How do I automate SAP GUI with c#

This might be necro-threading but I was in a similar situation where I work. We needed SAP GUI Automation for testing purposes that could integrate with the rest of our homegrown automation platform written in C#. I helped create a proposal for one solution that took advantage of a SAP provided library for GUI automation that could be used as the basis for an automation layer for SAP.

Does the following file exist on your SAP file installation? x:\Program Files\SAP\FrontEnd\SAPGui\sapfewse.ocx?

If so, add it to Visual Studio (or whatever IDE you're using) as a reference. It is basically a class library which contains a bunch of SAP specific objects that will allow you to interact with. It is very effective because it exposes most of what you need from the SAP GUI. We discovered in other attempts that a lot of the objects in SAP were not available.

This is an early proof of concept I did. Start SAP with a connection string, enter credentials, navigate to a transaction code.

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using SAPFEWSELib;

namespace SAPGuiAutomated
{
//created a class for the SAP app, connection, and session objects as well as for common methods. 
    public class SAPActive
    {
        public static GuiApplication SapGuiApp { get; set; }
        public static GuiConnection SapConnection { get; set; }
        public static GuiSession SapSession { get; set; }

        public static void openSap(string env)
        {
            SAPActive.SapGuiApp = new GuiApplication();

            string connectString = null;
            if (env.ToUpper().Equals("DEFAULT"))
            {
                connectString = "1.0 Test ERP (DEFAULT)";
            }
            else
            {
                connectString = env;
            }
            SAPActive.SapConnection = SAPActive.SapGuiApp.OpenConnection(connectString, Sync: true); //creates connection
            SAPActive.SapSession = (GuiSession)SAPActive.SapConnection.Sessions.Item(0); //creates the Gui session off the connection you made
        }

        public void login(string myclient, string mylogin, string mypass, string mylang)
        {
            GuiTextField client  = (GuiTextField)SAPActive.SapSession.ActiveWindow.FindByName("RSYST-MANDT", "GuiTextField");
            GuiTextField login  = (GuiTextField)SAPActive.SapSession.ActiveWindow.FindByName("RSYST-BNAME", "GuiTextField");
            GuiTextField pass  = (GuiTextField)SAPActive.SapSession.ActiveWindow.FindByName("RSYST-BCODE", "GuiPasswordField");
            GuiTextField language  = (GuiTextField)SAPActive.SapSession.ActiveWindow.FindByName("RSYST-LANGU", "GuiTextField");

            client.SetFocus();
            client.text = myclient;
            login.SetFocus();
            login.Text = mylogin;
            pass.SetFocus();
            pass.Text = mypass;
            language.SetFocus();
            language.Text = mylang; 

            //Press the green checkmark button which is about the same as the enter key 
            GuiButton btn = (GuiButton)SapSession.FindById("/app/con[0]/ses[0]/wnd[0]/tbar[0]/btn[0]");
            btn.SetFocus(); 
            btn.Press();

        }
    }
    //--------------------------//
    //main method somewhere else 
    public static void Main(string[] args)
    {
        SAPActive.openSAP("my connection string");
        SAPActive.login("10", "jdoe", "password", "EN");
        SAPActive.SapSession.StartTransaction("VA03");
    }

You're right there is not a lot of documentation on this subject. Below are a few sources that helped me get started

-Original source of our plan http://scn.sap.com/thread/1729689

-Documentation on the API (For VB and javascript but the general rules and objects are identical). Definitely read the portion on the SAP GUI Runtime hierarchy. It'll answer a lot of questions. http://www.synactive.com/download/sap%20gui%20scripting/sap%20gui%20scripting%20api.pdf