Mylos longer articles

Aperture: first impressions

First in a series:

  1. First impressions
  2. Asset management
  3. Under the hood: file format internals

Cost and hardware requirements

The first thing you notice about Aperture, even before you buy it, is its hefty hardware requirements. I had to upgrade the video card on my PowerMac G5 (dual 2GHz, 5.5GB RAM) to an ATI X800XT, as the stock nVidia 5200FX simply doesn’t make the cut.

Aperture costs $500, not far from the price of the full Photoshop CS2. Clearly, this product is meant for professionals, just like Final Cut Pro. The pricing is not out of line with similar programs like Capture One PRO, but it is rather steep for the advanced amateurs who have flocked to DSLRs and the RAW format. Hopefully, Apple will release a more reasonably priced “Express” version much as they did with Final Cut Express.

File management

Like its sibling iPhoto, Aperture makes the annoying assumption that it will manage your photo collection under its own file hierarchy. It does not play nice and share with other applications, apart from the built-in Photoshop integration, which merely turns Photoshop into an editor, with Aperture calling all the shots and keeping both image files and metadata databases firmly to itself. Photoshop integration does not seem to extend to XMP interoperability, for instance.

This is a major design flaw that will need to be addressed in future versions — most pros use a battery of tools in their workflow, and expect their tools to cooperate using the photographer’s directory structure, not one imposed by the tool. Assuming one Aperture to rule them all is likely going to be too confining, and the roach-motel like nature of Aperture libraries is going to cause major problems down the road. Copying huge picture files around is very inefficient — HFS supports symbolic and hard links, there is no reason to physically copy files. This scheme also renders Aperture close to useless in a networked environment like a magazine or advertising agency, where media files are typically stored on a shared SAN, e.g. on XServe RAID boxes using Fibre Channel.

Fortunately, the file layout is relatively easy to reverse-engineer and it is probably just a question of time until third-party scripts become available to synchronize an Aperture library with regular Pictures folders and XMP sidecar metadata files, or other asset management and metadata databases like Extensis Portfolio or even (shudder) Canto Cumulus. Apple should not make us jump through these hoops – the purpose of workflow is to boost productivity, not hinder it. In any case, Apple is apparently hinting Aperture can output sidecar files, at least according to PDN’s first look article


Aperture is not the lightning-fast RAW converter we have been dreaming of. Importing RAW files is quite a sluggish affair, taking 2 minutes 15 seconds to import a 665MB folder with 86 Canon Rebel XT CR2 RAW files. In comparison, Bridge takes about a minute to generate thumbnails and previews for the same images. The comparison is not entirely fair, as Aperture’s import process yields high-resolution previews that allow you to magnify the image to see actual pixels with the loupe tool, whereas Bridge’s previews are medium resolution at best. The CPU utilization on my dual G5 is far from pegged however, which suggests the import process was not particularly tuned for SMP or multi-core systems, nor that it even leverages OS X’s multithreading. Aperture will work with other formats like scanned TIFFs as well (import times are even slower, though).

Once import is complete, viewing the files is very smooth and fast. The built-in loupe tool is particularly addictive, and very natural for anyone who has worked with a real loupe on a real light table. A cute visual effect (Quicktime, 6MB) has the loupe flip over as you reach the edges of the screen. The loupe will also magnify the thumbnails, although that will pause execution for the time it takes to read the thumbnail’s preview data into memory.

Workflow innovations

Aperture has two very interesting concept: stacks and versions. Stacks group together multiple images as one. It is very common for a photographer to take several very similar photos. Think of bracketed exposures, or a sports photographer shooting a fast action sequence at 8 frames per second, or a VR photographer making a series of 360-degree shots for use in an immersive panorama. Aperture’s stacks allow you to manage these related images as a single unit, the stack. It is even capable of identifying candidates for a stack automatically using timestamps.


This article is work-in-progress, and this section has to be fleshed out


Versions is a concept clearly drawn from the world of software configuration control systems like CVS or Visual SourceSafe. Aperture does not touch the original image, adjustments like changing the color balance simply record the series of operations to achieve the new version of the image in the metadata database, just like CVS only stores diffs between versions of a file, to save space. This suggests Apple plans future versions of Aperture with shared image repositories, as most modern systems work that way, with a shared central repository, and individual copies for each user, with a check-in/check-out mechanism with conflict resolution.

The parameters for a transform take a trifling amount of memory, and the photographer can experiment to his heart’s content with multiple variants. Photoshop now has equivalent functionality with the introduction of layers comps in CS, but they still feel like bolted-on features rather than integral to the product.

In the early nineties, French firm FITS introduced a groundbreaking program named Live Picture to compete with Photoshop. Its chief claim to fame was that it could deal with huge images very efficiently, because it recorded the operations as a sequence of mathematical transforms rather than the result, in a way eerily reminiscent of PostScript. The transforms were only applied as needed at the display resolution, thus avoiding the need to apply them to the full-resolution image until the final output was required, while still managing to deal with zooming adequately. The software was promising, but the transformation logging technique limited the types of operations that could be performed on images, and due in part to its high price and specialized scope, the product died a slow and painful death. In its current incarnation, it lives on, after a fashion, in the moribund Flashpix image format and a web graphics server program imaginatively named ImageServer.

Chained transforms is a very elegant approach when compared to the brute-force of Photoshop — in Aperture a finished image is represented as a master image and a series of transformations to be applied to it to achieve each version, much like Photoshop keeps a history of changes made to the image in memory (but not in the final disk file). Since Aperture’s transforms are fairly simple, they can be executed in real time by modern graphics cards that support Core Image.

Target market

Keep in mind there are two types of pro photographers: those who divide photographers in two groups, and the others… More seriously:

  1. Those who try to build up a portfolio of images over their career, where royalties and residual rights will provide them with financial support when they retire. Most fine art, landscape or nature photographers are in this category, and photojournalists could be assimilated (except their employer owns the rights to the archive in the latter case).
  2. Those who do work-for-hire. Wedding photographers, event photographers, product, catalog, advertising and industrial photographers fit in this category.

The first type need a digital asset management database to retrieve and market their images more effectively, and a distribution channel. Most farm out that representation work to the likes of Corbis or Getty Images.

The second type will work intensely on a project, take a lot of frames and show many variants to a client for approval. Once the project is done, it is archived, probably never to be used again, and they move on to the next one. In most cases, the rights to the images remain with those who commissioned them, not the photographer, and thus there is no incentive to spend much effort in organizing them with extensive metadata beyond what is required for the project. These users need a production workflow tool that will streamline the editing and client approval process, the latter mostly performed via email or password-protected websites nowadays.

Aperture’s projects (flat, not nested hierarchically, and thus not all that scalable) and vaults (archives where projects go when they are no longer needed or finished) are a clear indication it is intended mostly for the second type of photographer. Apple did not convey the specialized focus of the product forcefully enough, but the blogosphere’s buzz machine bears much of the blame for raising unwarranted expectations about what the product is about.

Aperture is good for one thing: let wedding photographers and the like go through the editing (as in sorting through slides on a light table, not retouching an individual image) as efficiently as possible. Most wedding pros simply cannot afford the time to individually edit a single picture beyond white balance, tonal adjustments, cropping and sharpening, and Aperture’s built-in tools are perfectly adequate for them.

That is also why there is such a slow import process — this prep work is required to make the actual viewing, side by side comparison, sorting and manipulation as smooth, interactive and responsive as possible to avoid disrupting the photographer’s “flow”. The goal is to have a very smooth virtual light table, not a filing cabinet, where you can move slides around, group them in stacks, toy around with versions, and compare them side by side on dual 30 inch Cinema Displays. The user experience was clearly designed around what the average art director (with his or her loupe almost surgically implanted) is familiar and comfortable with.

The positioning as “iPhoto Pro” obscures the fact that Aperture is sub-optimal for managing or indexing large archives with rich metadata. For the first type of pro photographer (which is also what the average advanced amateur will relate to), a digital asset management database like the excellent Kavasoft Shoebox or the more pedestrian but cross-platform and workgroup-oriented Extensis Portfolio and Canto Cumulus will better fit their needs, with Adobe Bridge being probably sufficient for browsing and reviewing/editing freshly imported photos (when it is not keeling over and crashing, that is).


Aperture is clearly a 1.0 product. It shows promise, but is likely to disappoint as the reality cannot match the hype that developed in the month or so between the announcement and the release. The problem is that there is a Cult of the Mac that raises unrealistic expectations of anything coming out of Cupertino.

The hype around Aperture was certainly immense, I am sure Apple was as surprised as any by how positive the response was (after all, they released Aperture at a relatively obscure pro photo show). They are probably furiously revising plans for the next release right now. I consider Aperture 1.0 more a statement of direction than a finished product.

Aperture internals

Last in a series:

  1. First impressions
  2. Asset management
  3. Under the hood: file format internals

This article was never completed because I switched to Lightroom and lost interest. What was done may be of interest to Aperture users, although the data model probably changed since 1.0

Aperture stores its library as a bundle with the extension .aplibrary. This is a concept inherited from NeXTstep, where an entire directory that has the bundle bit set is handled as if it were a single file. A much more elegant system than Mac OS Classic’s data and resource forks.

Inside the bundle, there is a directory Aperture.aplib which contains the metadata for the library in a file Library.apdb. This file is actually a SQLite3 database. SQLite is an excellent, lightweight open-source embedded relational database engine. Sun uses SQLite 2 as the central repository for SMF, the next-generation service management facility that controls booting the Solaris operating system and its automatic fault recovery, a strong vote of confidence by Sun in SQLite’s suitability for mission-critical use. SQLite is also one of the underlying data storage mechanisms used by Apple’s over-engineered Core Data framework.

You don’t have to use Core Data to go through the database, the /usr/bin/sqlite3 command-line utility is perfectly fine for this purpose. Warning: using sqlite3 to access Aperture’s data directly is obviously unsupported by Apple, and should not be done on a mission-critical library. At the very least, make sure Aperture is not running.

ormag ~/Pictures/Aperture Library.aplibrary/Aperture.aplib>sqlite3 Library.apdb
SQLite version 3.1.3
Enter ".help" for instructions
sqlite> .tables
sqlite> .schema z_metadata
ormag ~/Pictures/Aperture Library.aplibrary/Aperture.aplib>sqlite3 Library.apdb
SQLite version 3.3.7
Enter ".help" for instructions
sqlite> .tables
sqlite> .schema zrkfile
sqlite> .schema z_metadata
sqlite> .schema z_primarykey
sqlite> select * from z_primarykey;

One useful command is .dump, which will dump the entire database in the form of the SQL commands required to recreate it. Even with a single-photo library, this generates many pages of output.

Here is my attempt to reverse engineer the Aperture 1.5.2 data model. CoreData, like all object-relational mappers (ORMs) leaves much to be desired from the relational perspective. The fact SQLite foreign keys constraints are not enforced (and not even set by CoreData) doesn’t help. Click on the diagram below to expand it.

Aperture 1.5.1. data model

All tables are linked to Z_PRIMARYKEY which implements a form of inheritance using the column Z_ENT to identify classes. The only table that seems to use this today is ZRKFOLDER, where the rows can have a Z_ENT of 5 (Folder), 6 (Project) or 7 (ProjectSubfolder). For clarity, I have omitted the links between all tables and Z_PRIMARYKEY.

ZRKIMAGEADJUSTMENT looks like the table that records the transformations that turn a master image into a version, Live Image style.

Going all loopy about loupes

Harking back to Kodachrome

My father took most of my childhood photos (like these) on Kodachrome slide film. Kodachrome was the only color game in town for a long time, but was eventually superseded in the marketplace by C41 color print films and finer grained E6 slide film.

Kodachrome has a distinctive sharpness (acutance, not resolution), and excellent durability when stored in the dark. Many photographers still shoot Kodachrome for its special “look”, even though processing options are diminishing and Kodak jacked up the price. Kodak recently announced it is closing its Fair Lawn, NJ processing lab, the last Kodak-owned plant in the US for Kodachrome, and there are now only three labs left worldwide that can run the complicated process (Dwayne’s in Kansas, Kodak in Lausanne, Switzerland, and a lab in Japan). Kodachrome was actually discontinued for a while, and brought back after strident protests, but the writing is on the wall.

Projectors and light tables

Every now and then, we would dust off the slide projector and have a slide show. I even remember building a surprisingly effective slide projector when I was 9 using Legos, a flashlight and a jar of peanut butter filled with water as the lens. Slide projectors are hard to find, a pain to setup and most people groan instinctively when one comes up, associated as they are with dreary slide show of other people’s vacation pictures. The LCD computer monitor is the successor to the projector, and many people no longer have prints made at all, perhaps because they subconsciously realize that the 500:1 contrast ratio of a LCD monitor yields significantly livelier images than prints can achieve.

light table and loupes

A light table is just what the name implies – a piece of frosted plastic illuminated by daylight-balanced fluorescent tubes. Basic models like my Porta-trace shown above are inexpensive. Loupes, on the other hand, are a different story.

Loupe basics

Loupes (French for “magnifying glass”) are high-quality magnifiers, originally used to help focus images on a ground glass, and later to view slides or negatives on a light table. You can find them in all shapes and sizes, at prices from $15 for a cheap plastic model, all the way to over $300 for a Zeiss loupe for viewing 6×6 medium format slides. Slides viewed on a light table with a high-quality loupe are a treat for the eyes, because of the high contrast (1000:1) that you cannot get with prints (more like 100:1).

There are two ways you can use a loupe: use a high-power (10x or higher) to check slides or negatives for critical focus), or a medium-power loupe to evaluate an entire frame (usually 5x-6x for 35mm, 3x-3.5x for medium format). Viewing an entire frame is more challenging than just checking for focus in the center, because the loupe must provide excellent optical quality across the entire field of view. There are variable magnification (zoom) loupes available, but their optical quality is far below that of fixed magnification loupes, and they should be avoided for critical examination of slides or negatives.

I have accumulated quite a few loupes over time. The most famous brand in loupes is Schneider-Kreuznach, a German company noted for its enlarger, medium format and large format lenses. Many other brands make high-quality loupes, including Rodenstock, Pentax, Nikon, Canon, NPC, Leica and Zeiss. I do not live in New York, and have thus not had the opportunity to compare them side by side at a place like B&H Photo, so I pretty much had to take a leap of faith based on recommendations on the Internet at sites like


The Peak was my first loupe. Dirt cheap, and reasonably good for the price, but that’s pretty much all it has going for it (more on that below).


I was put off by reports on the plastic construction of the new line of Schneider loupes, and opted for a Zeiss loupe instead, based on the reputation of Zeiss lenses (my first camera was a Zeiss, and I also have a Zeiss lens on my Hasselblad).

The Zeiss Triotar 5x loupe (the box does not mention Contax, but as it is made in Japan, it is presumably made in the same factory) comes in a cardboard box that can be turned into a protective case by cutting off the tabs on both ends. It does not include a carrying pouch or protective box, which is regrettable, specially for a product as expensive ($160), but apparently most high-end loupe manufacturers do not bother to include one. It does not include a neck strap either, which could be more of an issue for some. How can you look like a glamorous New York art director without a loupe around your neck? More seriously, the strap is particularly useful if you are going to use the loupe for focusing medium or large format cameras against a ground screen.

The loupe is shipped with two acrylic bases that screw into the loupe’s base. One is frosted, and is used as a magnifier to view prints or other objects, with ambient light filtering through the base to illuminate the object. The black base is used to shield out extraneous light when concentrating on a slide or negative on a light table or a ground glass. Some loupes have a design with a clear base and a removable metal light shield. Which design you prefer is mostly a matter of personal taste. The loupe has a pleasant heft to it, and impeccable build quality. The main body of the loupe itself is solidly built of black anodized metal, with a knurled rubber focusing ring.

The optical quality is what you would expect form Zeiss. Crystal clear, sharp across the field of view, and no trace of chromatic aberration in the corners. You can easily view an entire 35mm frame and then some, although I suspect eyeglass wearers might find the eye relief a little bit short.

Edmunds pocket microscope

The Edmunds direct view microscope is a versatile instrument, available in many magnifications, with or without an acrylic base (highly recommended) and with or without a measurement reticle (metric or imperial). Due to the high magnification, the image has a very narrow field of view (only 3mm), and is quite dim. Unlike the others, the image is reversed, which requires some adaptation time. The level of detail you can observe on slides taken with a good film like Fuji Provia 100F, using a good lens and a tripod, is absolutely stunning. This is a rather specialized instrument, but well worth having in your toolkit.


The Rodenstock 3x 6×6 aspheric loupe has a list price of $350 and usually retails for $250. Calumet Photo sells the exact same loupe under their own brand for a mere $149 (I actually got mine for $109 during a promotion), which is not that much more than a cheap (in more ways than price) Russian-made Horizon.

There are naturally fewer loupes available to view medium format slides or negatives than for 35mm. Schneider, Mamiya/Cabin, Contax/Zeiss and Rodenstock make high-grade loupes for this demanding market. If you have a “chimney” viewfinder on your MF camera, you can actually use that as a loupe.

Rodenstock is famous for its large-format and enlarging lenses, and this loupe is very highly rated. The construction is plastic, but still well-balanced and not too top-heavy. It does not carry the feel of opulence that the Zeiss has, or even the very nicely designed Mamiya/Cabin loupes (more on that below), but is still clearly a professional instrument. It has a two-element aspherical design for sharpness across the entire field of view, and coated optics. It comes with a red neck cord, and the base has a removable plastic skirt that slides in place and can be reversed between its clear and dark positions. The eyepiece has a rubber eyecup and a knurled rubber grip for the focusing ring.

I compared it side by side at Calumet San Francisco with the Cabin 3.5x loupe for 6×4.5 or 6×6. The Cabin had a solid metal constuction (somewhat top-heavy), but its screw-in skirts are less convenient than the slide-in one used in the Rodenstock, and the image circle is too tight for my Hasselblad 6×6 slides. I think that loupe was really designed for 645 format and opportunistically marketed for 6×6, when the 6×7 loupe would actually be more appropriate for that usage. The optical quality is very similar and both are excellent loupes. I did not try the Mamiya/Cabin 6×7, unfortunately, as it was not available in the store, but in any case the Rodenstock was a steal.

The optics are excellent, as could be expected, with crisp resolution all the way into the corners and no trace of chromatic aberrations. There is a smidgen of pincushion distortion, however, but not enough to be objectionable (I took the slightly convex curved square skirt out to make sure this was not just an optical illusion).

One thing to watch out for: even though the optics are coated, they are very wide and you have to be careful to keep your eye flush with the eyecup to obscure any overhead light sources like lightbulbs or fluorescent panels and avoid seeing their reflections in the loupe’s glass.

The most comprehensive resource for medium format loupes on the Web is Robert Monaghan’s page on the subject.

Edmunds Hastings triplet

This isn’t really a competitor to the other loupes, as it has a very narrow field of view of only 10mm in diameter. It is also tiny, and I carry mine in my gadget bag. It has a folding jeweler’s loupe design with a folding metallic shield to protect it. Optical quality is of the highest order.

Schneider 10x

Despite its plastic construction, this loupe exudes quality. Unfortunately, the strap is really flimsy – the rubber cord is merely glued into the metal clip, and will easily pull out. I glued mine back, and crimped it with needle-nose pliers for good measure, but I don’t know how robust this arrangement will be.

The optics are excellent, without any trace of chromatic aberration. The usable field of view is surprisingly wide for a loupe with this magnifying power, although your eye has to be perfectly positioned to see it. I estimate the FOV diameter at 20mm, as you can almost see the full height of a 35mm mounted slide. I have an Edmund Optics magnifier resolution chart (it came with the Hastings triplet), and the Schneider outresolves it across the field of view . This means the Schneider exceeds 114 line pairs per millimeter across the frame, quite remarkable performance.

The importance of a good loupe

Golden Gate cable detailFor a real-world test, I took my 6×17 format Velvia 100F slides of the Golden Gate Bridge, and looked at the suspension cables. The picture to the left shows the details I was looking at (but the fuzzy 1200dpi scan on an Epson 3170 does not remotely do justice to the original). Each bundle of 4 cables (4 line pairs) takes 0.04mm on the slide (I used the 50x Edmunds inspection microscope to measure this), hence you need 100lp/mm to resolve it. The Schneider 10x, Edmunds 10x and Zeiss 5x loupes all resolve the four cables clearly. My old el cheapo Peak 10x loupe did not, nor the Epson scanner, which led me until recently to believe my slides were slightly blurry because I had forgotten my cable release that day. So much for the theory you do not need an expensive 10x loupe to assess critical focus because only the center counts…

Update (2012-02-10):

In 2007 I added a Calumet-branded 4x Rodenstock aspheric loupe to my collection. Unfortunately, it is now only available under the original brand, for 2.5x the price I paid for the rebranded one, but you may luck out and find old-new stock at you local Calumet Photo store. The market for loupes has mostly evaporated, along with the popularity of film, and choices today are pretty much limited to Schneider and Rodenstock.

The Rodenstock 4x loupe has one great ergonomic feature: instead of interchangeable clear and dark screw-in skirts, it has a clear skirt and a sliding dark outer skirt. This allows you to switch very quickly from inspecting prints to slides, without the laborious swap the Schneider or Zeiss force you into. Optically it is excellent, sharp across the field and with only a smidgen of pincushion distortion. I have not tried the 4x Schneider loupe, which gets rave reviews, and cannot comment on whether the ergonomic improvement in the Rodenstock warrants a 50% premium in street price over the Schneider.

One loupe I cannot recommend, on the other hand, is the Leica 4x magnifier. It has severe distortion across the field, which is ridiculously limited at 3 or 4mm, and optical quality is worse than a cheapo plastic loupe from Peak.

Update (2012-02-25):

I added a Schneider 4x loupe to my collection. Build quality and strap is similar to their 10x loupe. It is sharp across the entire frame, with only a smidgen of pincushion distortion. It is also noticeably brighter than the Zeiss Triotar or the Rodenstock 4x, and has more contrast as well. The contrast makes it seem superficially sharper than the Zeiss or Rodenstock, but examination of the Edmunds test chart shows all three loupes outresolve the chart.

I think this will be my new favorite loupe for 35mm use.

Threadframe: multithreaded stack frame extraction for Python

Note: threadframe is obsolete. Python 2.5 and later include a function sys._current_frames() that does the same thing. Threadframe is only useful for Python 2.2 through 2.4.


I was encountering deadlocks in a multi-threaded CORBA server (implemented using omniORB). Debugging using GDB gave me too low-level information, and what I needed was an equivalent of the GDB command “info threads”. There was no such facility available from within Python’s standard library, so I rolled my own.

David Beazley added advanced debugging functions to the Python interpreter, and they have been folded into the 2.2 release.

I used these hooks to build a debugging module that is useful when you are looking for deadlocks in a multithreaded application. It basically has a single function that will return a list of the stack frames for all Python interpreter threads in the process.

Guido van Rossum added in Python 2.3 the thread ID to the interpreter state structure, and this allows us to produce a dictionary mapping thread IDs to frames.

This functionality is now integrated in Python 2.5’s batteries-included sys._current_frames() function.

Of course, I disclaim any liability if this code should crash your system, erase your homework, eat your dog (who also ate your homework) or otherwise have any undesirable effect.

Building and installing

Python 2.2 or later is required. Thread ID to frame dictionary extraction is only available in Python 2.3 and later, and will generate a NotImplementedError if used from 2.2.

Download the source tarball threadframe-0.2.tar.gz. You can use the Makefile or directly with the script. I have built and tested this only on Solaris 8/x86 and Windows 2000, but the code should be pretty portable. There is a small test program that illustrates how to use this module to dump stack frames of all the Python interpreter threads. A sample run is available for your perusal.

For Windows users, I have available pre-compiled binaries, built using Mingw32 and GCC 2.95.2. Just copy the file threadframe.pyd in any location in your Python path and you should be able to run the test script

Windows binaries
Python versionDownload
2.2.1 threadframe.pyd
2.3.4 threadframe.pyd
2.4.x threadframe.pyd


This code is licensed under the same terms as Python itself.

Change history

Release 0.2 (2004-06-10)

Distutils based contributed by Bob Ippolito. Bob also noticed that thread_id was added to the Python interpreter state, and contributed a patch to get a dictionary mapping thread_ids to frames instead of a list.

Release 0.1 (2002-10-11)

Initial release for Python 2.2: threadframe-0.1.tar.gz

The Temboz RSS aggregator

2013-03-14: Google’s announcement that their Reader service will be discontinued has spurred interest in Temboz. This software is not dead, in fact I use it daily, but have not made an official release in a long time. You should use the version from Github instead. There are currently a number of bugs which can lead to Temboz locking up and requiring a restart. I am planning on completing my long overdue overhaul before Google’s July deadline.



Temboz is a RSS aggregator. It is inspired by FeedOnFeeds (web-based personal aggregator), Google News (two column layout) and TiVo (thumbs up and down). I have been using FeedOnFeeds for some time now, but that software seems to have stopped evolving, and I had a number of optimizations to the user experience I wanted to make.


Already implemented:

  • Multithreaded, download feeds in parallel.
  • Built-in web server.
  • Two-column user interface for better readability and information density. Automatic reflow using CSS.
  • Ratings system for articles
  • Real-time hunter-gatherer user interface: items flagged with a “Thumbs down” disappear immediately off the screen (using Dynamic HTML), making room for new articles. No laborious flagging of items as in FeedOnFeeds.
  • Filtering entries (using Python syntax, e.g. ‘Salon’ in feed_title and title == “King Kaufman’s Sports Daily”, or simply by selecting keywords/phrases and hitting “Thumbs down”).
  • Ability to generate a RSS feeds from “Thumbs Up” articles, which is why Temboz would be a true aggregator, not just a reader.
  • Ad filtering
  • Automatic garbage collection: every day between 3AM and 4AM, uninteresting articles (by default those older than 7 days) are purged of their contents (but not metadata such as titles, permalinks or timestamps) to keep the database size manageable. After 6 months (by default), they are deleted altogether
  • Automatic database backups daily (immediately after garbage collection)

On the to do list:

  • Write better documentation
  • Handle permanent HTTP redirects for feed XML URLs
  • Automatic pacing of feed polling intervals using the average and standard deviation of observed feed item inter-arrival times, to reduce bandwidth usage and load for both client and server. Most feeds should be polled on a daily rather than hourly interval (e.g. my own, since I update once a week on average), but the mechanisms for a feed to indicate its polling rate preferences are quite inconsistent from one flavor of RSS/Atom to another.
  • “Survivor mode” – vote feeds that no longer perform off the aggregator based on relevance statistics.
  • Ability to cluster together articles (I tried a heuristic of looking for common URLs they are all pointing to, but this didn’t work well in practice).
  • Portability to Windows, distribution as a standalone package.


I have been using it successfully for well over a year. It still has rough edges, with some administration functions only doable using the SQLite command-line utility. Here is a screen shot showing the reader user interface. The article highlighted in yellow was given a “Thumbs Up”. You can also see the user interface at work in a view of the last 50 articles I flagged as “thumbs up” among the feeds I read.

Screen shots

Click on a screen shot thumbnail for a full-sized version

The first screen shot shows the article reading interface, using a two-column layout. Clicking on the “Thumbs down” icon makes the article disappear, bringing a new one in its place (if available). Clicking on the “Thumbs up” icon highlights it in yello and flags it as interesting in the database.

view itemsThe feed summary page shows statistics on feeds, starting with feeds with unread articles, then by alphabetical order. Feeds can be sorted based on other metrics. You have the option of “catching up” with a feed (marking all the articles as read). Feeds with errors are highlighted in red (not shown).

view feedsClicking on the “details” link for a feed brings this page, which allows you to change title or feed URL, and shows the RSS or Atom fields accessible for filtering.

feed detailsFeeds can be filtered using Python expressions.

filtering rules

Known bugs

You can check outstanding bug reports, change requests and more at the public CVStrac site.


Temboz is written in Python, and leverages Mark Pilgrim’s Ultra-liberal feed parser, SQLite 2.x, Cheetah.


You can download the current version: temboz-0.8.tar.gz I welcome any feedback you may have, specially as concerns improving installation.

The CVS version is far ahead of 0.8 in features. I have not yet had the time to test and document the migration procedure from 0.8 to 1.0, but if you are a new Temboz user I strongly advise you to get a nightly CVS snapshot instead (they are what I run on my own server): temboz-CVS.tar.gz or


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Temboz has a CVStrac where you can submit bug reports or change requests, and a Wiki, where all future documentation will ultimately reside.

Post scriptum

The name “Temboz” is a reference to Malima Temboz, “The mountain that walks”, an elephant whose tormented spirit is the object of Mike Resnick’s excellent SF novel, Ivory.