i am quite noobie about OpenStack components and role, and i am having trouble understanding how each component works and when they operate;
Suppose that i have a certain image in my openStack storage and a client uses it and complete some operation(like saving files); how is the interaction between the components to perform this operation?( i would like to know how and which conponents work from the creation of volumes to the changements saved;
Thank you very much.
Openstack follows Service Oriented Architecture. It uses WSGI and django framework. So, every component exposes few REST APIs.
You can find these APIs in api folder. For example (https://github.com/openstack/cinder/tree/master/cinder/api).
Internally, these API calls make call to manager. manager.py is the file which handles main logic. (https://github.com/openstack/cinder/blob/master/cinder/volume/manager.py).
It calls underlying driver classes and co-ordinate with other openstack services through their APIs.
Related
My goal is to implement a generically extendible .NET core web API. The generic refers to modules that can be added at runtime and provide new endpoints as well as functionality. These modules will be developed based on a framework.
Currently I am still deciding if the modules will be included as a DLL or run as a separate process (.exe).
I have the basic understanding of Dependenci Injection regarding the addressing of controllers in a DLL. But now I wonder if and how to realize the whole thing via an own process.
The API should always be addressable via http://localhost/myapi/{endpoint}, i.e. a request to a module should be done via the same URL. For the user / developer of the frontend everything should be presented as one API.
Unfortunately I was not successful on my research and don't know exactly what I have to / should look for specifically. Therefore I hope that you can help me.
Examples are helpful, but I am also keywords or articles, which deal with such a topic, help me further.
kind regards
I have a project for Master's Degree: design and implementation of web services for an elearning platform.
Now, I know that there are two main architectures for web services: SOAP, and REST
Now, I wanted to use REST architecture, so normally I would have something called "RESTful web services", so I started development with Django and Django Rest Framework
Now, this is the part where I get confused, Is this an API or Web Services
If it is an API, then how can I develop RESTful Web Services?
If it is both, please explain more if you could.
I'm very confused about this, and each time I try to understand, I get more confused, Please can someone clarify this to me?
An application programming interface (API) allows you to interact with a component, system, or resource. It's a very broad concept. To understand it, the emphasis should be placed on the word interface:
In computing, an interface is a shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these.
When you need something from a component or you want it to do something for you, you don't just go in it and do it yourself, you "ask it" for that something or for that action by interfacing with it. The interface of the component says what it can do for you or what you can invoke from the component.
In regards to web services, you have to understand that a web service is in fact an API, because it's an interface with some component (in this case whatever is behind the web service itself: it can be a database, an application, a system, etc).
Like I said, an API is a very broad term. When you say web service, you are adding some restrictions to that term. For example, a web service is invoked over the network. Not all APIs are like this. Some API's can be exposed as libraries, or frameworks that you call directly from your code as methods or functions. So all web services are APIs, but not all APIs are web services.
If you want to build a web service, you can implement it with REST or with SOAP. There is a difference between the two (REST is an architectural style, while SOAP is a protocol), but as concepts they work the same: they provide an interface with which to interact over the network, i.e. an API. But since you are using Django, thus Python, I suggest you go the REST way, not SOAP (support for SOAP in Python isn't all that great).
I am currently looking at implementing feature toggles using ff4j for our application. We want to have a remote central config app which will hold all the features in it and the applications will talk to this central config app via REST to get the features. We will not be able to leverage Spring Cloud Config or Archaius for this purpose.
I went through the documentation and it seems there is a support for HttpClient (https://github.com/ff4j/ff4j/wiki/Store-Technologies#httpclient). But I couldn't find any sample for the same. Can someone please let me know if I can leverage this method to build my feature store from a REST endpoint. Also, I would appreciate if someone could point me to a sample of this.
This is a common pattern.
A component holds the Administration UI (console) and the REST API. You can call it the "Admin Component". For security reasons It may be the only component to have access to persistance unit (any of the 15 DB implementation available)
For the "admin component" HERE is sample using standAlone spring-bppt application using JDBC DB, and HERE you find a simple web application.
The REST API can be secured using credentials user/password and/or API Key. More information HERE
All microservices access the REST API as clients and request feature store. You will need the dependency ff4j-webapi-jersey2x or ff4j-webapi-jersey1x that hold the client http> Then you can define the store using :
FeatureStoreHttp storeHTT = new FeatureStoreHttp("http://localhost:9998/ff4j");
Warning : Please consider using cache to limit overhead introduce by accessing the REST API at each feature usage. More info on cache HERE
I create my API rest with Django, but I don't understand how convert an API to micro services, I don't understand the real difference between these.
I see an API like a micro service, but I don't know convert an entire API in micro service, I need create micro web servers?
Please, I can't understand a micro services, and I need understand this.
A microservice exposes it's interface, what it can do, by means of an API. The API is the list of all endpoints that a microservice respond when it receives a command/query. The microservice contains the API and other internal+hidden things that it uses to respond to client's requests.
An API is all that the clients see when they look at the microservice, although the microservice is bigger than that. A microservice hides its internal structure, it's technology stack, it's database type (sql, nosql - it could be anything); a microservice could move from sql to nosql, from python to php, but keep it's API unchanged.
API - It a way of exposing functionality over web. Imagine you have developed some functionality in .Net but not you are developing some software in a different language. Would you develop the same functionality again? No. So, just expose it via web service.Web services are not tied to any one operating system or programming language. For example, an application developed in Java can communicate with the one developed in C#, Android, etc., and vice versa.
Microservice - They are used to break a complex software into small pieces of individually deployable, testable, loosely coupled sub-modules. Micro Services are designed to cope with failure and breakdowns of large applications. Since multiple unique services are communicating together, it may happen that a particular service fails, but the overall larger applications remain unaffected by the failure of a single module.
API Vs Microservice - Now that we have broken our complex software into loosely couple sub-modules. These sub-modules communicate with each other via an API. Therefore, Microservices and an API solve different problems but works together!
More Details:
The Difference between Web Services and Micro Services
RESTful API vs Microservice
a microservice is an autonomous RESTful service. It means, there is just one service on each server. In Spring Boot when you bootstrap your RESTful service, it will get an instance of tomcat(it's embedded tomcat) and run your service on it. So, if you have more than one service on a server, it is not a microservice, because these services are not autonomous.
I need to write a Java web application to call a function Meteor APP. One way is through API call. Are there any other means to call Meteor function from 3rd party application.
Thanks
Murali
It all depends on what your requirements are, how your Meteor app is structured, and what sort of integration you desire.
If you are wanting your Java web application to be able to natively call Meteor methods or subscribe to publications, then you will have to use a Java DDP Client to do this. Fortunately, there is at least one documented Java DDP client that you can use for this (and probably many others out there is you search). For your reference, here is a compiled list of DDP clients for other languages/technologies.
If on the other hand you don't want to interface with you meteor app using DDP, then you could always implement a REST API in your meteor app. There are several packages available to do this, but I would highly recommend the simple:rest package.
This package automatically creates a REST API for all your existing publications and methods without any extra code (just simply add the package to your meteor app). If you do need to configure or modify the REST API, the package also provides several options that you can use in your publication or meteor method definition. The package also enforces all your app's security rules and authorization.
For example, if your app had a publication called openTasks, then the corresponding REST endpoint would be.
GET /publications/openTasks
There are quite a few packages at https://atmospherejs.com/?q=rest that can expose your Meteor methods as RESTful API points which your Java app can consume.