If to call own api for building the website is a good practice.
Which is the best way to call own api on the same server in a nodejs application?
simply calling the api-methods
using socket.io with emit() and listen it with .on('event', function(){})
install jquery on the server and use the ajax call
or not use at all the own api and rewrite the methods
i'm just confusing. Hope someone can clarify me on this.
If you need to call own API from another process it would be good to use some messaging protocol. ZeroMQ sounds like perfect fit here. It allows to create different patterns of communication between different services in internal networks, and communicate in different ways. Simplest example is Request > Response pattern that is similar to HTTP requests. And it might be a good start point.
Remember that if you using routing system within express, then ZeroMQ solution will not utilize that, it would be able directly communicate, not through HTTP interface. It is much more efficient as well, as HTTP has unnecessary overhead especially for internal communication.
If you still want to use express routing then your option would be to use http.request, which behaves very similar to curl or $.ajax. This function makes HTTP requests, so you can reuse your express routing system.
Related
I am developing an application where there is a dashboard for data insights.
The backend is a set of microservices written in NodeJS express framework, with MySQL backend. The pattern used is the Database-Per-Service pattern, with a message broker in between.
The problem I am facing is, that I have this dashboard that derives data from multiple backend services(Different databases altogether, some are sql, some are nosql and some from graphDB)
I want to avoid multiple queries between front end and backend for this screen. However, I want to avoid a single point of failure as well. I have come up with the following solutions.
Use an API gateway aggregator/composition that makes multiple calls to backend services on behalf of a single frontend request, and then compose all the responses together and send it to the client. However, scaling even one server would require scaling of the gateway itself. Also, it makes the gateway a single point of contact.
Create a facade service, maybe called dashboard service, that issues calls to multiple services in the backend and then composes the responses together and sends a single payload back to the server. However, this creates a synchronous dependency.
I favor approach 2. However, I have a question there as well. Since the services are written in nodeJs, is there a way to enforce time-bound SLAs for each service, and if the service doesn't respond to the facade aggregator, the client shall be returned partial, or cached data? Is there any mechanism for the same?
GraphQL has been designed for this.
You start by defining a global GraphQL schema that covers all the schemas of your microservices. Then you implement the fetchers, that will "populate" the response by querying the appropriate microservices. You can start several instances to do not have a single point of failure. You can return partial responses if you have a timeout (your answer will incluse resolver errors). GraphQL knows how to manage cache.
Honestly, it is a bit confusing at first, but once you got it, it is really simple to extend the schema and include new microservices into it.
I can’t answer on node’s technical implementation but indeed the second approach allows to model the query calls to remote services in a way that the answer is supposed to be received within some time boundary.
It depends on the way you interconnect between the services. The easiest approach is to spawn an http request from the aggregator service to the service that actually bring the data.
This http request can be set in a way that it won’t wait longer than X seconds for response. So you spawn multiple http requests to different services simultaneously and wait for response. I come from the java world, where these settings can be set at the level of http client making those connections, I’m sure node ecosystem has something similar…
If you prefer an asynchronous style of communication between the services, the situation is somewhat more complicated. In this case you can design some kind of ‘transactionId’ in the message protocol. So the requests from the aggregator service might include such a ‘transactionId’ (UUID might work) and “demand” that the answer will include just the same transactionId. Now the sends when sent the messages should wait for the response for the certain amount of time and then “quit waiting” after X seconds/milliseconds. All the responses that might come after that time will be discarded because no one is expected to handle them at the aggregator side.
BTW this “aggregator” approach also good / simple from the front end approach because it doesn’t have to deal with many requests to the backend as in the gateway approach, but only with one request. So I completely agree that the aggregator approach is better here.
I have the current APIs running in an express server along with MongoDB in form of HTTP requests response. I currently have the use case of a messaging system that I know requires web sockets.
Should I rewrite the whole APIs in socket.io? Or Is there any option to do it on top of the existing HTTP server
Any suggestions in this situation will be helpful.
No, the are not mutually exclusive. Keep using HTTP for things that make sense as APIs, and only add sockets for the things that require bi-directional messaging.
socket.io is not required, and it's usually better to just use plain websockets. socket.io is a old, large framework that's not needed.
These days I try to develop real time application using nodejs.
That application want to update the dashboard according to api data.
I installed express and faye and try to compare what is the best and what are the differences of that two.
As I know express is a node base framework and faye is a subscriber/publisher based one.
But I think both are almost same and anyone can help me to identify the differences?
What is fast and what can be done using the frameworks like that ?
Thanks in advance.
They are not very comparable. If you want to create a real-time application, you will probably need to use both.
Express is a web framework. You will need it to serve and handle HTTP requests and responses. It will help you handle things like url routing, request/response handling middleware, interfacing with template engines, etc... Express is as fast as you'll get.
Faye is a pub sub messaging system- It will not be capable of handling standard HTTP requests and responses. You may be able to implement a live stream of the data using Faye, however, you will still have the need to serve up your client side application using Express.
I would also look into Socket.io as an alternative to Faye- in addition to Express.
Most examples I have seen are are just small demo's and not full stack applications and they use websocket for messaging, but for any chat application there is more data then just messages...suppose like user profile, his contacts etc.
So should I use websockets for all communication between server and client or just use them for sending messages and do other things through http? If I am to use websocket for all communication how do url design of the app...since websockets don't have have any different urls like http.
You might be interested in WAMP, an officially registered WebSocket subprotocol that provides applications with WebSocket based
asynchronous, bidirectional remote procedure calls
real-time publish & subscribe notifications
Disclaimer: I am original author of WAMP and work for Tavendo.
Pretty sure you'll get the usual "it depends" answer, because, well, it depends!
If you are going to build a large application, to be used by a number of different clients in different network arrangements etc then I personally wouldn't recommend using WebSockets for everything. Why?
It's a new standard, so not all clients support it
In some network configurations WebSocket traffic may be filtered out, meaning you end up with no communications - not great
If you end up exposing an external API then HTTP is much better fitted for the job and will likely be easier to code against. There are a lot more tools out there to help you with it and styles that everyone is familiar with, like REST, to follow.
Use WebSockets when you require data being pushed from the server without the client having to poll for it, or when HTTP header overhead becomes a problem. And if you still decide to use it make sure you have a fallback mechanism (e.g. longpolling) so you don't end up with no comms.
I'm afraid I can't help you regarding WebSocket API design... given it's a new standard I don't believe the community has settled on anything just yet so you'll have to come out with your own message-based scheme.
I'm working on an application that relies on data that the browser sends within the HTTP headers (and there's no way around this). This also happens to be my first time working with something node.js based, so it's very likely I'm completely missing something simple!
Basically what I want to be able to do is call a method on the server from the client, and in that method read the HTTP headers that the client sent.
Meteor doesn't yet provide a supported API for serving HTTP from your app. This is intentional: in the not-too-distant future, your app server is likely to not be just a single process directly serving end users, but an arbitrarily parallelizable service behind a proxy tier. So we'll need to provide a supported API for responded to HTTP requests (REST, eg) that continues to work in such a setting.
Are you sure it needs to be HTTP and that you can't just use a Meteor method?
If you really need to accept direct HTTP requests now, take a peek at how packages/accounts-oauth-helper/oauth_server.js uses __meteor_bootstrap__.app to hook into the Connect middleware framework. This will work for now, but we don't promise that Meteor will always be powered by Connect :)