How to use WEB API ? What authentication changes will be require ?

@simples please go through the link. It might be helpful.

forum.appian.com/.../Integrating_Appian-Web_Services.html

Web API needs Basic Authentication. In basic authentication, you need to create a string in this format: "Basic ENCODEDUSERNAME:ENCODEDPASSWORD". The username and password need to be encoded in Base 64. Then pass this authentication in the Header with the key "Authorization" and value equal to the "Basic ENCODEDUSERNAME:ENCODEDPASSWORD"

If you are going to call the web api from Java, you need to follow the above steps sequentially.
If you just want to test it from outside Appian, use a chrome plugin like "Postman". Postman will encode the values for you. Just add a header in the request.

The username and password should be of a Appian user in the environment.

Also make sure that the request method is POST

Hi @chetan, Thanks for your response. I tried to call my web API through 'Postman' plugin, but its still giving 401 - Unauthorized error. My method is post and have set Process Model and WEB API security as all user Administrator. Kindly find attached screen shot of code and plz guide if anything looks wrong.

@Simples: Just click on web api name in expression rule and changed to get request then you are able find url , Copy that url try to call from
HTTP Query Smart service.
1. Once you copy url from expression rule you NEED TO change request from GET to POST.
2. Create third party credentials in admin console.
3. Make sure security of web api and proess model.

Hi @venkatesh thanks for help but i need to call it out side appian environment. i tried Postman, SoapUI and restClient app, when i am trying with RestClient App in same session it is working but if i try in other browser or after logging out appian environment, its giving 401 Unauthorized error.
Also regarding third party credential, can you please explain detail, i talked with support team but they said they are not aware about anything like this.

@simples, The authorization is not required to be specified in the Web API code.
You need to specify it in Postman - that is in the client which will call the Web API. How are you calling it via Postman? Can you post a screenshot?

And Third Party credentials are not required here. The WEB API is being exposed to outside systems. Appian is not using other systems in this case.

@chetan i have commented that authorization code in the Web API, yes i did same, specified in Postman. Please find attached screenshot of postman. also regarding third party credential, as i need to allow other application to access our appian Web API, don't we will be requiring it, as we do in case of publishing a process model as web service ?