News

On Linkage

Here's the situation: you make a spiffy new blog entry / news item in your spiffy CMS linking to another place in the spiffy CMS. Like this. Doesn't seem that complicated, but consider if this blog entry / news item gets reused elsewhere in the site on, for example, the front page. This is happening more frequently now, since there are other interesting reuse opportunities in new CMSs like page compositing. Perhaps the most proliferic use is giving each user a blog, and then aggregating all user blogs on the front page.

Now, how was your link formed? This is a big deal, and can cause a lot of grief. Here are a few choices, with some comments:

• Relative URL: href="../gallery/computers"
• This kind of link will break if the blog entry / news item is moved.
• It also breaks if the blog entry is used elsewhere. The path "../gallery/computers" doesn't exist when the item is, for example, shown on the front page.
• It also breaks if 'computers' is relocated.
• The only real plus side is that this link is easy to get right with most popular in-browser editors.
  
• Site Relative URL: href="/Members/fprimex/gallery/computers"
• This is much better, and will survive moving the blog entry / news item.
• It also works if the blog entry is used elsewhere. After all, no matter where you are on the site, "/Members/fprimex/gallery/computers" points to the same place.
• However, the link breaks if 'computers' is relocated or renamed.
• It's not very friendly to ask your CMS users to get links like this right.
  
• Absolute URL: href="http://www.fprimex.com/Members/fprimex/gallery/computers"
• This type of link has all of the effects of a Site Relative URL, with the additional negative of breaking if the domain name of the site changes.
  
• Site Reference: something like href="/stuff_finding_script?item=3764898"
• This link will survive moving, being used elsewhere, and relocating / renaming 'computers'. Drupal has links like this when you use "/node/19369172".
• One downside is that the link is not easy to remember and is ugly compared to something meaningful like '/Members/fprimex/gallery/computers'.
• Another downside is that doubling up on links (where both 'computers' and '/stuff?item=38' are used to point to the same piece of content) is a search engine scoring no-no.
  
• We're only concerned with internal links within the site here, but keep in mind that someone, somewhere may reference 'computers' using the nice URL and not the Site Reference way. If the nice URL is ever changed, the link breaks.

The landscape for making good internal links looks pretty dismal. But wait! There may yet be some hope for easy to create, quality linkage.

What I've decided to do in Plone

By default, it's hard to predict what kind of links you're going to get out of Plone using the Kupu editor. This is truely unfortunate, because it's such a big part of managing content. I think other in-browser, javascript based editors suffer from this problem - they're at the mercy of browser makers, after all. Here's some fun you may run into (from this email):

Some of the transformations which may happen to your links:

When you start editing in Kupu, IE will convert all links from relative to absolute.

During editing, Firefox will sometimes convert absolute links to relative (if you drag/drop images Firefox will convert absolute links to the *wrong* relative links which will break the images unless you also enable the link-by-uid feature).

When you save, Kupu will convert all absolute links to relative (obviously only where the links can be expressed as relative). Also, if you have enabled the link-by-uid feature it will reduce such links down to just a 'resolveuid' call.

When the page is rendered it is possible that some transforms may run on the page. One such transform supplied with Kupu but not enabled by default will replace all the 'resolveuid' links with the absolute url for the target. If you are using Apache rewrites this will result in an absolute http://www.somedomain.com link rather than the somehost:8080 link from when you edited the page.

The link-by-uid feature sounds pretty nice, but how is it different than the Site Reference above? Will it put ugly '/resolveuid/1928479' links throughout my site? The answer is thankfully 'no', and link-by-uid is a very good solution in almost all cases. Head to the Kupu settings and just tick the link-by-uid checkbox. Here's what happens:

• User inserts a relative link using the content browser in Kupu
• In the editor, this link will show up as a 'resolveuid/12093879eeoai' type of link
• When the page is viewed, the page goes through a portal transform that finds the content item and puts in our nice Site Relative URLs.

The only downside I can see is that you might take a performance hit resolving these UIDs on view, but this can be mitigated with caching. This type of link also suffers from the "someone, somewhere using the nice URL" problem, but remember we're mostly only concerned with links within the site.

Link-by-uid is a great way to do your internal linkage!

Full circle - Python web frameworks

A little over a year ago I got serious about doing web development using Python. From what I have discovered, this is not exactly an easy field to break into and understand without either guidance or a lot of hard work. The first thing I had to do was choose a framework, and this was during a time when the number of viable frameworks seemed to be on the rise.

This is no longer the case.

Ultimately, I chose to use Plone and got some guidance from a Plone Bootcamp. You may be thinking "Plone is a CMS, not a framework" and I'll get to that in a minute. Recently, a project came up which presented the opportunity to review my choice with greater insight and a bit of experience. Also, a friend had just chosen to use CherryPy for a new project he is undertaking. What should I use for my new project? It's not exactly a website in the traditional sense. This will be a special purpose web application, the way I thought about web applications when I got started in all of this.

What is out there, available as open source, with enough of an established base to allow me to successfully implement my project?

• Zope based
  • Zope 3
  • Plone
  • Grok
• Django
• Turbogears
• Pylons
• CherryPy

This list is longer than the one given in the article linked above, but still justifiable. Each of these presents some interesting choices, but the list can be reduced somewhat with a small amount of research and expressing some preferences.

First off, I would rather reuse a quality component or mechanism than do it myself from scratch. This means I'm after a full featured framework rather than a DIY framework like CherryPy. Nothing wrong with CherryPy, it just doesn't provide anything other than the extreme basics - focus on processing requests. For example, CherryPy does not use a templating system by default, allowing you to use whatever you want. Now we have to evaluate templating systems. There is no default database for persistence, etc etc

Interestingly, Turbogears uses CherryPy as its application server and includes all of the 'best of breed' tools. The pieces have already been assembled in a usable way, allowing you to get to developing your application. Turbogears is considered a 'mega framework' because of this. Pylons is similar in this respect in that it assembles various tools that can be swapped out. Pylons uses the Paste application server instead of CherryPy at its heart. Pylons has a Ruby on Rails style of request handling.

CherryPy/Turbogears and Pylons can be reduced into one choice, keeping in mind the preferences expressed, and because the next version of Turbogears will actually not use CherrPy, but will instead run on top of Pylons! The communities are combining and I think this is great. CherryPy itself will probably continue to have a small hardcore following, but lose the support of developers working on things like Turbogears.

Django seems like the odd one out with other communities folding into each other. There is a great community around it and it has certainly been put through its paces in the professional world. Again, the common tools such as templating and persistence are in place. However, there are a couple of things that Zope/Plone has over Django, in my opinion. Not only that, but Django is very focused on the news / blog style of application. I know it can be used to do just about anything, but it's designed to make those kinds of applications easy.

Zope 3, Plone, and Grok all share a common Zope heritage in some way. They all make use of the Zope Object Database, ZODB, for persistence and use Zope Page Templates (ZPT). Plone is actually a Zope 2 CMS product that can also use Zope 3 development techniques through a project called Five (Zope 2 + Zope 3 = Five), which is now built in to Zope 2.

Grok is being worked on to become "Zope 3 for the common caveman", however, I am discovering that Grok is missing enough substance that nearly any complex web application will need to dip down into its Zope 3 base to make it work. One only needs to consider user management to see that Grok has a way to go to stand on its own. There's nothing wrong with this, except that if you already know enough Zope 3 to get a complex Grok application off the ground, you're probably already using Zope 3.

Any reasonably mature framework based on Zope at this point is battle tested and worthy of enterprise consideration. I'm a big fan of ZPT because they render in a browser, making them easy to write. I'm also a big fan of the ZODB because it is about the slickest persistence available and I'm a programmer, not a system administrator. The ZODB is often unfairly knocked on performance when in fact it is efficient, quite scalable thanks to ZEO, and able to handle heavy loads.

Zope, Django, and Pylons/Turbogears are all definitely worth considering. Obviously, I have had some good experiences with Zope technology and am leaning that way. Here's the thing though: a lot of what I'm after in a generic web application framework is already there with Plone, and it can be turned on and off easily (or so it would seem). These kinds of things, like user management, authentication, a sophisticated portlet and layout system, have to be built up in even an advanced framework like Zope 3. Additionally, the future of Plone development is using buildout, which should make it possible to quickly pull together the components needed without too much cruft.

All the above having been said, for the second time I am looking at choosing Plone. This time around, however, the application will be more like a one-shot, specific use application and not really resemble content management at all. I believe this process has given me a much better understanding of the "Plone as an application vs Plone as a framework" sentiments.

I'm currently reading through Web Component Development with Zope 3 and Professional Plone Development. I'm not much of a blogger, but I'll post what I eventually decide to implement this project in. It may even get released to the world if I do a good enough job!

Send-to form spammers

Ugh. Spammers are truly the bottom feeders of the internet. I discovered recently that my development site was being used to send unsolicited email. My sincerest apologies to anyone who got junk mail from an fprimex.com address.

I have fixed the problem, and outlined for other Plone users below some precautions to take so that they too don't get used to make the spam problem any worse.

The main issue is that Plone has a feature through which you can email a link to someone using an online form. It's a "I bet Bob would want to see this", click send-to, put Bob's email into the form, click send scenario. Unfortunately, this feature is available to anyone and can be repeatedly abused by scripts and lowlifes.

Here's a checklist to get rid of Plone's send-to functionality:

1. Take the "Allow sendto" permission away from everyone
   1. In the Zope Management Interface (ZMI) of your Plone site, select the "Security" tab.
   2. Scroll down to the "Allow sendto" permission and uncheck all of the boxes in its row, including "Acquire".
   3. This will make it so that people can still reach the sendto form, but when they attempt to send, they'll get an error. This is the minimum to fix the problem.
2. Remove the sendto document action
   1. In the ZMI of your Plone site, select portal_actions
   2. In portal_actions, select document_actions
   3. Either of these achieves the same effect for end users:
      1. Delete sendto
      2. Select sendto, then uncheck Visible
3. Replace the sendto_form page with a disabled message
   1. In the ZMI of your Plone site, select portal_skins
   2. Select the plone_forms folder
   3. Select the sendto_form, then click the Customize button
   4. In the template, delete the form and replace it with something like "This form has been disabled."

Note that doing only #2 will still allow spammers to reach and use the sendto form if they know the URL.

UFC 84, Gaming Club, Coding

Congratulations to BJ Penn for getting an amazing TKO win over Sean Sherk at UFC 84. I have been keeping up with the UFC on pay per view for several years now, and 84 was a great buy. They showed 9 of the 11 fights, and only 1 of the 9 shown went to a decision. Even the decision fight (Ortiz vs. Machida) was entertaining.

Leander has been hard at work putting up game servers for the ASU Gaming Club. There's something for just about everyone if you like 1st person shooters. We've got TF2, CS 1.6 and Source, Quake 3 and 4, UT2004 (with UT3 on the way), and a host of military shooters - DoD, CoD4, and BF2. Get all the info here, then come out and play some.

I want to code something, but I've realized that I won't continue working on a program that I don't make use of at least sometimes. Work on LAD has stalled again, despite the long to-do list I made for it months ago. I just don't do graph theory every day (or at all any more, for that matter). I'd like to do something with Panda3D or the ZODB. I've also pretty much given up on managing my own code repository. My next open source project will probably be on Sourceforge or Google Code somewhere.

I'm noticing lots of hits on my development site. If you're getting a lot of the information there feel free to drop me a line and let me know what you think.

Python Lab, LANs, ZODB, web stuff, Zero Punctuation

• Support is deployed!
• ALUG Python Lab March 27th, 7 to 9PM, JET 387
  • General Python get-together
• ALUG LAN Party March 29th, 10AM to 10PM, JET 387
  • Games and geeking out, win stuff from the radio station
• Gaming Club LAN Party April 19th, 12 noon to 11PM, ASU Grandfather Ballroom
  • Gaming LAN with tournamets and about 150-200 gamers
• Posted introduction to using the ZODB (Zope Object Database) on dev
• So awesome: Zero Punctuation
• FYI - I'm now rewriting fprimex.com to www.fprimex.com
• Trac 0.11 needs to hurry up and come out
  • I'm thinking - move dev to Trac and www to Plone.... maybe

Catching up

The new, Plone based, support website for Appalachian has been deployed. Work has also now started on aspects of the website that have been in planning for many months. Exciting times!

Speaking of Plone, my Introduction to Plone talk was given twice for the ALUG, along with the most recent talk, Introduction to wxPython. I haven't decided what to do for the last talk in the ALUG Python series, which is scheudled for 3/27, but it was suggested to host a lab. The Python Lab idea would give people a chance to work on what they wanted to do, but be able to get help.

One attendee of the Plone talk has launched a new Plone site about older computers that could be pretty cool.

Maybe now I can get some more work done on LAD. Working with Sage has so far been a bust, so I'm just going to go ahead with my own stuff for now. Hopefully we can collaborate and converge in the future.

Finally, let's end on an interesting note: XML-RPC thick client for Plone? I'm updating the code on that page (from 8 years ago!) and will hopefully come up with something cool soon.