I am currently consuming OData in a Xamarin App - and there is a significant performance issue on devices older than the iPhone 5. I believe it is because a simple request returns a significant amount of Xml - which has to be parsed by the phone.
Using Json cuts the payload size to 1/10th.
(note: I am referring to the fact it will reduce the amount of work that the client library has to do, not the fact it will transfer over the network more quickly)
How can I turn on Json in Simple.OData? Xml is basically unusable on iPhone 4.
Thanks
JSON support has been added to Simple.OData.Client 4.0. It should work fine now.
According to OData Protocol, add the following in http header will enable server using Json format:
Accept:application/json
Or add the $format in url like following:
BaseUrl\Customers?$format=application/json
Related
I have a RestFul server that is suppuse to return a large json object more specifically an array of objects to browsers. For example 30,000 points will have a size of 6.5mb.
But I get this content mismatch error in browser when speed is slow. I feel it is because large data throught rest api breaks up something. Even in Postman sometimes it fails to render even though i see data of 6.5 mb received.
My Server is in NodeJS. and return content-type header is application/json.
My Question is
Would it make more sense if I return a .json file. Will the browser be able to handle. If yes, then I will download the file and make front end changes.
Old URL - http://my-rest-server/data
Proposed Url - http://my-rest-server/data.json
What would be content-type in the proposed url?
Your client can't possibly expect to want all of the data at once but still, want their data fast data.
...but you might want to look into sending data in chunks and streams:
https://medium.freecodecamp.org/node-js-streams-everything-you-need-to-know-c9141306be93
When I'm checking web requests in Chrome's DevTools on Mac (Network tab), I've got the Payload in the following format:
7|0|6|https://www.example.com/app/Basic/|00D1D071AC218DFE91521C012683E911|com.optionfair.client.common.services.nongenerated.RefreshService|getCometUpdates|I|J|1|2|3|4|3|5|6|6|173|VvAwAqy|o$UN|
which is basically separated by vertical bar character (|).
How I can copy or convert above payload from Chrome into some meaningful format such as JSON? Any ideas?
Btw. In this question it looks fine on the screenshot, but in my case, I don't have view parsed and it doesn't look like JSON format at all.
Using Google Chrome on Mac (Version 57.0.2987.133, 64-bit).
Reproducible steps:
Go to this page.
Open DevTools on Network/XHR tab and look for refresh requests.
My goal is to reuse/replicate the POST data in Request Payload in the command-line tool such as curl so it can be recognized (not necessary on the page mentioned above, but I'd like to know the general approach to deal with this blob format). I would expect JSON format, but it's not.
Here you need to look at the request header content-type to determine how this request was encoded before knowing what might parse it:
This is GWT RPC, so it can include serializations of built-in and custom Java Objects, where knowledge of the class is in both server-side Java and transpiled Java running on the client via Google Web Toolkit.
There is no reason for Chrome to understand this format directly, and it need not have a JSON or XML cannonicalization. Fully interpreting these calls to the extent it is possible on the client may require disassembly or introspection tricks against the transpiled client code, assuming the program wasn't transpiled with source maps.
Without digging into the client code, one can interpret the literal rpc while guessing at or probing the definition of classes and their methods by modifying the call.
I'm writing a RESTful web application where I need to provide the service of uploading images for a user. Currently, I have been able to upload an image from my current machine but I need to send it as JSON data over the web through the REST protocol.
In the server, there is a Java application running Jax-RS to manage the RESTful service. I was planning to save the JSON data that contains the image in the server and then provide a URL to the user for him to be able to locate it's image on the server.
Can someone provide some ideas on how can I do this?
If you want to send the image in a JSON object, then the image should be Base64 encoded it, or some other form of encoding. Then on the server side you will need to unmarshal the JSON and then decode back the image. You can get some ideas here on how that can be done.
Optionally, instead of doing all the converting inside the resource method (as in the example linked above), you could write a custom MessageBodyReader, where you can do the unmarshalling and decoding there.
If you decide you don't want to work with JSON, you can go the normal route and use Multipart. Depending on the implementation of JAX-RS you are using, multipart support will be different. You can see some examples (all examples have links to the official documentation)
Jersey example
Resteasy example
CXF example
There are other implementations, but I don't have examples for those. You will need to search for the documentation if you're using an implementation other than listed above.
I am working on a mobile app. Since I wanted a solution that would work on multiple platforms, I started with Cordova. As I have much data to handle and many views, I decided to use Ember.
I need to use three different JSON datasets that are updated rather frequently in the database. To enable the mobile app to work offline, I will have to store the JSON data, as well as update them when the database is changed.
Questions
How can I retrieve JSON from another server(CORS blocked)?
How can the retrieved JSON be saved on device? [HTML5 LocalStorage(preferred) or FileAPI]
How to read JSON file and send data as model to templates? (I guess Ember.$.getJSON can do this)
Any help is welcome. Thanks!
Update 1
Since I ran into many issues using Ember-data, I am not using it in my app.
Found this link for cross-domain with ajax
Update 2
CORS can be solved only by JSONP or by setting ACCESS-CONTROL-ALLOW-ORIGIN in the reponse of the server(I tried many other solutions, and failed)
Since the api is in my server, I did the latter.
For 2 and 3, I think I could use this SO question
This is what I found out :
JSON data from a server in different domain
You cannot read JSON data from a server in another domain. This is due to the Same-origin policy implemented in browsers. A browser will retrieve your JSON but will not allow you access to the same. There are two solutions(AFAIK) to this problem :
Using JSONP - I'm not going into the details, but there are many links available for this.
Allow CORS from server - When the server sends JSONified data, you can add additional headers for ACCESS-CONTROL-ALLOW-ORIGIN. After retrieving the JSON from server, the browser checks for this header to either block or allow CORS. I used some decorators for adding crossdomain headers and then my data was successfully read in the browser.
Saving the json data
HTML5 makes everything easier. In your javascript, you just have to use :
localStorage["application.state.data"] = JSON.stringify(json);
or
localStorage.setItem("application.state.data", JSON.stringify(json));
Retrieve works just the same
var data = JSON.parse(localStorage["application.state.data"]);
or
var data = JSON.parse(localStorage.getItem("application.state.data"));
I'm want to try changing a SOAP WCF to accept requests and return results in JSON format to make the data traffic less bulky.
I see that JSON requests functions looks like this:
wcfClient.OpenReadAsync(http://yourUrl.com/wcf/service1.svc/GetEmployees)
and do the regular SOAP requests functions instead that looks like :
wcfClient.GetEmployeesAsync();
1) For JSON results, do you need to parse them into an object or is it automatically parsed like SOAP?
2) Is there a way to do this without doing too much work like changing every single WCF calls in the project to looks "JSON-ish"?
To complement Davut's answer - WCF does support building RESTful services, although I agree that the ASP.NET Web API framework in general easier to use than WCF. JSON.NET is a great library, and it has nice deserialization capabilities (e.g., it can easily take the JSON which represent the list of Employee objects and convert them into the actual List<Employee> instance)
But for completeness sake, if you want to use a "normal" WCF client to access WCF-based services which return JSON, you can do it. It's not too straightforward, but you can do that by using a new encoder and behavior which does the conversion. The post at http://blogs.msdn.com/b/carlosfigueira/archive/2010/04/29/consuming-rest-json-services-in-silverlight-4.aspx talks more about it, and has a pointer to a code sample.
In short, it's possible to consume JSON using a WCF client in Silverlight, but due to its complexity it's usually not done, and Davut's option (use a HTTP client such as WebClient to download JSON, then a library such as JSON.NET to parse it into objects) is preferred.
Firstly the idea "make the data traffic less bulky." is good.
Especially for Mobile devices. Beside this don't think that WCF xml causes network issues for PC. XM is the one of most compressible format. By WCF binary it goes as compressed.
For "Is there a way to do this without doing too much work?"
Yes there is a way name on it RESTFul Services(Restless Services). Now Microsoft directly support it by WEBApi.
Also you may use ODATA for filtering,ordering operations
Here are some links,
http://msdn.microsoft.com/en-us/library/system.servicemodel.web.webgetattribute.aspx
http://blogs.msdn.com/b/rjacobs/archive/2010/06/14/how-to-do-api-key-verification-for-rest-services-in-net-4.aspx
ODATA
http://www.odata.org/documentation/uri-conventions#FilterSystemQueryOption
A few practice notes,Some restrictions:
EntityFrameWork entities derived from EntityObject which has IsReferenceType attribute doesn't allow you to JSON serialize. ( I produced POCO objects using an automapper mapped them and serialized json)
WEBAPI support you much think such as WebGet,WebInvoke GetXML Give JSON ,ODATA features(just select and format not allowed.)
Note:In your web request's header you should accept text/json to get really json.
"For JSON results, do you need to parse them into an object or..."
I can say you should try JSON.NET it's portable library works everywhere. When you deserialize with a generic function it returns you the collection you expect.
Hope it helps someone. While discovering these stackoverflow helped me like an assistant.