# C# wrapper demo callback

**URL:** <https://devforum.zoom.us/t/c-wrapper-demo-callback/25284>\
**Category:** Windows\
**Created:** [July 27, 2020, 5:24am UTC](https://devforum.zoom.us/t/c-wrapper-demo-callback/25284 "2020-07-27T05:24:54Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![carson.zoom](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/carson.zoom/32/785_2.png) [@carson.zoom](https://devforum.zoom.us/u/carson.zoom)\
**Post date:** [July 29, 2020, 5:37am UTC](https://devforum.zoom.us/t/c-wrapper-demo-callback/25284/3 "2020-07-29T05:37:32Z")

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Hi @saurabhbharadwaj,

Thanks for using Zoom SDK. If you are trying to run the demo app in the C# wrapper, here are the steps:

- Download the C# wrapper and navigate to `zoom_sdk_demo`, click on `zoom_sdk_demo.csproj` to launch the project
- Set the Solution Configuration to be “Release” and Solution Platform to be “x86”, then build the app
- In the Auth page, use the following template to compose your payload for SDK initialization:

\*\* Header

```auto
{
  "alg": "HS256",
  "typ": "JWT"
}

```

\*\* Payload

```auto
{
	  "appKey": "string", // Your SDK key
         "iat": long, // access token issue timestamp
         "exp": long, // access token expire timestamp
         "tokenExp": long // token expire timestamp, MIN:30 minutes
}

```

**The minimum value of `tokenExp` should be at least 30 minutes, and `exp` should be later than `tokenExp`, otherwise, SDK will reject the authentication request.**  
\*\* Signature

```auto
HMACSHA256(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload),
  "Your SDK secret here"
)

```

I have just tried the above steps with the demo app and the callbacks could be triggered. Please have a try.

Thanks!

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