajax requests.
API via socket.io - Socket must only be authenticated only once and you can request API objects on the fly. However I would still load templates and js via HTTP for browser caching.
I know this is a huge post but I'm debating for many days now and just can't decide as it would be a lot of work to switch the system once started developing. This is not a public project, it's limited to ~10k-15k local people and thus must not be that perfect, a good opportunity to learn new things in my opinion (I'm completely new to node, classic PHP MVC + jquery dev here).
I think you should use a RESTful api on the backend, let the templating occur just on the frontend (maybe with Backbone) and only use Socket.IO for real realtime stuff (such as chat). It doesn't make any sense to use websockets for something like loading HTML, because it most likely never changes.
So my vote is:
1) HTML via AJAX
2) API via AJAX
3) Realtime communication, such as chat messaging (or other stuff that constantly changes) via Socket.IO
Though there really isn't a definitive answer, as it depends.
If you need to be search engine crawlable, you can NOT rely only on client-side processing. If your individual views are light, and/or you need to support mobile, you should have initial rendering server-side.
Currently, I would suggest using an API that both your client application and server-side can use. If you use node for the server-side rendering you can re-use a lot of the same logic, including the API client.
Going a few steps farther, if you look starting with the Yahoo flux examples project on github, you can use the same logic both client and server-side including rendering with React views. This is not an easy solution, and will take some work.
For interactive elements, server-side rendering can be minimal with your stores pushing an event wiring up via sockjs/socket.io when the client starts for your chat/im bits.
You will have scalability issues when it comes to running across multiple processes and will likely need a pub/sub chain backed by a db for longer re-connect cycles or missed IM messages. There isn't a magic bullet.
Right now, I like flux+react... When Angular2 comes out, it may have a better story for server-side rendering.

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