Monthly Archives: February 2005

AOP@Work Part 1 Comments

I have enjoyed very much the comparison Mik Kersten is presenting in the first part of AOP@Work series. I have been around AspectJ and AspectWerkz for a while, I’ve read the documentation of Spring, but never got the oportunity to go deeper into JBossAOP. So I was happy to read a quick intro to all of them.
I would state from the beginning that in my opinion AspectJ and AspectWerkz are the strongest solutions (and surely the AJ5 project will be the best).
However, the reason behind this entry was to point out one difference (very important imo) between the analysed solutions: JBossAOP and Spring are still interceptor based solutions. (their implementation is probably based on proxies; offering join point context through reflection API) and because of this they are presenting some limitations: non-real before, after (with all the different flavors) advices (NB: I think that the correct form is pieces of advice), harder control flow usage.
And yet another thing: this interceptor based AOP will be pushed into the EJB3 spec (but about this I will talk on another entry).

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Eclipse, SSH and PuTTY

Yesterday was a great day for me: been accepted as a commiter to AspectWerkz project (thanks again Alex and Jonas, you are just great! – I will write more about this some other time).
And now the short story: I got to set up my environment to access CVS using SSH with keys. I think every developer has successfully done this once – this is why I’ve been a little pissed off. I have generated the keys using ssh-keygen and than another pair with PuTTY. By looking at them I have noticed that they are very differnt. Why this?
But let’s continue. Finally the PuTTY generated public key was placed on the server and now the long series of tries begun: ssh client (from cygwin) was refusing to connect. Turning verbose mode on (you place up to 3 -v options in the command line) I have found out that indeed the private key was not recognized. I have gone back to using PuTTY and I have successfully logged in.
Next step would be having WinCVS and Eclipse connected. In order to shorten the story, I made WinCVS work with Pageant and ssh protocol (i didn’t know about it, and I don’t think this is correct – as I should use ext or extssh protocol). With Eclipse, I have successfully connected using plink and ext protocol but not with Eclipse SSH support and extssh protocol (probably because of the keys incompatibility, it was failing to connect with an unpleasant/non-explicative message: Auth fail).

I would like to find out what I was doing wrong and how I can do the following:

  • make WinCVS work with ext or extssh protocol (probably using plink)
  • make Eclipse extssh connection work (so not using plink)

A very nice solution for CVS is also TortoiseCVS (thanks Alex for the suggestion. It works nice with pageant).

Update: Euxx has posted more hints on Eclipse and CVS usage.


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Three (maybe more) steps to AOP

Through Dion I have read the AOP initialization guide published by Richard Monson-Haefel. Wow! It would be great to be so easy. Unfortunately I have the feeling that it is not like this (hey guys everybody would already got the mind on fire after so many years of AOP and only 3 steps to get it). Moreover, I think that these 3 steps may in fact lead you to wrong conclusions: aop will solve your logging problems; aop is not standard and maybe the most dangerous one: aop is interception.
I know this, because they all happened to me [damn-it/]. I have been tricked by these during the years I have tried to get to AOP. I’ve met AOP ideas a few years ago. I have jumped to AspectJ in his early days and I didn’t like it – why? because it was not pure java, because I couldn’t find much applicability. At those days J2EE was pushed high and I got to JBoss with their interception ideas used inside the container. And I have been tricked again: AOP is interception. It took me longer to put me back on the right track and to really understand what AOP is. I guess I have got the the real picture after reading a couple of AOP papers and definitely after reading a book – that absolutely great book of Ramnivas AspectJ in Action. Nowadays the AOP presentation is more powerfull than ever: the most powerfull project AspectJ with its upcoming AJ5 and a full set of books to cover and introduce you to the AOP world. These days it will be harder to fall to the same mistakes I’ve made. But still beware! Choose carefully your first (3 or more) steps to AOP and don’t be afraid to ask if you are on the correct side of the street.

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