A PostgreSQL Interface for SAP Ariba Source Data using the CData ODBC Driver

There are a vast number of PostgreSQL clients available on the Internet. From standard Drivers to BI and Analytics tools, PostgreSQL is a popular interface for data access. Using the SQL Gateway included in our ODBC Drivers, you can now create PostgreSQL entry-points that you can connect to from any standard client.

To access SAP Ariba Source data as a PostgreSQL database on Windows, use the CData SQL Gateway, the ODBC Driver for SAP Ariba Source, and the MySQL foreign data wrapper from EnterpriseDB. In this article, we compile the foreign data wrapper in Visual Studio, install it as an extension, and query SAP Ariba Source data from PostgreSQL Server.

Configure the Connection to SAP Ariba Source

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

In order to connect with SAP Ariba Source, set the following:

• API: Specify which API you would like the provider to retrieve SAP Ariba data from. Select the Supplier, Sourcing Project Management, or Contract API based on your business role (possible values are SupplierDataAPIWithPaginationV4, SourcingProjectManagementAPIV2, or ContractAPIV1).
• DataCenter: The data center where your account's data is hosted.
• Realm: The name of the site you want to access.
• Environment: Indicate whether you are connecting to a test or production environment (possible values are TEST or PRODUCTION).

If you are connecting to the Supplier Data API or the Contract API, additionally set the following:

• User: Id of the user on whose behalf API calls are invoked.
• PasswordAdapter: The password associated with the authenticating User.

If you're connecting to the Supplier API, set ProjectId to the Id of the sourcing project you want to retrieve data from.

Authenticating with OAuth

After setting connection properties, you need to configure OAuth connectivity to authenticate.

• Set AuthScheme to OAuthClient.
• Register an application with the service to obtain the APIKey, OAuthClientId and OAuthClientSecret.

  For more information on creating an OAuth application, refer to the Help documentation.

Automatic OAuth

After setting the following, you are ready to connect:

APIKey: The Application key in your app settings. OAuthClientId: The OAuth Client Id in your app settings. OAuthClientSecret: The OAuth Secret in your app settings.

When you connect, the provider automatically completes the OAuth process:

1. The provider obtains an access token from SAP Ariba and uses it to request data.
2. The provider refreshes the access token automatically when it expires.
3. The OAuth values are saved in memory relative to the location specified in OAuthSettingsLocation.

Start the Remoting Service

The MySQL remoting service is a daemon process that listens for clients' incoming MySQL connections. See the setup guide in the SQL Gateway overview to configure the MySQL Remoting service in the CData SQL Gateway.

Build the MySQL Foreign Data Wrapper

The Foreign Data Wrapper can be installed as an extension to PostgreSQL, without recompiling PostgreSQL. If you are running PostgreSQL on a Unix-based system, you can use the PostgreSQL Extension Network (PGXN) to install the FDW, mysql_fdw. If you are running PostgreSQL on Windows, compile the extension to ensure that you are working with the latest version. Follow the steps below to make the necessary modifications to build the extension from Visual Studio:

Obtain Prerequisites

To build the foreign data wrapper, do the following:

• Install PostgreSQL. This example uses an installation of PostgreSQL 9.4.
• Obtain the source for the mysql_fdw foreign data wrapper from EnterpriseDB.
• Install MySQL Connector C. This example uses an installation of MySQL Connector C 6.1.

Configure a Project

After you have obtained the necessary software and source code, you are ready to compile the extension with Visual Studio. Follow the steps below to create a project using the mysql_fdw source:

1. In Visual Studio, create a new empty C++ project.
2. In Solution Explorer, right-click Source Files and click Add -> Existing Item. In the file explorer, select all of the .c and .h files from the mysql_fdw source.

Follow the steps below to configure your project:

1. If you are building for a 64-bit system, click Build -> Configuration Manager and in Active Solution Platform select x64.
2. Right-click your project and click Properties.
3. In the Configuration menu, select All Configurations.
4. In Configuration Properties -> General -> Configuration Type, select Dynamic Library.
5. In Configuration Properties -> C/C++ -> Code Generation -> Enable C++ Exceptions, select No.
6. In Configuration Properties -> C/C++ -> Advanced -> Compile As, select Compile as C Code.
7. In Linker -> Manifest File -> Generate Manifest, select No.

Follow the steps below to add the required dependencies:

1. In Linker -> Input -> Additional Dependencies, select Edit and enter the following:

   postgres.lib
   libmysql.lib
   WS2_32.lib
   Secur32.lib
   

   Additionally, ensure that Inherit From Parent or Project Defaults is checked.
2. In Linker -> General -> Additional Library Directories, select Edit and add
   • the path to the lib folder in your PostgreSQL installation
   • the path to the lib folder for your MySQL Connector C installation
3. In Linker -> General -> Link Library Dependencies, select No.
4. To complete the configuration of your project, add the necessary includes: In C/C++ -> General -> Additional Include Directories, add the following folders in the following order:

   MyMySQLConnectorCInstallation\include
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server\port\win32_msvc
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server\port\win32
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include
   

Configure mysql_fdw for Windows

After setting up a project, make the following changes to build mysql_fdw in Visual Studio:

1. In mysql_fdw.c, add the following defines:

   #define dlsym(lib, name) (void*)GetProcAddress((HMODULE)lib, name)
   #define dlopen(libname, unused) LoadLibraryEx(libname, NULL, 0)
   

2. In the mysql_load_library definition, delete the following line:

   mysql_dll_handle = dlopen(_MYSQL_LIBNAME, RTLD_LAZY | RTLD_DEEPBIND);
   

3. Add the following line in the mysql_load_library definition to replace the assignment of mysql_dll_handle for a Windows build:

   mysql_dll_handle = dlopen("libmysql.dll", 0);
   

4. Prepend the call to the mysql_fdw_handler function with the __declspec(dllexport) keyword to export the function from the DLL:

   __declspec(dllexport) extern Datum mysql_fdw_handler(PG_FUNCTION_ARGS);

5. In option.c, prepend the declaration of the mysql_fdw_validator function with the __declspec(dllexport) keyword to export the function from the DLL:

   __declspec(dllexport) extern Datum mysql_fdw_validator(PG_FUNCTION_ARGS);

You can now select the Release configuration and build.

Install the Extension

After you have compiled the DLL, follow the steps below to install the extension:

1. Add the path to the lib folder for MySQL Connector C to the PATH environment variable of the machine running PostgreSQL.
2. Copy the DLL from the RElease folder for your project into the lib subfolder of your PostgreSQL installation.
3. In the folder containing the mysql_fdw csource files, copy myswl_fdw--1.0.sql and mysql_fdw.control into the extension folder under the share folder of your PostgreSQL installation. For example: C:\Program Files\PostgreSQL\9.4\share\extension.

Query SAP Ariba Source Data as a PostgreSQL Database

After you have installed the extension, follow the steps below to start executing queries to SAP Ariba Source data:

1. Log into your PostgreSQL database. For example:

   C:\> psql -U postgres
   

2. Load the extension for the database:

   postgres=#CREATE EXTENSION mysql_fdw;
   

3. Create a server object for SAP Ariba Source data:

   postgres=# CREATE SERVER SAPAribaSource FOREIGN DATA WRAPPER mysql_fdw OPTIONS (host
   '127.0.0.1', port '3306');
   

4. Create a user mapping for the username and password of a user known to the MySQL remoting service. Below are the credentials for the user in the sample configuration of the service:

   postgres=# CREATE USER MAPPING for postgres SERVER SAPAribaSource OPTIONS (username
   'admin', password 'test');
   

5. Create the local schema:

   postgres=# CREATE SCHEMA SAPAribaSource_db;

6. Import all the tables in the SAP Ariba Source database you defined:

   postgres=# IMPORT FOREIGN SCHEMA "CData SAPAribaSource Sys" FROM SERVER SAPAribaSource INTO SAPAribaSource_db;
   

You can now execute read/write commands to SAP Ariba Source:

postgres=# SELECT * FROM SAPAribaSource_db."vendors";