The easiest way to demonstrate this is to create a simple LightSwitch application, attach to a database with data, create a simple screen, and then “launch” our app. We can then use Internet Explorer’s F12 Debugging Tools to look at the size of the HTTP requests and response.I’m going to walk through making a simple LightSwitch project. If you aren’t familiar with making a LightSwitch project, please check out the very short tutorial on our Developer Center
Launch Visual Studio and navigate to File –> Create New Project and select a LightSwitch HTML Application (theLightSwitch Desktop Application uses a Silverlight Client, which has actually already been using the JSON Light format since Visual Studio 2012 Update 2).
After you’ve done this, go ahead and click “Attach to External Database”. Lets attach to some database that already has data in it (I’m attaching to a Northwind SQL Database, but if you don’t have that available, you can attach to the Northwind ODATA Service). Select which tables you want to import and click “Finish”.
We need some way to display the data, so let’s make a very simple screen around one of our database tables.
Right click on the LightSwith HTML Project, and select “Add Screen…”
Select the “Browse Data Screen” template, and for the Screen Data just select some table that you know has data (I’m using a Customers table).
Now we can launch our app and use Internet Explorer’s F12 Developer Tools to look at a particular HTTP request.
Press F5 to launch the LightSwitch HTML app
When IE launches, press F12 to open the Developer Tools
Select the “Network” tab and then click the “Start Capturing” button. This will start “recording” all HTTP traffic.
Now “refresh” your browser. You should see a bunch of HTTP requests appearing. After the browser finishes refreshing, select the last HTTP request in the list (it should be last or close to last). It will look something like this:
/DBData.svc/MyCustomers?$top=45 GET 200 application/json 12.60 KB 0.56
I chose this request because it is the actual request to retrieve data from the Server and pull it back to the Client. So this request, and any HTTP GET/READ request like this, are the ones where we will see the HTML Client using the new JSON Light format
In English, what this request shows, is that I requested the first 45 records from my entity, and that the response came back in a JSON format. But most important, the response size was 12.60KB and it took 0.56 seconds.
To be sure that we are using the JSON Light format, we can drill down into this a little more. Just double click on the request, select the Response Headers tab, and look at the Content-Type header.
What this shows is that our HTTP response was returned in a JSON format called “minimalmetadata” (another name for JSON Light).
(The F12 Developer Tools are pretty powerful, definitely encourage you to read up more on it if you like - IE F12 Developer Tools).