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SAP PI SFTP Adapter Interview Questions and Answers

In case of PGP the keys are to be kept on the files system whereas for SFTP the keys are stored in the keystore.

Ans: PGP Key-rings is used by PGP adapter which is a special format that the SAP J2EE engine does not support and therefore the keys cannot be stored in the keystore.

The keys can't be converted into the *.p12 format that the engine supports (like in SFTP's case).

The File Write Operation Always Fails in SFTP Receiver Channel

Ans: Some SFTP Server implementations such as GXS, deviates from RFC and their responses for few operations will differ from the normal SFTP Servers. In some scenarios, when PI SFTP Adapter generates a request in order to check the existence of a given file, it will reply with positive and the attributes will have a directory flag. PI SFTP Adapter will perform this check prior of writing the file and it fails due to the unexpected behaviour.

Advanced mode table is added in both Sender and Receiver channels. If the directory check needs to be removed before writing the file, the parameter 'skipRemoteDirCheck' can be configured with any non-null value. 

File Retrieve operation fails with "inputstream is closed" error.

Ans: Some SFTP Server implementations have a too slow response time for a file-get request because SAP PI SFTP Adapter uses a higher buffer size as default (65535), 'get request'will fail with an error.

This problem can be solved by using a lesser custom buffer size. It can be configured via advanced mode parameter "receiveBufferSize". The legal values should be between 1 to 65535. 

SFTP Adapter appends "_" after the configured file while using Add Time Stamp or Add Message-ID options

Ans: This additional suffix should be removed to be compatible with existing standard PI adapters like File Adapter.
Adding underscore after the file will be removed if Add Time Stamp or Add Message used. 

The duplicate check option is valid for the files which are processed in past 14 days. There is no option to define the custom value

Ans: In order to provide the flexibility to define the duplicate check validity, configuration option needs to be provided. The 'duplicateCheckPersist' parameter can be configured in advanced section of sender channel. The values should be in minutes. For example,  10 days should given as 14400 (10 * 24 * 60). Any incorrect value will fallback to 14 days. For more information, see NOTE: 1744700.

Can PGP Module (which uses OpenPGP standards) handle keys generated using "PGP 6.5.8" software?

Ans: No, we can make the keys work with the SAP PGP module by formatting the keys, however, the PGP software will not work with the formatted keys.

Zombie connections in per file transfer mode.

Ans: If login timeout error occurs when SFTP adapter is trying to create a connection to SFTP server through a connection handle, some SFTP servers create a child process (automatically spawned from OS level) from the parent process which timed out previously. This child process now waits to establish a connection with the client, keeping it alive.

As the client did not get the connection handle to the server as a result of the timeout, it is not possible to disconnect zombie child connection from client/adapter side.
This behavior is observed in some SFTP servers and can be observed/analyzed from the SFTP server logs/traces.