i am taking a course in web data so i understand that when we want to retrive a webpage on a browser we do a request response cycle using a communication protocol like http or https and a web service is a piece of software which i dont know where it is stored or how it is accessed so we can make two applications from different architectures communicate using a serialization language like XML or JSON i dont know what is the difference between a web service and http they are both a way to connect 2 different computers together and what confused me the more is api which according to the research i did is something used to access web services.
Let's begin with defining all the terms in your question since it's a bit all over the place.
HTTP (Hypertext-Transport Protocol): Allows you to transfer data over the web. Your browser will perform a request using HTTP to your web service.
Service: Any software that performs a specific task. We are interested in a web service, which is typically invoked via HTTP, however this can be anything else such as a Linux signal.
For now, let's assume it listens on HTTP.
API (Application Programming Interface): An interface by which all clients of your software have to abide by to use it. For example, in our web service, we can dictate an API so requests follow some convention.
Let's put it all together now.
You're making a website that wants to calculate the sum of two numbers. First, users will go to http://yoursite.com, and then the browser will always do an HTTP request to the domain yoursite.com on port 80. This will hit either your hosting site or some backend server.
Here you have the option if you're using something like GitHub pages to serve static content or you have some server (i.e., serverd) that will load a file and serve it.
So now the web-browser did an HTTP request and your webpage should load with an index.html. The user can now click on buttons, and everything looks good until they press Calculate -- what happens now?
We want to offload the computation to our backend. We perform an HTTP request to our backend server. We can define an API, that is in our case an endpoint, so that the HTTP request can hit it and it'll return the sum of the two numbers.
How do we return the result? We need to represent the data somehow, and this can be done through a body payload that is encoded as either JSON or XML. Again, this is a serialization format and can encode it in various different ways. JSON is nice because you can parse it easily with JavaScript on the client side.
Great -- so now we got an entire site and it works! Now we can do an HTTP request from our browser straight to the backend according to our setup endpoint and it should fulfill our request. Notice how now we're using the API from the backend server from within our site.
Other keywords you can may run into: CORS, AJAX, Apache Server; good luck!
Related
From what I've gathered, hosting a website on a server is allocating space for the files of your website whereas hosting an API is when the server continuously runs your API to receieve incoming web requests. Is it true that when hosting a website, the server is not running anything? Or is it also continuously running the website waiting for calls.
When you request a website, it makes a call through the network to a server machine that runs an application called a web server, for example Apache HTTP Server. Without that application, it would be unable to respond to your HTTP calls with web pages.
Web pages are just documents and resources, so they are not able to respond by themselves. An API, on the other hand, is usually a separate standalone application that can run on a different machine, and that is often called by web pages.
So the answer is no: the server has to run something even for a static website.
You need a server to "serve" your web-page. It does not matter if is a static page or a dynamic page (html or php). If you have a html page the server will read and sent it to the user(No processing done), if you have a dynamic page like php then the server will process the php code and generate a result usually an HTML page that its serve to the client.
If you have an API is the same approach as the dynamic page, you send parameters, server process them and then give you a result. In the case of an API it may require authentication and the result can be in HTML, XML, JSON for example.
I've been doing a ton of research on Microservices however I cannot find a single piece of code that is written for an API gateway. I understand that between the clients and services you would have an the API Gateway which allows a client to make 1 requests over IoT to the gateway and then the gateway can make many requests internally to services which then build up a response. Now from an article on NGINX
The API Gateway is responsible for request routing, composition, and protocol translation.
use case
Suppose we support 2 clients. Android and an Angular App (browser) and let's make a tangible user story that the client is an online shopping store.
the shopping store would then have different services broken out into servers and each service could be built on a different platform/language with a different database. They are completely self contained so that they can scale in the cloud really quickly without having to scale the entire application. If there is some intense Algorithm that needs to run for payment. Then the payment services can quickly spin up a few more servers to balance the load and decrease user wait time.
but that could be written in Java which could have a HTTP/REST exposed api to be consumed. However what if it's written in say c++/Golang/Node it doesn't really matter what language, but instead of exposing their api via HTTP it's by a different protocol what would that mean on the api gateway - how would it handle the response?
the client goes and makes a request to the home page where we have 3 things loaded
shopping cart
list view of shoppings items
current specials
the client would only make 1 request to the api gateway let's say to apigateway/apiv1/home to the api gateway which then would have 3 requests to the services so
serviceShopping/apiv1/shoppingList
serviceCart/apiv1/cart
serviceSpecial/apiv1/specials
at this point the 3 services could be written in a different language and use a different protocol. How would those 3 services be requested and on the response back to the client (a single response) how would it be concatenated? json object with a specific schema? this is where I get confused...
sorry for the long post it's a simple question I think, but I needed to setup something I can conceptualize with and explain.
I have a MarkLogic-based web application which pulls data from two sources, a document store and a triple store both hosted on my MarkLogic server. The app uses MarkLogic's built-in REST APIs to access these data stores. The document store's REST API is running on port 8003 and the triple store's REST API is on port 8007. The application is hosted on the modules database of the document store. Now, when I make a REST API call to pull triple data, I get an exception saying the 'access-control-allow-origin' header has not been set at the server side. I would like to know how I can set it up so I get 'access-control-allow-origin' as '*' in all responses from the REST API. I have read the documentation on xdmp:add-response-headers, but I'm not able to figure out where I can use it correctly. All help is much appreciated!
Thanks!
Why not keep the documents and triples in the same database? The ability to do that is one of MarkLogic's strengths.
The built-in REST API endpoints don't seem to support any mechanism for adding arbitrary response headers. However you should be able to add your own headers when writing a REST extension: https://docs.marklogic.com/guide/rest-dev/extensions
For the built-in endpoints you might consider routing requests through another app-server layer, or a transparent reverse proxy. Either way the goal would be to re-route requests so that the browser thinks both REST API instances are on the same server.
I have a service that always returns the same results for a given parameter. So naturally I would like to cache those results on the client.
Is there a way to introduce caching and other effect inside the WCF pipeline? Perhaps a custom binding class that could site between the client and the actual HTTP binding.
EDIT:
Just to be clear, I'm not talking about HTTP caching. The endpoint may not necessarily be HTTP and I am looking at far more effects than just caching. For example, one effect I need is to prevent multiple calls with the same parameters.
The WCF service can use Cache-Control directives in the HTTP header to say the client how it should use the client side cache. There are many options, which are the part of HTTP protocol. So you can for example define how long the client can just get the data from the local cache instead of making requests to the server. All clients implemented HTTP, like all web browsers, will follow the instructions. If your client use ajax requests to the WCF server, then the corresponding ajax call just return the data from the local cache.
Moreover one can implement many interesting caching scenarios. For example if one set "Cache-Control" to "max-age=0" (see here an example), then the client will always make revalidation of the cache by the server. Typically the server send so named "ETag" in the header together with the data. The "ETag" represent the MD5 hash or any other free information which will be changed if the data are changed. The client send automatically the "ETag", received previously from the server, together inside the header of the GET request to the server. The server can answer with the special response HTTP/1.1 304 Not Modified (instead of the typical HTTP/1.1 200 OK response) and with the body having no data. In the case the client will safe to get the data from the local cache.
I use "Cache-Control:max-age=0" additionally with Cache-Control: private which switch off caching the data on the proxy and declare that the data could be cached, but not shared with another users.
If you want read more about caching control with respect of HTTP headers I'll recommend you to read the following Caching Tutorial.
UPDATED: If you want implement some general purpouse caching you can use Microsoft Enterprise Library which contains Caching Application Block. The Microsoft Enterprise Library are published on the CodePlex with the source code. As an alternative in .NET 4.0 you can use System.Runtime.Caching. It can be used not only in ASP.NET (see here)
I continue recommend you to use HTTP binding with HTTP caching if it only possible in your environment. In the way you could save many time of development and receive at the end more simple, scalable and effective application. Because HTTP is so important, one implemened already so much useful things which you can use out-of-the-box. Caching is oly one from the features.
The question is as simple as the title. I have a webapp (I have no clue as to what technology it was built on or what appserver it is running on). However, I do know that this webapp is being served by an Apache Server/ IIS Server / IBM Http Server. Now, I would like to have a plugin/ module / add-on at the web-server end, which would parse/truncate/cut/regex the http response (based on the requested url's pattern), and mask(encrypt/shuffle/substitute) a set of fields in this response based on different parameters(user's LDAP permissions in the intranet / user's geo-location if on the internet, etc) and send the altered response back to the user.
So, Is there an easy answer to creating such plugins/modules/add-ons? How feasible is this approach of creating extra software at the webserver, when you want to mask sensitive information in a webapp without modfying the web-app code? Are there any tools that help you do this for Apache?
And, finally, is this just a really crazy thing to try?!
Each webserver will have its own way of doing so.
There is no universal plugin architecture for webservers.
In IIS you would write an HTTP Handler or HTTP Module, or possibly an ISAPI Filter. You can also directly interact with the http response using the Response object exposed by the HttpContext.
With apache, there are different modules that can do what you want (mod_headers, for example).
I don't know anything about WebSphere, but I am certain it also has similar mechanisms.
What you are asking is required by most web applications, so would be either built in or very easy to do.
The easiest way is to add a plug-in using the web application container. For example, if it's Tomcat, you can add a filter or valve.
If you want to plug-in to the web server, you'd need to write a custom module using the API of whichever web server is being used.
If all else fails, you could always wrap the entire server in a reverse proxy. All requests would go through your proxy and that would give you the opportunity to modify the requests and the responses.