First you should understand that this is a painfull to migrate from JSF 1.x
to jsf 2.x
but it is even more painfull to migrate from Richfaces 3
to Richfaces 4
.
JSF 1.x to 2.x upgrade can be done independently from Richface upgrade. So I would recommend you first update JSF and check that everything is working and only after that try updating Richfaces. Look at this question about JSF migration for more info. Or just google it. There is a lot of info about it.
Richfaces 3 to 4 migration is very very painfull because JSF 2 introduced it's own ajax and you will need to change a lot of attributes all overt the project. But the biggest pain is that Richfaces 3 work much more stable than Richfaces 4. Richfaces 4 is very buggy. I can list some bugs that I encountered and some solutions for them.
rich:autocomplete
is very buggy. Not sure if it is fixed already
but when I tried using it it was not working with Spring in
composite views(<ui:include
pages). After I sumbitted bug report
they seem to do something there but not sure if this works now. I
didn't check. https://issues.jboss.org/browse/RF-11469
I would advise you to replace this component with simple jQuery UI
autocomplete component with some spring mvc controller on backend.
rich:tabPanel
is very buggy. Separate tabs do not have action
attribute any more. This was breaking functionality with initing tab
contents when the tab was opened with ajax. Immediate attribute also
not working for tabs. Here is the issue on jboss jira: https://issues.jboss.org/browse/RF-11417 workaround is really stupid.
I just went into source code of richfaces and made it working.
Exception handling is very buggy. Seems that exceptions are just
swallowed in many places in richfaces source on ajax requests so you
can not handle them the right way.
I went again into Richfaces code and removed exception swallowing by
throwing out exceptions.
rich:fileUpload
component can work and can not work for you. You
can get request prolog can not be read
exception in some
cases(This is what I was getting). And This is connected with new
app server feature of reading multipart request into
request.getParts(). And Richfaces do not handle such situation and
error out because inputstream of multipart request is already read
fully.
I again went to source code of Richfaces and added catch for
situation when request.getParts is not empty. I even created an
issue on Jboss but guys said this works on new Jboss server that's
why it is not an issue(I use tomcat). https://issues.jboss.org/browse/RF-13061 the issue is close still it is not working on tomcat.
A lot of issues on client side. By default multiple forms will not
work on your pages like they were working in jsf 1.2 and richfaces 3
because the viewstate id is not updated where and when it needs to
be.
To fix this you will need to add additional script. It is described
in the answer to this question
Also on the client side you should know that if in the response of
any ajax request you will have some js that will fail everything
stops working. You can not have js errors inside xhtml. The page
will freeze completelly. Also it is tricky to have CDATA
tags on
the xhtml pages. They can also fail.
Richfaces messages work the way that sometimes they show up and
sometimes not. They are ajax rendered but seems that they can break
the page. Ajax reposnse can have an update that should update
messages that is not rendered on the page and when it will not find
this message in your html it will stop rendering everything that is
left to update. As a result your links and buttons will not rerender
anything in some cases.
Here evaluating limitRender
attribute helps a lot.
It is a short list. There probably a lot more to be aware of and that you will see after update =)) Richfaces 4 are still buggy.