Never expire Salesforce session - asp.net

Question

I am integration Salesforce OAuth in my application. After mapping users' Salesforce account with our application account I saved access token in DB. When user make request to fetch data from his Salesforce account I just use that token to get data. Sadly, token has expiration time (max 24 hrs). After token is expired user has to again connect salesforce account with our app.
Is there anyway to keep salesforce session alive for unlimited time or any other way to avoid repeated login?

Answer 1

I think what you are looking for is a Refresh Token process. Although you can control the expiration time, as you said there is certain limits you can't pass. Instead you can send a request to your org that can obtain new Session ID for you.
Example:
POST /services/oauth2/token HTTP/1.1
Host: https://login.salesforce.com/
grant_type=refresh_token&client_id=3MVG9lKcPoNINVBIPJjdw1J9LLM82HnFVVX19KY1uA5mu0
QqEWhqKpoW3svG3XHrXDiCQjK1mdgAvhCscA9GE&client_secret=1955279925675241571
&refresh_token=***your token here***
Note that this does not work if you are using username-password OAuth authentication flow. Check this dev documentation for the parameters you can use for Refresh Tokens and what responses can it return. - https://developer.salesforce.com/docs/atlas.en-us.api_rest.meta/api_rest/intro_understanding_refresh_token_oauth.htm

Answer 2

It is not possible to make sure that user session never expires. However, you can setup the session timeout value to a maximum of 24 hours.

Answer 3

I agree with Iojo. I implemented the similar requirement to save the Token in DB and reused it for multiple API callouts.
Note: In my case - for all the API callouts - Authentication layer are taken care by same middleware. Additionally, I am using username-password for access token where, clearly, I cannot use refresh token.
What I did for Access Token with token
saved in DB?
//Please create a re-usable method in the Rest handler to Retrieve Token
private string getToken(){
If(Token created within Session Timeout Limit){
//Use encrypted token given in the DB
}
else{
//reuse code to generate new token
//save the encrypted token in the DB for future use
}
}
Benefits:
You need to generate Token just one time within given Session Timeout Limit
Re-use the same if there are multiple API calls in salesforce