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Read Dictionary Meta Data with a Single Server Connection

gregorw
Active Contributor
0 Kudos

Hello,

I've Enterprise Portal 6.0 SP4 NetWeaver Stack 2 Developer Workplace Sneak Preview from https://www.sdn.sap.com/sdn/downloads.sdn running on my computer and implemented the Tutorial: "Creating A Web Dynpro Application Accessing ABAP Functions" from https://www.sdn.sap.com/sdn/developerareas/webdynpro.sdn?page=TutWD4_AccessingABAP.htm.

During the setup of the JCo Conneciton for the WD_FLIGHTLIST_RFC_METADATA_DEST in the Web Dynpro Content Administrator in Step 3 I came across the problem that I can not use a Single Server Connection to read Dictionary Meta data.

So my Question: Why is it not possible to read Dictionary Meta Data with a Single Server Connection?

Regards

Gregor

Accepted Solutions (0)

Answers (5)

Answers (5)

Former Member
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The problem disappeared.

Former Member
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Hi Gurus,

I had same issue with that. Is there anyone had the solution with that?

Thanks,

Bo

ruth_groene
Advisor
Advisor
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Hi,

if you encounter the symptom that the single server connection to a system works but the Load-balanced connection doesn't, you can try the following two steps:

1. Check that a logon group is defined in transaction * SMLG * of the R/3 system.

(If there is none, enter a name, e.g. 'PUBLIC', in the box at the beginning that is empty by default. I'm not sure, but you may have to select the option 'Enable RFC' on the properties tab)

2. Enter the required R/3 system into your services file on the WebAS server and restart the WebAS afterwards (the restart is necessary).

You can find the services file in folder

C:\WINDOWS\system32\drivers\etc .

Sample entry for a system called 'IDX' with system number 00:

sapmsIDX 3600/tcp # SAP IDX Message Port

Hope this helps,

Ruth

Former Member
0 Kudos

Hi Ruth,

Thanks for the guideline.

I entered an entry in the etc/service file on the m/c which is having SAP WAS 6.40 J2ee installed.(let say ip address 172.16.1.38)

for e.g.

sapmsSA1 3600/tcp

I restated the webAS server.

Then from SAP GUI when i am connecting to SAP R/3 backend system and checking the 'smlg' transaction.....i can see 3 Logon groups with the same name 'PUBLIC'.

Now i have created the BC Message server connection in SLD with this information.

caption - SA1 01

Message server IP = 172.16.1.242

port 3600

After that i specified this message server information to WD_MetaData connection in JCO content administrator.

When i tetsed this connection it gives me error as follow.

com.sap.mw.jco.JCO$Exception:(102) RFC_ERROR_COMMUNICATION: Connect to SAP gateway failed

connect_PM TYPE=B MSHOST=172.16.1.242 GROUP=PUBLIC R3NAME = SA1 MSSERV=sapmsSA1 PCS=1 LOCATION CPIC(TCP/IP)on localhost with Unicode ERROR partner not reached(host 172.16.1.38,service sapgwoo)

connection refused

can u guide me what i am missing?

Thanks,

Mital.

Former Member
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Hi Ambadas

Is 00 your instance number ? Did you try a machine restart after the service entry

Regards

Pran

Former Member
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So can I ask, how do you setup the Metadata JCO in a single server system? I have the sneak preview WAS Server Java 6.4 (J2EE) and I have also installed the MINIWAS 6.2. I have successfully setup the SLD and imported the 2 zip files. I can start SAP, and through SM59 test connect to SLD_NUC. I can use RZ70 to 'send' info. I can successfully load, build, archieve the Flightlist demo. I can go to http://localhost:50000/Webdynepro/welcome. and create and test the Model data under JCO connections (not using load balancing). When I test 'metadata_dest' I get the RFC_error_communication Group Public not found. I tried your fix (services fiel sapmsBSP 3200, but this makes it not possible to connect to sap since SAP listens on port 3200. Any thoughts? Can I spoof my system to think its has load balancing?

Thanks

Former Member
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Russ,

From where did u get the MiniSAP downloadable from net?

I dont have the book with which the CDs ara available as gift.

Also there is some installation manual available for MiniSAP?

Thanks.

gregorw
Active Contributor
0 Kudos

Hello Ambadas,

if you are a Linux user you can download the Web AS Testdrive 6.40 from ftp://ftp.sap.com/pub/linuxlab/test_drive/ or order Web AS 6.10 from http://www.sap.com/solutions/netweaver/linux/eval/was/ for free.

Regards

Gregor

Former Member
0 Kudos

Hello Russ:

I was wondering if you will be so nice to tell me how you configure SLD_NUC at SM59. I can not created because it already exists and it have the connection type: TCP/IP connection and I can not change it.

I configured at the SM59 RFC destinations ->

R/3 connections -> double click at BSP which is my system ID and completed Gateway options with my was 6.20 data (IP and sapgw00 as service). The Targethost is my was 620 too. The connection test works OK !!! but when I go back RZ70 and test it (pressing the clock button) a line which didn´t appear before:

"RFC call failed: program SLD_NUC not registered / CPI-C error CM_ALLOCATE_FAILURE_RETRY.

How can I resolve it ?

I missing a set up ?

Thanks a lot.

Former Member
0 Kudos

There are two reasons for reading dictionary metadata in a separate connection:

1) Special priviledges are required to read dictionary metadata. Usually the RFC user does not have this permission.

2) Dictionary metadata is cached and reused by ALL users on the frontend. This means, that you have a max of one connection per J2EE node for reading dictionary metadata, even if you have 250 concurrent RFC connections being used by 250 different user sessions. In general, this is the best compromise between performance, scalability, and administrative overhead.

Hope that helps.

Best regards, karin

gregorw
Active Contributor
0 Kudos

Hello Karin,

I understand why to use two connections. What I don't understand is why can the connection for the metadata only be a connection through a load balancer? Especially if this connection is reused by ALL users of the frontend.

For me it would be more logical that the data connection must be established through a load balancer to share the load of the different users. But here I have the choice.

Regards

Gregor

Former Member
0 Kudos

Hi Karin and Gregor,

IMO it should be possible for developers to use any "type" of connection for metadata retrieval at least for development and testing purposes.

Development and testing systems of customers are often <b>not</b> load balanced. What are the options in this case? Tell the customer to change the systems just for the sake of WD development? She/he will probably drop off the chair laughing.

Best regards

Stefan

gregory_hawkins1
Employee
Employee
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Hi Stefan,

I am not a systems person, but I am on a ramp up project and their development boxes are not load balanced and did not have login groups, so we couldn't initially make the needed meta data connection for adaptive RFC. I discussed it with the basis person who provided me a new login group to build my meta data JCO connection in less than 15 minutes. It was apparently some configuration he had to do to make it look like a load balanced system.

Like I said, I don't know what was done, but it wasn't any big deal for my customer.

Does someone want to provide the details on how to configure a system that was previously only a single application server to appear like a load balanced system?

Thanks,

--Greg

Former Member
0 Kudos

Hi Greg,

i know, that this is possible, but anyway you have to struggle sometimes with customer's "basis people" even to get this kind of easy changes applied, since they want to change as less as possible (the good old never change a running system paranoia).

I don't know (all) the steps required to fake a load balanced system, so it would be nice, like you said, if somebody could document this here.

On the other hand, it would be even more easy <b>not</b> to insist on load balanced metadata connections in the WD content admin. A simple warning like "Please do not use this type of connection for metadata access in productive systems" would be enough. If i use it in productive scenarios and performance collapses, it's my fault. Another option would be a simple true/false flag in the WD configuration, which must be activated to allow the use of any kind of connection for metadata in the WD content admin.

Thanks and best regards

Stefan

Former Member
0 Kudos

Hi Greg,

Can you please tell what changes they made to make single server look like load balanced?

Thanks,

Mital.

ruth_groene
Advisor
Advisor
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Hi Mital,

one necessary step for getting the connection to work is to define one logon group in transaction * smlg * of the R/3 system.

(Enter a name, e.g. 'PUBLIC', in the box at the beginning that is empty by default.)

Best regards

Ruth