Tips

How to Send a File to Multiple Hosts at the Same Time

Introduction

Have you ever wished you could transfer a file to multiple hosts at the same time?
HULFT has a convenient feature called multicasting, which allows you to send a file to multiple hosts by issuing a single request.

In HULFT, you specify the destination host for each file ID.
However, you can also specify a group of hosts via what is called Transfer Group Information, instead of specifying detailed Host Information directly for the File ID.

In addition, because you can use the same Transfer Group Information for multiple File IDs, you don't need to edit every File ID when you want to increase the number of hosts to which to send the file. All you have to do is edit the Transfer Group Information, and you are done!
By using HULFT in this way, you can increase the operational efficiency of the destination hosts.

In this tip, We will explain how to use multicasting, as well as some important things to keep in mind when you use it.

How to Use Multicasting

In HULFT, you can manage the destination hosts to which you want to send files by grouping them.
In this tip, We will explain how to do this by using an example of adding new Host Information from Transfer Information that already exists.

1. Edit the Transfer Group Information.

Make these changes on the sending host.
Open the Transfer Group Information List, and edit the Transfer Group ID - GRP00 which already been set up.

In the edit screen for the Transfer Group Infromation Update, add the host name for the host that you want to add. Then, save the edits.
Note that the maximum number of hosts that can be specified for a single Transfer Group ID is 1,000.

2. Check the Send Management Information.

On the sending host, check the Send Management Information, and issue a Send File.

3. Confirm the transfer results.

In the Send Log Iist, confirm that the file was sent to all hosts in the Transfer Group Information (including the 3 new hosts that you added).

Notes on Using Multicasting

Multicasting differs from performing a single transfer. As such, there are several things you should keep in mind when using it.
Please check the following points before you use multicasting.

• - You can use multicasting only when you issue a Send File.

When you issue a Send Request, the file is sent only to the host that issues the Send Request.

• - In the Send Management Information, for Send File Mode, you must specify Send (K).

If you specify Clear (C), Delete (D), or Lock (L), an error occurs.

- Even if the file is to be sent to multiple destination hosts, the pre-send job is executed only once for each time you execute the send processing.

• - If you are using an open operating system or AS/400, the post-send job is executed once for each host, even if the file is sent to multiple hosts by executing the send processing only once.

If you are using a mainframe operating system, the post-send job is typically executed only once, when the processing to send the file to all hosts ends normally.
However, the job that is registered to be performed in case of abnormalities is executed once for each host for which an abnormality occurs.

• - Send processing is carried out for each host that is registered in the Transfer Group Information.

Because of this, even if an error occurs on one host, the job is queued for resending only on the host on which the error occurred.
However, be aware that when you issue a Resend File, the pre-send job is not executed, even if a pre-send job ID is registered.
In addition, if an error occurs on even one host when you use multicasting, the return value for the command will be something other than 0, indicating an error.

- Regarding operations when you issue a new Send File when the previous transfer is still in progress for only one host, due to a slow network connection (when the transfer to all other hosts is completed)

• Example: When you use multicasting to send a file to Host A, Host B, and Host C, and then attempt to perform another multicasting transfer after the first file has been completely transferred to Hosts A and B, but while the first transfer to Host C is still in process.

- Host A and Host B => The second file is transferred.
- Host C => If you attempt to start a new transfer while the transfer processing for the first transfer is still in progress, the first transfer will not be canceled, and the new transfer will not be ignored.
However, depending on the settings for Send Process Multiplex Level and Send process Multiplex Level by Host, the multiplex level might be exceeded. If this happens, the later send processing might be queued for sending.
In addition, depending on the settings for Receive Process Multiplex Level, the multiplex level might be exceeded. If this happens, the processing that was later acknowledged by the receiving host might result in a Receive Multiplex Level error.

Conclusion

So, what do you think?
Multicasting is an extremely convenient feature. To use it, you only need to specify simple settings.
Some of you are probably already using it, but we hope that you will check the cautionary notes in this tip in order to conduct stable operations.