Write a Simple Go Application to work with SAP Ariba Source Data on Linux

Go is an open source programming language that enables you to easily build software on Linux/UNIX machines. When Go is paired with the ODBC Driver for SAP Ariba Source and unixODBC you are able write applications with connectivity to live SAP Ariba Source data. This article will walk you through the process of installing the ODBC Driver for SAP Ariba Source, configuring a connection using the unixODBC Driver Manager, and creating a simple Go application to work with SAP Ariba Source data.

Using the CData ODBC Drivers on a Unix/Linux Machine

The CData ODBC Drivers are supported in various Red Hat-based and Debian-based systems, including Ubuntu, Debian, RHEL, CentOS, and Fedora. There are also several libraries and packages that are required, many of which may be installed by default, depending on your system. For more information on the supported versions of Linux operating systems and the required libraries, please refer to the "Getting Started" section in help documentation (installed and found online).

Installing the Driver Manager

Before installing the driver, you need to be sure that your system has a driver manager. For this article, you will use unixODBC, a free and open source ODBC driver manager that is widely supported.

For Debian-based systems like Ubuntu, you can install unixODBC with the APT package manager:

apt-get install unixodbc unixodbc-dev

For systems based on Red Hat Linux, you can install unixODBC with yum or dnf:

yum install unixODBC unixODBC-devel

The unixODBC driver manager reads information about drivers from an odbcinst.ini file and about data sources from an odbc.ini file. You can determine the location of the configuration files on your system by entering the following command into a terminal:

odbcinst -j

NOTE: You may need to install odbcinst. Use the following command in a terminal:

apt install odbcinst

The output of the command will display the locations of the configuration files for ODBC data sources and registered ODBC drivers. User data sources can only be accessed by the user account whose home folder the odbc.ini is located in. System data sources can be accessed by all users. Below is an example of the output of this command:

DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/myuser/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

Installing the Driver

You can download the driver in standard package formats: the Debian .deb package format or the .rpm file format. Once you have downloaded the file, you can install the driver from the terminal.

The driver installer registers the driver with unixODBC and creates a system DSN, which can be used later in any tools or applications that support ODBC connectivity.

For Debian-based systems like Ubuntu, run the following command with sudo or as root:

dpkg -i /path/to/package.deb

For systems that support .rpms, run the following command with sudo or as root:

rpm -i /path/to/package.rpm

Once the driver is installed, you can list the registered drivers and defined data sources using the unixODBC driver manager:

List the Registered Driver(s)

odbcinst -q -d
CData ODBC Driver for SAP Ariba Source
...

List the Defined Data Source(s)

odbcinst -q -s
CData SAPAribaSource Source
...

To use the CData ODBC Driver for SAP Ariba Source with unixODBC, you need to ensure that the driver is configured to use UTF-16. To do so, edit the INI file for the driver (cdata.odbc.saparibasource.ini), which can be found in the lib folder in the installation location (typically /opt/cdata/cdata-odbc-driver-for-saparibasource), as follows:

cdata.odbc.saparibasource.ini

...

[Driver]
DriverManagerEncoding = UTF-16

Modifying the DSN

When the driver is installed, a system DSN should be predefined. You can modify the DSN by editing the system data sources file (/etc/odbc.ini) and defining the required connection properties. Additionally, you can create user-specific DSNs that will not require root access to modify in $HOME/.odbc.ini.

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.

/etc/odbc.ini or $HOME/.odbc.ini

[CData SAPAribaSource Source]
Driver = /opt/cdata/cdata-odbc-driver-for-saparibasource/lib/libsaparibasourceodbc.x64.so
Description = My Description
API = SupplierDataAPIWithPagination-V4
APIKey = wWVLn7WTAXrIRMAzZ6VnuEj7Ekot5jnU
Environment = SANDBOX
Realm = testRealm
AuthScheme = OAuthClient
InitiateOAuth = GETANDREFRESH

For specific information on using these configuration files, please refer to the help documentation (installed and found online).

Creating a Simple Go App for SAP Ariba Source Data

With the Driver Manager installed and the DSN configured, you are ready to create a simple Go application to work with your SAP Ariba Source data. To start, install a Go driver for ODBC databases. While there are several options available, this article will use the odbc driver found at https://github.com/alexbrainman/odbc.

Installing ODBC on Linux

There are a series of steps required to install the ODBC driver for Go.

1. Create the $HOME/golang/go path (if it does not exist) by entering the following commands in a terminal:

   mkdir /root/golang
   mkdir /root/golang/go
    

2. Define the GOPATH environment variable:

   export GOPATH=$HOME/golang/go
    

3. Create a module inside the new Go directory:

   cd $GOPATH
   go mod init myproject
    

4. Install the Go driver for ODBC databases:

   go get http://github.com/alexbrainman/odbc
    

Now you are ready to create and execute a simple Go application.

Sample Go Application

The sample application issues a simple SQL SELECT query for SAP Ariba Source data and displays the results. Create the directory $GOPATH/src/cdata-odbc-saparibasource and create a new Go source file, copying the source code from below.

cdata-odbc-saparibasource.go

package main

import (
 _ "github.com/alexbrainman/odbc"
 "database/sql"
 "log"
 "fmt"
)

func main() {
 db, err := sql.Open("odbc",
 "DSN=CData SAPAribaSource Source")
 if err != nil {
 log.Fatal(err)
 }

 var (
 smvendorid string
 category string
 )

 rows, err := db.Query("SELECT SMVendorID, Category FROM Vendors WHERE Region = ?", "USA")
 if err != nil {
 log.Fatal(err)
 }
 defer rows.Close()
 for rows.Next() {
 err := rows.Scan(&smvendorid, &category)
 if err != nil {
 log.Fatal(err)
 }
 fmt.Println(smvendorid, category)
 }
 err = rows.Err()
 if err != nil {
 log.Fatal(err)
 }

 defer db.Close()
}

In the terminal, navigate to the Go application directory and build the application:

go build

After the application builds, you will be able to execute the application, displaying your SAP Ariba Source data:

./cdata-odbc-saparibasource

At this point, you have a simple Go application for working with SAP Ariba Source data. From here, you can easily expand the application, adding deeper read/write functionality through familiar SQL queries.