In this section, we will modify the PowerBuilder application source code and the PowerServer project settings to achieve the following results:
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Gets the user credential from the application login window, then authenticates it with the Azure AD tenant and gets a token.
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Uses the token to access data from the PowerServer Web API.
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Refreshes the token when necessary.
Step 1: Declare the following global variables.
//Token expiresin Long gl_Expiresin //Refresh token clockskew Long gl_ClockSkew = 3
Step 2: Define a global function and name it f_Authorization().
Select from menu File > New; in the New dialog, select the PB Object tab and then select Function and click OK to add a global function.
This global function uses the HTTP Post method to send the user credentials to the authorization server and then gets the identity token from the HTTP Authorization header.
Add scripts to the f_Authorization() function to implement the following scenario:
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Scenario 1: Supports Client Credentials (GrantType="client_credentials") and gets the client ID and secret from the application.
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Scenario 2: Supports Resource Owner Password (GrantType="password") and gets the username and password from a login window.
Scripts for scenario 1:
When the application starts, the application uses the client ID and secret stored in the application to get the token from Azure AD, and when the token expires, it automatically refreshes the token.
Note that: If the ClientSecret value contains the escape character "~", you will have to replace it with "~~", like the example below.
//Integer f_Authorization() for client_credentials //UserName & Password from login window OAuthClient loac_Client TokenRequest ltr_Request TokenResponse ltr_Response String ls_url, ls_UserName, ls_UserPass String ls_TokenType, ls_AccessToken String ls_type, ls_description, ls_uri, ls_state Integer li_Return, li_rtn li_rtn = -1 ls_url = profilestring("CloudSetting.ini","setup","TokenURL","") //TokenRequest ltr_Request.tokenlocation = ls_url ltr_Request.Method = "POST" ltr_Request.clientid = "49cddad2-721d-4fbc-bd64-1cfa2b183e00" ltr_Request.clientsecret = "2ig8hfliVu.u1kl_79RbyZuh~~.X_b~~e~~3M" ltr_Request.granttype = "client_credentials" ltr_Request.Scope = "49cddad2-721d-4fbc-bd64-1cfa2b183e00/.default" loac_Client = Create OAuthClient li_Return = loac_Client.AccessToken( ltr_Request, ltr_Response ) If li_Return = 1 and ltr_Response.GetStatusCode () = 200 Then ls_TokenType = ltr_Response.gettokentype( ) ls_AccessToken = ltr_Response.GetAccessToken() //Application Set Authorization Header Getapplication().SetHttpRequesTheader("Authorization", ls_TokenType + " " + ls_AccessToken, true) //Set Global Variables gl_Expiresin = ltr_Response.getexpiresin( ) li_rtn = 1 Else li_Return = ltr_Response.GetTokenError(ls_type, ls_description, ls_uri, ls_state) MessageBox( "AccessToken Falied", "Return :" + String ( li_Return ) + "~r~n" + ls_description ) End If If IsValid ( loac_Client ) Then DesTroy ( loac_Client ) Return li_rtn
Scripts for scenario 2:
When the application starts, the client ID and secret stored in the application as well as the username and password from the login window will be sent to Azure AD to get the token, and when the token expires, the login window displays for the user to input the username and password again.
The following scripts hard code the username and password instead of getting them from the login window. You can change the scripts to use the login window after you implement the login window and return the username and password to the f_Authorization() function.
Note that: If the ClientSecret value contains the escape character "~", you will have to replace it with "~~", like the example below.
//Integer f_Authorization() for password //UserName & Password from login window OAuthClient loac_Client TokenRequest ltr_Request TokenResponse ltr_Response String ls_url, ls_UserName, ls_UserPass String ls_TokenType, ls_AccessToken String ls_type, ls_description, ls_uri, ls_state Integer li_Return, li_rtn li_rtn = -1 ls_url = profilestring("CloudSetting.ini","setup","TokenURL","") //TokenRequest ltr_Request.tokenlocation = ls_url ltr_Request.Method = "POST" ltr_Request.clientid = "49cddad2-721d-4fbc-bd64-1cfa2b183e00" ltr_Request.clientsecret = "2ig8hfliVu.u1kl_79RbyZuh~~.X_b~~e~~3M" ltr_Request.scope = "49cddad2-721d-4fbc-bd64-1cfa2b183e00/.default" ltr_Request.granttype = "password" //login window can be implemented to return username & password according to actual needs //Open(w_login) //Return:UserName & Password ls_UserName = "appeon2@powerservertest.onmicrosoft.com" ls_UserPass = "Test2008aaBB" If IsNull ( ls_UserName ) Or Len ( ls_UserName ) = 0 Then MessageBox( "Tips", "UserName is empty!" ) Return li_rtn End If If IsNull ( ls_UserPass ) Or Len ( ls_UserPass ) = 0 Then MessageBox( "Tips", "Password is empty!" ) Return li_rtn End If ltr_Request.UserName = ls_UserName ltr_Request.Password = ls_UserPass loac_Client = Create OAuthClient li_Return = loac_Client.AccessToken( ltr_Request, ltr_Response ) If li_Return = 1 and ltr_Response.GetStatusCode () = 200 Then ls_TokenType = ltr_Response.gettokentype( ) ls_AccessToken = ltr_Response.GetAccessToken() //Application Set Authorization Header Getapplication().SetHttpRequesTheader("Authorization", ls_TokenType + " " +ls_AccessToken, true) //Set Global Variables gl_Expiresin = ltr_Response.getexpiresin( ) li_rtn = 1 Else li_Return = ltr_Response.GetTokenError(ls_type, ls_description, ls_uri, ls_state) MessageBox( "AccessToken Falied", "Return :" + String ( li_Return ) + "~r~n" + ls_description ) End If If IsValid ( loac_Client ) Then DesTroy ( loac_Client ) Return li_rtn
Step 3: Insert a timing object (timing_1) to the application and add the following scripts to the Timer event of timing_1.
1) Open the application object and then select from menu Insert > Object > Timing to add a timing object to the application.
2) Add the following scripts to the Timer event of timing_1.
//Authorization f_Authorization()
When displayed in the source editor, the Timer event looks like this:
event timer;//Authorization f_Authorization() end event
Step 4: Add the following scripts to the application Open event.
Place the scripts before the database connection is established. The scripts get the token from Azure AD and then start the user session (using the BeginSession function) to include the token information in the session.
Do not call BeginSession more than one time, otherwise, it will return -1 (indicating session already exists).
//Authorization If f_Authorization() <> 1 Then Return End If //StartSession long ll_return Try ll_return = Beginsession() If ll_return <> 0 Then Messagebox("Beginsession Failed:" + String(ll_return), GetHttpResponseStatusText()) End if Catch (Throwable ex) MessageBox("Throwable", ex.GetMessage()) Return End Try //Refresh Token for timing If gl_Expiresin > 0 And (gl_Expiresin - gl_ClockSkew) > 0 Then //Timer = Expiresin - ClockSkew //7200 - 3 timing_1.Start(gl_Expiresin - gl_ClockSkew) End If // Connect db
Step 5: Add the following scripts to the SystemError event.
The scripts will trigger the SystemError event when the session or license encounters an error; and if the token is invalid or expires, the scripts will call the f_Authorization function to get the token again.
Choose Case error.Number Case 220 to 229 //Session Error MessageBox ("Session Error", "Number:" + String(error.Number) + "~r~nText:" + error.Text ) Case 230 to 239 //License Error MessageBox ("License Error", "Number:" + String(error.Number) + "~r~nText:" + error.Text ) Case 240 to 249 //Token Error MessageBox ("Token Error", "Number:" + String(error.Number) + "~r~nText:" + error.Text ) //Authorization f_Authorization() Case Else MessageBox ("SystemError", "Number:" + String(error.Number) + "~r~nText:" + error.Text ) End Choose
Create an INI file in the same location as the PBT file and name it CloudSetting.ini.
The INI file specifies the URL for requesting the token from Azure AD.
[Setup] TokenURL=https://login.microsoftonline.com/0ffb9ae0-c080-4913-aa94-ed08b5de4d40/oauth2/v2.0/token
By default, the user session is automatically created when the application starts; and the session includes no token. For the session to include the token, the session must be started manually by code instead of automatically.
To start the session manually by code,
Step 1: Select the "Dynamic session parameters" option in the PowerBuilder IDE. (Steps: Open the application object painter, click Additional Properties in the application's Properties dialog; in the Application dialog, select the PowerServer tab and then select the Dynamic session parameters option and click Apply.)
Step 2: Call the BeginSession function in the application Open event (See step 4 in "Add scripts").
After the "Dynamic session parameters" option is enabled, when the BeginSession function is called, it will create a session that includes the token information.
Step 1: Add the INI file CloudSetting.ini to the Files preloaded in uncompressed format section under the Application page.
Step 2: Select RESTClient Support under the Runtime files group in the Application page > Advanced tab.
Step 3: Double check that Use external Azure Active Directory service is selected from the Auth Template list box in the Security page.
Step 4: Save the changes and deploy the PowerServer project (using the "Build & Deploy PowerServer Project" option) so that the above settings can take effect in the installable cloud app.