Protocol: A standard to define a method of exchanging data over a network.
If a browser wants to communicate with a server, it has to create an HTTP request and send that HTTP request to the server to convey its request of resources and options. The server receives the request and process it and do the needful and create an HTTP response to send to the browser. The browser has to follow the HTTP specification in creating the HTTP request. The server also has to follow the HTTP specification in creating the HTTP response. This is how the communication between the browser and the server happens in a standard way to avoid conflicts by following the HTTP protocol.
Json Wire Protocol: A client has an object that has to be sent to a server. The client converts this object into a JSON object and sends it to the server. The server parses the JSON object and converts it back to object for use. The server converts the response object into a JSON object and sends it back to the client. The client then converts the JSON object to object for use.
Why the later is called as Json Wire Protocol?
You are pretty correct both about Protocol and JsonWireProtocol. At this point it is worth to mention that, earlier all implementations of WebDriver that communicated with the browser, or a RemoteWebDriver server shall use a common wire protocol. This wire protocol defines a RESTful web service using JSON over HTTP.
JSON Wire Protocol is an abstract specification of how automation behavior like clicking or typing or whatever you actually want to do with your automation script is mapped to selenium or appium or HTTP requests and response. The protocol will assume that the WebDriver API has been "flattened", but there is an expectation that client implementations will take a more Object-Oriented approach, as demonstrated in the existing Java API. The wire protocol is implemented in request/response pairs of "commands" and "responses".
What is JSON Wire protocol?
JSON (JavaScript Object Notation) is a lightweight format for data exchange between client and server. Applications use JSON objects to send and receive data between each other in the web world. JSON data structure is industry standard and can be used for sending and receiving data as Key & Value pair. Some people say its a very nice alternative for XML. We can save JSON files as .json extension.
How JSON looks like?
A simple json file looks like below and there are many online editors which can be used to edit and verify JSON structure.
{
"Student":{
"FirstName":"Pawan",
"LastName":"Garia",
"IdNumber":"12345",
"City" : "New Delhi",
"EmailID" : "email#gmail.com" }
}
Why JSON Wire Protocol was used in first place?
To implement a client-server architecture which can give us the following benefits.
You write test in any programming language.
You can perform or run test on cloud services like SauceLabs, BrowserStack or Selenium Grid setup.
You are not bound to run test only on the local machine.
Different Drivers(FirefoxDriver, ChromeDriver) can be crated for browsers and separate implementation by using the same standards.
So client-server implementation requires a standard set of the specification beforehand so that Server and Client should be in sync with each other in term of what is coming and going on request and response. It’s something like a language of communication with each other. So we need some common specification to solve this kind of requirement and the solution was HTTP.
Why HTTP is the solution?
HTTP is a standard for web and can be a good base for the specification. Every programming language has a good HTTP libraries which can be used for creating client and server for request and response calls.
How JSON Wire protocol worked with HTTP?
HTTP request and response are generally made of GET and POST requests which is out of scope for this discussion.
Current status
From Selenium perspective, JSON Wire Protocol is obsolete now and the WebDriver W3C Living Document is the new implementation.
WebDriver Communication
The WebDriver protocol is organised into commands. Each HTTP request with a method and template defined in the specification represents a single command and hence each command produces a single HTTP response. In response to a command, the remote end will run a series of actions known as remote end steps. These provide the sequences of actions that a remote end takes when it receives a particular command.
Command Processing
The remote end is an HTTP server reading requests from the client and writing responses typically over a TCP socket. In the specification the communication is modeled as the data transmission between a particular local end and remote end with a connection to which the remote end may write bytes and read bytes. The exact details of how this connection works and how it is established is a bigger topic and out of scope for this question. After a connection has been established, the remote end must read bytes from the connection until a complete HTTP request can be constructed from the data. If it is not possible to construct a complete HTTP request, the remote end must either close the connection, return an HTTP response with status code 500, or return an error with error code unknown error.
Outro
Difference between JsonWireProtocol mechanisms and the new standards in W3C Living Document when using Selenium
Related
I'm trying to do few quick prototypes of using RabbitMQ as message broker for internal services as well as messages from external clients received by gateway over websocket connection.
I decided it would be best (and probabaly only) option for client to publish messages as json, and then for gateway to simply send the unaltered json messages forward.
I've seen that RawRabbit have the ability to take raw Json as message and then deserialize it to C# class.
What I can't find is some example and/or documentation of how the process should look like. Also cannot find documentation of how the Json message should be formatted.
When making an AJAX request to a server (may be Java, PHP, etc), is it necessary to pass data as JSON string ?
Can we not pass the object directly ? Are there issues de-serializing OR can that be handled at the backend ? Any examples of handling JS object (if it is possible to send an obj directly) at the backend would be great ?
Object literal makes sense only in the JavaScript runtime environment. Since AJAX body is simply a string, you can pass {a:3} to a server. But what should server side do with it? It ertainly can store it in a database and return to you back when requested. But what if it wanted to extract some data from it? You' have to have JS runtime and evaluate the object using eval. Which would be awkward, but possible. However, not all servers have JS runtime environment. Whereas there are libraries for many languages that support parsing JSON into the representation specific to the language on the server.
An AJAX request passes data to the server in the same way any other HTTP request does. Most commonly, AJAX requests use POST and pass data to the server as POST data, but query strings are often used, and there are other ways to pass data to a server using HTTP and AJAX.
In essence all HTTP data is octets (bytes), and HTTP has no special support for serialization of JavaScript objects, so you or the libraries and/or frameworks you use must handle the serialization.
I got a (Flask) backend powering an API that serves JSON to an Angular app.
I love the fact that my backend (algorithms, database) is totally disconnected from my frontend (design, UI) as it could literally run from two distinct servers. However since the view is entirely generated client side everyone can access the JSON data obviously. Say the application is a simple list of things (the things are stored in a JSON file).
In order to prevent direct access to my database through JSON in the browser console I found these options :
Encrypting the data (weak since the decrypting function will be freely visible in the javascript, but not so easy when dealing with minified files)
Instead of $http.get the whole database then filtering with angular, $http.get many times (as the user is scrolling a list for example) so that it is programmatically harder to crawl
I believe my options are still weak. How could I make it harder for a hacker to crawl the whole database ? Any ideas ?
As I understand this question - the user should be permitted to access all of the data via your UI, but you do not want them to access the API directly. As you have figured out, any data accessed by the client cannot be secured but we can make accessing it a little more of PITA.
One common way of doing this is to check the HTTP referer. When you make a call from the UI the server will be given the page the request is coming from. This is typically used to prevent people creating mashups that use your data without permission. As with all the HTTP request headers, you are relying on the caller to be truthful. This will not protect you from console hacking or someone writing a scraper in some other language. #see CSRF
Another idea is to embed a variable token in the html source that bootstraps your app. You can specify this as an angular constant or a global variable and include it in all of your $http requests. The token itself could be unique for each session or be a encrypted expiration date that only the server can process. However, this method is flawed as well as someone could parse the html source, get the code, and then make a request.
So really, you can make it harder for someone, but it is hardly foolproof.
If users should only be able to access some of the data, you can try something like firebase. It allows you to define rules for who can access what.
Security Considerations When designing web applications, consider
security threats from:
JSON vulnerability XSRF Both server and the client must cooperate in
order to eliminate these threats. Angular comes pre-configured with
strategies that address these issues, but for this to work backend
server cooperation is required.
JSON Vulnerability Protection A JSON vulnerability allows third party
website to turn your JSON resource URL into JSONP request under some
conditions. To counter this your server can prefix all JSON requests
with following string ")]}',\n". Angular will automatically strip the
prefix before processing it as JSON.
For example if your server needs to return:
['one','two'] which is vulnerable to attack, your server can return:
)]}', ['one','two'] Angular will strip the prefix, before processing
the JSON.
Cross Site Request Forgery (XSRF) Protection XSRF is a technique by
which an unauthorized site can gain your user's private data. Angular
provides a mechanism to counter XSRF. When performing XHR requests,
the $http service reads a token from a cookie (by default, XSRF-TOKEN)
and sets it as an HTTP header (X-XSRF-TOKEN). Since only JavaScript
that runs on your domain could read the cookie, your server can be
assured that the XHR came from JavaScript running on your domain. The
header will not be set for cross-domain requests.
To take advantage of this, your server needs to set a token in a
JavaScript readable session cookie called XSRF-TOKEN on the first HTTP
GET request. On subsequent XHR requests the server can verify that the
cookie matches X-XSRF-TOKEN HTTP header, and therefore be sure that
only JavaScript running on your domain could have sent the request.
The token must be unique for each user and must be verifiable by the
server (to prevent the JavaScript from making up its own tokens). We
recommend that the token is a digest of your site's authentication
cookie with a salt for added security.
The name of the headers can be specified using the xsrfHeaderName and
xsrfCookieName properties of either $httpProvider.defaults at
config-time, $http.defaults at run-time, or the per-request config
object.
Please Kindly refer the below link,
https://docs.angularjs.org/api/ng/service/$http
From AngularJS DOCs
JSON Vulnerability Protection
A JSON vulnerability allows third party website to turn your JSON resource URL into JSONP request under some conditions. To counter this your server can prefix all JSON requests with following string ")]}',\n". Angular will automatically strip the prefix before processing it as JSON.
There are other techniques like XSRF protection and Transformations which will further add security to your JSON communications. more on this can be found in AngularJS Docs https://docs.angularjs.org/api/ng/service/$http
You might want to consider using JSON Web Tokens for this. I'm not sure how to implement this in Flask but here is a decent example of how it can be done with a Nodejs backend. This example at least shows how you can implement it in Angularjs.
http://www.kdelemme.com/2014/03/09/authentication-with-angularjs-and-a-node-js-rest-api/
Update: JWT for Flask:
https://github.com/mattupstate/flask-jwt
I was checking the files in the controllers of web module in both OpenERP-7.0 and OpenERP-6.1. Then I found that 6.1 uses jsonrequest (#openerpweb.jsonrequest) 7.0 uses httprequest (#openerpweb.httprequest). What is the difference between the two ?
I didn't look at OpenERP v7 but OpenERP v6.1 uses both - HttpRequest and JsonRequest. I suppose it's the same for OpenERP v7...
Both of them are about communication between client and server. HttpRequest communicates trough the well known GET and POST methods. That means the following:
The client send a request encoded in the url (GET method) or in the http body (POST method)
The server returns an object corresponding to the request. Could be an html page, PNG image, CSS file, JavaScript, XML encoded data or whatever.
JsonRequest is an implementation of another protocol for client/server communication - JSON-RPC 2.0. You may want lo look here for more information. It's a remote procedure call (RPC) protocol which means that it allows the client to initiate the execution of some method on the server passing some arguments to this method. In response the client gets some data as a result of the method invocation.
EDIT - some more words about the decorators #openerpweb.jsonrequest and #openerpweb.httprequest
Some methods are decorated with the #openerpweb.jsonrequest decorator, other methods - with the #openerpweb.httprequest. This means nothing else but that the first group of methods will be available for execution trough the JSON RPC protocol and the second group will be accessible trough the pure HTTP protocol.
Now, what is the difference? And do we need both jsonrequest and httprequest? Let simplify it like this: JSON is more suitable for executing methods on the server and obtain results. HTTP is simpler and easier to use when all we what is to access some resource on the server.
Let's 'decorate' this with some examples for clarity. Take a look at the following method of the web.controllers.main.Export class:
#openerpweb.jsonrequest
def formats(self, req):
""" Returns all valid export formats
:returns: for each export format, a pair of identifier and printable name
:rtype: [(str, str)]
"""
...
This method accepts some arguments and returns a list (Python list object) containing all known export formats. It will be called in a programmatic way in some python code on the client side.
On the other side are the 'http' methods - like the method css() of the web.controllers.main.Web class:
#openerpweb.httprequest
def css(self, req, mods=None):
....
All this method does is to return a CSS file to the client. It's a simple action like accessing an image, a HTML web page or whatever other resource on the server. The resource we are returning here is nothing complicated as a Python list as in the previous example. We don't need a special format to encode it additionally. So we don't need additional data encoding format as JSON and remote procedure call protocol as JSON RPC.
I am developing a web application which communicates to/from a server using JSON. I use
var jsonStr = '{ name: "Rob", time: "2pm" }';
jQuery("#name").jqGrid({
type : "POST",
url:'ControllerServlet?jsonData='+jsonStr,
datatype: "json",
to pass data to server as JSON string, parse it in server, process it and send a JSON back which is displayed in the jqGrid.
This works for me, but I wonder what is the role of JSON-RPC; I read that it is used for remote calls. Is there any advantage in using JSON-RPC instead of using the above way to invoke servlet? How can I use JSON-RPC to do the same action?
As the website states, JSON-RPC is a remote procedure call protocol specification using JSON. It is therefore a specification to call remote methods/procedures on a server similar to XML-RPC or Java's RMI. Both JSON-RPC and XML-RPC can use HTTP as the underlying transport protocol but can also work with others.
On the other hand jqGrid and in general Ajax usually uses HTTP (ideally RESTful) requests to fetch or transfer direct representations of e.g. JSON or XML encoded data. By now this is the preferred way in JavaScript development (comparison of REST vs XML-RPC is a nice read and applies to JSON-RPC as well).