CODEWITHSUNDEEP
javajco
Mango
Mango

Reputation: 660

Could not load middleware layer 'com.sap.mw.jco.rfc.MiddlewareRFC'

I'm using SAP JCo to connect to SAP system with the front end being Java (JSF), When I connect to SAP system with the below code, I have a problem when running the application for the first time, data is displayed but when I re-run it says

Could not load middleware layer 'com.sap.mw.jco.rfc.MiddlewareRFC'

Can any one help me in resolving the issue?????

Code:

try {
  mConnection =JCO.createClient("400", // SAP client
     "c3026902", // userid
     "********", // password
     "EN", // language
     "iwdf5020", // host name
     "00"); // system number
  mConnection.connect();
}
catch (Exception ex) {
  ex.printStackTrace();
  System.exit(1);
}

Upvotes: 0

Views: 7851

Answers (3)

oviwonkenovi
oviwonkenovi

Reputation: 181

Defining SAP connection:

For the Version 3,0 of the sapjco library there exists plenty of useful information. To create a connection following the instructions in:

http://www.browseye.com/linkShare.html?url=http://help.sap.com/saphelp_nwpi711/helpdata/en/46/fb807cc7b46c30e10000000a1553f7/content.htm?bwsCriterion=%22Setting%20Up%20Connection%22&bwsMatch=1&bwsCriterion=%22Setting%20Up%20Connection%22&bwsMatch=1

There are a few thing that you should take into account:

Place the dll file in the same place that the jar. The dll must be the right version for your operating system and architecture otherwise you will get a native library error.

Example of code to create a connection to the server.

public class StepByStepClient
{
    static String DESTINATION_NAME1 = "ABAP_AS_WITHOUT_POOL";
    static String DESTINATION_NAME2 = "ABAP_AS_WITH_POOL";
    static
    {
        Properties connectProperties = new Properties();
        connectProperties.setProperty(DestinationDataProvider.JCO_ASHOST, "ls4065");
        connectProperties.setProperty(DestinationDataProvider.JCO_SYSNR,  "85");
        connectProperties.setProperty(DestinationDataProvider.JCO_CLIENT, "800");
        connectProperties.setProperty(DestinationDataProvider.JCO_USER,   "homofarber");
        connectProperties.setProperty(DestinationDataProvider.JCO_PASSWD, "laska");
        connectProperties.setProperty(DestinationDataProvider.JCO_LANG,   "en");
        createDestinationDataFile(DESTINATION_NAME1, connectProperties);
        connectProperties.setProperty(DestinationDataProvider.JCO_POOL_CAPACITY, "3");
        connectProperties.setProperty(DestinationDataProvider.JCO_PEAK_LIMIT,    "10");
        createDestinationDataFile(DESTINATION_NAME2, connectProperties);

    }

    static void createDestinationDataFile(String destinationName, Properties connectProperties)
    {
        File destCfg = new File(destinationName+".jcoDestination");
        try
        {
            FileOutputStream fos = new FileOutputStream(destCfg, false);
            connectProperties.store(fos, "for tests only !");
            fos.close();
        }
        catch (Exception e)
        {
            throw new RuntimeException("Unable to create the destination files", e);
        }
    }


    public static void step1Connect() throws JCoException
    {
        JCoDestination destination =    JCoDestinationManager.getDestination(DESTINATION_NAME1);
        System.out.println("Attributes:");
        System.out.println(destination.getAttributes());
        System.out.println();
    }
}

In SAPJco 3.0 connections are build from the info contained in a “Destination”.

The documentation example use a properties file to save the “Destination”. However it is a non-secure way to keep connection info. As is indicated on the documentation in the hightlighted paragraph you can see on next link.

http://help.sap.com/saphelp_nwpi711/helpdata/en/48/5fb9f9b523501ee10000000a421937/content.htm?bwsCriterion=%22In%20practice%20you%20should%20avoid%20this%20for%20security%20reasons.%22&bwsMatch=1

You can keep connection info on a database or any other storage system if you create a custom “DestinationDataProvider” In the Examples provided with the SAPJco library there is an example of how to create a custom DestinationDataProvider.

Upvotes: 0

Stefan Ernst
Stefan Ernst

Reputation: 2781

Are your DLLs located in the Windows system32 folder? If so, are you probably using the wrong architecture? (x64 DLL on 32 bit or vice versa) Also, are the DLLs the same version as the java api? If you have SAP GUI installed there could be older DLLs around.

Upvotes: 0

Sebastian
Sebastian

Reputation: 11

This sounds like the API cannot load the native driver files. The SAP Java Connector consists of a native runtime part, that does the actuall communication and a Java API that wraps this functionality with a java api. The Java API is inside the sapjco.jar and the native drivers are e.g on windows inside librfc32.dll and sapjcorfc.dll. Place these dll's into your system path (e.g. windows: C:\WiNDOWS\system32) and it should run.

Cheers Sebastian

Upvotes: 1

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