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.
Related
So i want to develop a simple web application, which will basically be a basic form which on submission will allow to make an external api request. So are there any application designers that can allow to do that with minimalistic code. Appian for example has an interface/application designer that lets you drag and drop a UI interface and build a workflow, make api calls externally or to a database. So like that are there any other apps that allow to do something similar (make api calls/build ui easily/store in databse)? Any other suggestions are also welcome!
It heavily depends on the API as well as the kind of task you´re trying to achieve.
Here´s just a few examples and considerations. (All the below supposes that we´re talking about Web-Based APIs).
If the API requires authentication of some sort and the user authenticates himself: A simple HTTP file with JavaScript to send the request will do the job
If the API requires authentication but you authenticate for all the users: You will need a backend application that does the API request since you need something secure where you can put your Auth-Details for the API. Classic PHP or NodeJS in combination with a served HTTP file for the form itself would work without any JavaScript (depends on the API definitions)
If the API does not require authentication maybe a simple HTML form would work
If you want to write to a database you can have a look at something like https://directus.io/. They allow building a database with a UI and they automatically generate a Web-API which you can then feed by your forms. If the end-user is known to you Directus actually allows users to log in and fill the database with forms that you can visually design but this is rather for employees entering data into an internal database than customers submitting their contact data to you
From my personal experience, all the UI-Tools that promise to integrate with REST APIs make it really hard to do so since every API is different and there is no real standard for them.
I'm currently working on an analytics webapp with a react frontend and node (express) backend.
Describing the functionality in a nutshell:
A user will be able to login on the website, search for a YouTube username and then the YouTube API is called, the data will be stored in a mysql db via my express API and also the data will be used to calucalte some statistics which afterwards are displayed in a dashboard.
Now I was wondering if I should:
Call the YouTube API from the frontend, i.e. inside my react code, do the calculations display them and and then store it in the DB via my express API.
Or, from the react app call an endpoint in my express API that will then call the YouTube API, store the data in the DB and then pass on the data to my react app.
Are there any best practices or up-/downsides to either approach?
When answering questions like these, it's important to remember that the client-side is different for each and every user that visits your website, their internet speed, their GPU & CPU power, etc., but the server is most commonly held in a stable container and much more powerful than a client.
The proper way would be the following:
1. Obtain a search query from a client
Meaning you should get the user's search query from an input, or any other form of control (text area, checkbox, etc.), this way client is doing the least business logic, as it should. The client should always focus more on UI / UX rather than business logic.
2. Send query to the server
Let the server use the query you've just obtained from client, call the youtube api from the server (either explicitly using Axios, or find a node.js youtube library), and do all the necessary calculation on the backend
3. Send processed data to the client
Let client receive the data in the form which is ready for use (iterations, mappings, etc.) - again separating concerns, server - business logic, client - UI / UX
Now to be fair, the example you have will most commonly be done all on the client-side, since it is not as computationally heavy as other enterprise examples, but this is a good rule to follow for big projects, and no one would really complain if you did it this way, since it would be the proper way.
Have small app (My first Node js App), where I want add changing real-time content.
For example I have a common url which have list of content link, when user click on particular link it will open its correspondence link.
I have teacher and student role in the app so if teacher open the specific content(From the common url page) then it will automatically open that content for all student who have common url.
Please give me any Idea to implement this functionality and please tell me any plugin who have same functionality for real time content change.
One way, probably the easiest would be to use websockets, an easily manageable choice is socket.io npm package. What makes websockets different from http requests is the direction of the data flow. While http is pull based, meaning that a request has to be made to the server in order to get a response, websockets - once the connection is established - are or at least can be push based, meaning that the server could push out content without having to get a request from the client. In your situation, the teacher and the studens would all have an active websocket connection with the server. When the teacher clicked on a certain view, it would push the view’s data requirements to the students without any interaction from their side and the view would update on their screens according to the pushed data.
Look into how websockets work and try to experiment with a basic socket.io setup.
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!
(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.