Hi Anneke,
In this case you need to listen to asynchronous TCP/IP request from external server. I do not think creating an adapter will be able to handle this request. Secondly you also need to write to the external server, then two kinds of adapter are required. Creating an adapter is not a easy task and if I were you I would have looked for alternative solution. The reason being after creating these adapters there is question of maintaining the same , doing troubleshoots etc. The project would require to hire highly skilled professional who can handle such troubleshoots. I was thinking on this for quite some time now and here I suggest a little different design than what was suggested earlier.
case 1:
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The External server is initiating/sending the request to PI.
Solution:
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1. You need a server code(S) which runs in PI server and listens to a specific port.
This code may be written in java or c or c++. As soon as any request arrives to S it writes the request down in a file.
2. In PI design a simple File to idoc scenario. The sender file adapter will pick up the file written by S and send it to ECC. You need to be careful that PI does not pick up the file before S completes writing to it. (Please refer to this thread.)
3. Ecc receives request message from PI and ABAP code in background creates appropriate response.
external server---request-->S----->writes file----->read by PI ------idoc---->SAP R/3
Case2.
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1. ECC initiates the communication (or sends a response) suing RFC/Proxy to PI server.
2. In PI java mapping code (similar to the one in blog mentioned by you) communicates the response/request to the external server.
3. The mapping code also sends back status to ECC on whether writing to external server was successful or not.
ECC--->RFC------->PI------>ext server
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ECC<---RFC<------Status
I think developing this scenario will much easier than writing new adapter code.
I am sure this design can be realized without any confusion. In case you face any issues please share the same
with the forum.
Regards
Anupam