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JCo - Can someone tell me how the GWHOST and GWSERV values are derived?

StephenBurr
Active Contributor
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We have successfully been using JCo for some years now in a web application. However, recently on our TST server this has started failing.

The exception is this:

com.sap.mw.jco.JCO$Exception: (102) RFC_ERROR_COMMUNICATION: SAP_CMINIT3 : rc=20 > Connect to SAP gateway failed

Connect_PM GWHOST=127.0.0.1, GWSERV=3301, SYSNR=01

I can see why this is failing ... because the GWHOST and GWSERV are incorrect! However, I don't know why they are wrong when we have the correct logon properties specified and the correct entry in the "services" file on our Windows server.

Can someone tell me how the GWHOST and GWSERV values are derived?

For information our logonProperties file contains:

jco.client.client=900

jco.client.user=webupdate

jco.client.passwd=<hidden>

jco.client.lang=EN

jco.client.mshost=ecctst

jco.client.r3name=TST

jco.client.group=WEB_USER

Services file contains this entry:

sapmsTST 3601/tcp

We establish a connection using

JCO.addClientPool("R3", 10, logonProperties ) ;

Accepted Solutions (1)

Accepted Solutions (1)

ravindra_bollapalli2
Active Contributor
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hi stephen,

those will come from the r3 side

those properties will be given the while installing the r3

gwhost Gateway host

gwserv Gateway service

host and service will be taken from the r3

if u check dynaimically u an refer this link for more details

http://help.sap.com/saphelp_nw04/helpdata/en/22/042a4b488911d189490000e829fbbd/content.htm

let me know u need anyfurther information

ravindra

StephenBurr
Active Contributor
0 Kudos

Thanks Ravinda.

What I am asking is how JCo got these parameters? (given that I only defined a connection by the logonProperties I send)

If they are taken from R/3 then how did JCo get them?

And more importantly is there a test I can run on my application side to prove that the wrong GWHOST and GWSERV is being returned to JCo (and hence my connection fails)?

Stephen

ravindra_bollapalli2
Active Contributor
0 Kudos

> What I am asking is how JCo got these parameters? (given that I only defined a connection by the logonProperties I send)

> If they are taken from R/3 then how did JCo get them?

> And more importantly is there a test I can run on my application side to prove that the wrong GWHOST and GWSERV is being returned to JCo (and hence my connection fails)?

hi stephen,

when we are using the jco as middle layer to acces the backend R/3

http://help.sap.com/saphelp_nw04/helpdata/en/8b/91222fa9e611d6b28f00508b6b8a93/content.htm

the above thread refer the how the our java application will call the R/3

that

http://help.sap.com/saphelp_nw04/helpdata/en/bc/42e13d82fcfb34e10000000a114084/content.htm

this will check

then

/people/gregor.wolf3/blog/2004/08/26/setup-and-test-sap-java-connector-outbound-connection

refer the above blog for how the prcess is going on

http://help.sap.com/javadocs/nw04s/current/jc/com/sap/mw/jco/JCO.Server.html

the methods will give the all the details of the R/3 details by using the jco.server

let me know u need more clarification or details

ravindra

StephenBurr
Active Contributor
0 Kudos

Thanks again for your posts.

Forgetting the application programming as I know this is correct (because our DEV and PRD systems work!), I'm trying to ascertain why, when my logon properties contain the correct gateway and mshost, the application server doesn't try to connect to our TST SAP system (instead it goes to the local host 127.0.0.1 on port 3301, for a reason I don't understand).

In other words, what is JCo doing to establish a connection?

Are there any tests I can run manually to prove the same connectivity?

e.g. an obvious one is that I need to be able to see the TST SAP server (ecctst in my example above), so "ping ecctst" has to work. Which it does.

I've also tried "telnet <ip address> 3601" and that works fine too.

The "services" file looks correct.

I strongly believe this is network related issue but can't think or run a test to prove or explain it!

From the posts so far, I'm going to try 2 things:

1) Put on the JCo trace using "jco.server.trace Enable/disable RFC trace (1 or 0)"

2) Try connecting from our DEV application to our SAP TST system (to prove it isn't the application or SAP TST system that is causing the problem)

Stephen

Answers (0)