Is there a possibillity of install a component on all websites in one installation?
Or do I have to install the extension one site at the time?

With JMS 1.2.x, this can be do into 2 steps.

You have to install the extension on the master website and after, you have 2 possiibilities.
- If you have create a slave sites with a template that reference the master, you just have to open and resave the salve site to synchronize all the new extension present in the "parent" website delcared in the template
- OR you can go in the "tools" menu to select the extension that you want to install/share or install into a slave sites and its children slave sites.
remark: in the Tools, the extension must be known by JMS (check the icon and symbol to know if it is know). If this is not the case, you have to send me an email with the extension that you would like to be declared in JMS. I will review this extension to do the reverse engineering concerning the DB tables that are associated to this extension.
I have design the possibility to distribue such update using the "check for update".

So if you want to propagate the installation to a lot of slave site, it is good to organize them in such way that you can use the "propagate to children" facility.
See User Manual chapter 3.4 for the explaination and page 34 for the screenshot.

HI

I too am interested this so have a question about your comment..

If this is not the case, you have to send me an email with the extension that you would like to be declared in JMS. I will review this extension to do the reverse engineering concerning the DB tables that are associated to this extension.

Please coul you tell us what is required so that we can do this? I often write my own components and modules, and we will need to propogate them to all sites. So option 1 is no good, so option 2 we will have to do, but it would seem reasonable that I do this myself instead of asking for you to do it, from which there may be a possibility you say no.

Thanks a lot

If you are writing your own extension that you would like to be added in the JMS tool for the installation then send us the package of the extension to allow us reviewing the extension and declare all the MySQL tables used by the extension to allow it installation.
Otherwise, the JMS Tool is not able to replicate the MySQL tables used by the extension.

You can not do yourself as this concern a configuration that is present in the core of Jms Multisite. If you modify it, it will be destroyed when you will update JMS multisite