# Need some guidance for an app development

**URL:** <https://discourse.sst.dev/t/need-some-guidance-for-an-app-development/2421>\
**Category:** General\
**Created:** [July 8, 2021, 3:23am UTC](https://discourse.sst.dev/t/need-some-guidance-for-an-app-development/2421 "2021-07-08T03:23:57Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![underscore-ex](https://yyz2.discourse-cdn.com/flex032/user_avatar/discourse.sst.dev/underscore-ex/32/485_2.png) [@underscore-ex](https://discourse.sst.dev/u/underscore-ex)\
**Post date:** [July 8, 2021, 3:23am UTC](https://discourse.sst.dev/t/need-some-guidance-for-an-app-development/2421/1 "2021-07-08T03:23:57Z")

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I have an app idea which i am trying to build. The app is more or less like a forum but it has some custom use-cases. I have decided to implement the backend using aws serverless but there are couple of things which are confusing me.

1. I am planning to start app development with api gateway. Is it possible to add appsync layer later on once the backend is built using api-gateway?

2. One of the use case that i have is to add more information during signup. I will be using cognito to do the signup and post-signup lambda to persist the addtional details in dynamodb. Can this lambda be created using serverless stack (it wouldn’t have any rest api end point)

3. I’d need to build some dynamo triggers to trigger a lambda (so that it can update new posts for a user). Can this lambda be created using serverless stack and so on?

Thanks

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<div class="post-metadata">

**Author:** ![rcoundon](https://yyz2.discourse-cdn.com/flex032/user_avatar/discourse.sst.dev/rcoundon/32/991_2.png) [@rcoundon](https://discourse.sst.dev/u/rcoundon)\
**Post date:** [July 14, 2021, 6:24pm UTC](https://discourse.sst.dev/t/need-some-guidance-for-an-app-development/2421/2 "2021-07-14T18:24:47Z")

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I’m not sure about 1.

2 - You can do this with CDK which is possible within an SST stack. I don’t believe there’s a construct for Cognito in SST just yet  
3 - You’d add a lambda to consume a DynamoDB stream - some info [here](https://docs.serverless-stack.com/constructs/Table#enabling-dynamodb-streams)

Hope that helps