Write a Simple Go Application to work with SAP Netweaver Gateway Data on Linux

Use CData ODBC drivers and unixODBC to create a simple Go app with live connectivity to SAP Netweaver Gateway data.

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 Netweaver Gateway and unixODBC you are able write applications with connectivity to live SAP Netweaver Gateway data. This article will walk you through the process of installing the ODBC Driver for SAP Netweaver Gateway, configuring a connection using the unixODBC Driver Manager, and creating a simple Go application to work with SAP Netweaver Gateway 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 Netweaver Gateway
...

List the Defined Data Source(s)


odbcinst -q -s
CData SAPGateway Source
...

To use the CData ODBC Driver for SAP Netweaver Gateway 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.sapgateway.ini), which can be found in the lib folder in the installation location (typically /opt/cdata/cdata-odbc-driver-for-sapgateway), as follows:

cdata.odbc.sapgateway.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.

SAP Gateway allows both basic and OAuth 2.0 authentication. You can use basic authentication to connect to your own account, or you can use OAuth to enable other users to retrieve data from your service with their accounts. In addition to authenticating, set the following connection properties to access SAP Gateway tables.

Url: Set this to the URL of your environment, or to the full URL of the service. For example, the full URL might appear as: https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/. In this example, the environment URL would just be: https://sapes5.sapdevcenter.com.
Namespace: Set the appropriate Service Namespace. In the example above, IWBEP is the namespace. It is optional if the full URL to the service is specified.
Service: Set this to the service you want to retrieve data from. In the example above, the service is GWSAMPLE_BASIC. It is not required if the full URL is specified.

Authenticate via Basic Authentication

In basic authentication, you use your login credentials to connect. Set the following properties:

User: This is the username you use to log in to SAP Gateway.
Password: This is the password you use to log in to SAP Gateway.

Authenticate via OAuth Authentication

You can connect to SAP Gateway using the embedded OAuth connectivity (without setting any additional authentication connection properties). When you connect, the OAuth endpoint opens in your browser. Log in and grant permissions to complete the OAuth process. See the OAuth section in the online Help documentation for more information on other OAuth authentication flows.

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


[CData SAPGateway Source]
Driver = /opt/cdata/cdata-odbc-driver-for-sapgateway/lib/libsapgatewayodbc.x64.so
Description = My Description
User = user
Password = password
URL = https://sapes5.sapdevcenter.com/sap/opu/odata/IWBEP/GWSAMPLE_BASIC/

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 Netweaver Gateway Data

With the Driver Manager installed and the DSN configured, you are ready to create a simple Go application to work with your SAP Netweaver Gateway 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.

Create the $HOME/golang/go path (if it does not exist) by entering the following commands in a terminal: mkdir /root/golang mkdir /root/golang/go
Define the GOPATH environment variable: export GOPATH=$HOME/golang/go
Create a module inside the new Go directory: cd $GOPATH go mod init myproject
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 Netweaver Gateway data and displays the results. Create the directory $GOPATH/src/cdata-odbc-sapgateway and create a new Go source file, copying the source code from below.

cdata-odbc-sapgateway.go


package main

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

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

  var (
    productid string
    quantity string
  )

  rows, err := db.Query("SELECT ProductID, Quantity FROM SalesOrderLineItems WHERE Quantity = ?", "15")
  if err != nil {
    log.Fatal(err)
  }
  defer rows.Close()
  for rows.Next() {
    err := rows.Scan(&productid, &quantity)
    if err != nil {
      log.Fatal(err)
    }
    fmt.Println(productid, quantity)
  }
  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 Netweaver Gateway data:


./cdata-odbc-sapgateway

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

Ready to get started?

Download a free trial of the SAP Netweaver Gateway ODBC Driver to get started:

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Learn more:

SAP Netweaver Gateway ODBC Driver

The SAP Netweaver Gateway ODBC Driver is a powerful tool that allows you to connect with live data from SAP Netweaver Gateway, directly from any applications that support ODBC connectivity.

Access SAP Netweaver Gateway data like you would a database - read, write, and update SAP Netweaver Gateway Entities, etc. through a standard ODBC Driver interface.