Sunday, 22 March 2020

Improvements to free sitemap visualiser

SiteViz is as its name suggests, a tool for visualising a sitemap.

Integrity Plus, Pro and Scrutiny can export their sitemap data in the form of a .dot file, which contains the information necessary to draw a chart.

Early on, Omnigraffle did a great job of displaying these .dot files but it became expensive. There were other options but nothing free and easy to use. That's where SiteViz came in and its functionality has been built into Scrutiny.

Its default chart didn't look great though. The layout was flawed making the charts less than ideal.

Version 3 contains some vast improvements to that 'bubble tree' theme, along with some improvements to the colouring. Nodes can be coloured according to links in or 'link juice'. (Think liquid flowing through your links). Connections can be coloured according to multiple criteria too. The charts now look much more professional and are much more useful, especially the bubble tree theme. The screenshots you see on this page were made using it.

It will remain a free viewer. You can export the chart as a png image or pdf, but it can't create the .dot sitemap. For that you'll need a website crawler like Integrity Plus or Pro.

Thursday, 19 March 2020

What happens in Objective C if you compare two NSObjects with a simple 'greater than' or 'less than'?

This is one of those odd bugs that goes unnoticed because a line of code that shouldn't work,  strangely does, at least most of the time.

The problem exhibited itself under certain circumstances. That led me to investigate and discover this line (in pseudocode):

if ([object getProperty] > [anotherObject getProperty]){

Years ago, this line was correct, because in this particular object's getProperty used to return a primitive such as an int or NSInteger (I can't remember which).

But at some point getProperty was changed so that it returned an NSNumber, which is an object rather than a simple value.

The line should have been updated to (and has been now):

if ([[object getProperty] integerValue] > [[anotherObject getProperty] integerValue]){

Of course I should have searched the source for 'getProperty' and updated accordingly but this particular line escaped. It went unnoticed. The compiler didn't complain, and everything still seemed to work.

If a tree falls in a forest......    If a bad line of code appears to work under testing and no-one reports a problem, is it still a bug?

It didn't always work though. Under certain circumstances that particular thing went screwy (no crash, no exception, just odd results sometimes). But not randomly. It worked or didn't work predictably, depending on the circumstances.

I can't find confirmation of this but it seems from what I've observed that

(NSObject > NSObject) 

returns true or false depending on the order that they were created. I'm assuming that the comparison is being made using the object's address (pointer) treated as a numeric value. This makes sense because declaring NSObject *myobject  declares myobject as a pointer, which is some kind of primitive, known to contain a memory address.

A simple experiment seems to bear this out.

    NSNumber *number1 = [NSNumber numberWithInt:2];
    NSNumber *number2 = [NSNumber numberWithInt:10];
   
    NSLog(@"number1: %p, number2: %p", number1, number2);
   
    if(number1 > number2){
        NSLog(@"number1 is greater than number2");
    }
    else{
        NSLog(@"number2 is greater than number1");
    }

returns:

NumberTest[89819:23978762] number1: 0x7312659ea1d74f79, number2: 0x7312659ea1d74779
NumberTest[89819:23978762] number1 is greater than number2

It's interesting that the objects seem to be allocated going backwards in memory in this example. I assume that allocation of memory is not predictable, but that there would be some general sequence to it, backwards or forwards.


I'm obviously pleased to have found and fixed a problem in this app. But more than anything this has amused and interested me.

If you have anything to contribute on this subject, leave it in the comments.

Monday, 16 March 2020

scraping email addresses with WebScraper

This has been a popular question from Webscraper users.

It has already been possible to use WebScraper to scrape email addresses with some caveats. a/ It required setting up, using your favourite regular expression for matching email addresses (these are easy to find online if you're not a regex demon) and b/ it'll only work if the email addresses appear unobfuscated in the source or visible text. It has long been popular to use some method of hiding email addresses from bots.

To help with this particular task, you can now set up WebScraper more easily (as from version 4.11.0).  'Email Addresses' now appears in the drop-down buttons for the simple and complex setups.

Here's the simple setup. It couldn't be easier; 'Email Addresses' appears in the second drop-down if you choose 'Content' in the first. Skip to the Post-processing tab  >>

Output file columns

For the complex setup, by default you get the URL and Title columns by default. You may like to keep those so that you can see which page each email address appears on.  Or delete them if you simply want a list of email addresses. Then add a column. As with the simple setup, choose Content and then Email Addresses.

Results tab

At this point (After running the scan or a test) each page is presented on a row of this table. If there are multiple email addresses on a page, they'll be  listed in a single cell separated by a pipe. We'll fix that later. There may also be big gaps where pages don't contain an email address. That's also something we can fix.

During the scan, at the point where email addresses are scraped from a page, the results are uniqued. So if the same address appears multiple times on the same page (which is likely if the address appears as a link - it may be in the link and in the visible text) then it'll only appear once in that row on the Results tab.

Post-processing tab

Here's where we can tidy up the output. The first checkbox will split multiple results onto separate rows. The third checkbox will skip rows where there are no results. The drop-down button will contain a list of your output columns, choose your email address column. As the label says, these things will be done when you export your output to csv.

Preferences

The default expression used for this task will match strings like xxxx@xxxx.xxx  I found that this can match certain images that have an @ symbol in their filename. If you wish to improve the regular expression, then simply change it in this field in Preferences.

Export

Here's my output for this example (I chose not to include the url and title columns). Note that the same address appears a lot. At time of writing WebScraper doesn't have a 'unique' option on the post-processing tab but that's under consideration. Also note that caveat b at the top of this article still applies.



Tuesday, 10 March 2020

Changes to nofollow links : sponsored and ugc attributes : how to check your links

Google announced changes last year to the way they'd like publishers to mark nofollow links.

The rel attribute can also contain 'sponsored' or 'ugc' to indicate paid links and user-generated content. A while ago, nofollow links were not used for indexing or ranking purposes. But this is changing. Google will no longer treat them as a strict instruction to not follow or index.

This article on moz.com lists the changes and how these affect you.

As from version 9.5.6 of Integrity (including Integrity Plus and Pro) and version 9.5.7 of Scrutiny, These apps allow you to see and sort your links according to these attributes.

There was already a column in the links views for 'rel' which displayed the content of the rel attribute, and a column for 'nofollow' which displayed 'yes' or 'no' as appropriate. Now there are new columns for 'sponsored' and 'ugc' (also displaying yes/no for easy sorting). Many of the views have a 'column' selector . If visible, these columns will be sortable and they'll be included in csv exports.


Tuesday, 4 February 2020

How to extract a table from html and save to csv (web to spreadsheet)

WebScraper users have sometimes asked about extracting data contained in tables on multiple pages.

Tables on multiple pages


That's fine if the table is for layout, or if there's just one bit of info that you want to grab from each, identifiable using a class or id.

But to take the whole table raises some questions - how do you map the web table to your output file? It may work if you can identify a similar table on all pages (matching columns) so that each one can be appended and match up, and if the first row is always headings (or marked up as th) and can be ignored, except for maybe the first one.

It's a scenario with a lot of ifs and buts, which means that it may be one of those problems that's best dealt on a case-by-case basis rather than trying to make a configurable app handle it. (if you do have this requirement, please do get in touch.)

Table from a single page


But this week someone asked about extracting a table from a single web page. It's pretty simple to copy the source from the web page, paste it into an online tool, or copy the table from the web page and paste into a spreadsheet app like Numbers or Excel and that was my answer.

But this set me thinking about the job of parsing html and extracting the table data ready for saving in whatever format.

At the core of this is a cocoa class for parsing the html and extracting the table (or tables if there are more than one on the page). With a view to possibly building this into WebScraper to allow it to do the 'tables on multiple pages' task, or for having this ready, should the need arise to use this in a custom app for a one-off job, I've now written that parser and built a small free app around it.

That app is the imaginatively-titled HTMLTabletoCSV which is now available here.


Wednesday, 29 January 2020

Upgrading the hard disk in a G4 iMac

I bought this iMac new in 2003 and used it as my main machine for some time. I was writing software at the time, had a number of products out, but it wasn't my full-time business then. Eventually it was packed away to make room for newer machines.
Isn't it beautiful? OSX 10.4 is a really great version of the operating system, and this is the time when iTunes was at its height. I'd long had it in mind that it would make a great jukebox for kitchen or bedroom, with its great Harmon Kardon speakers with optional subwoofer. 

To be useful again, mine needed:
  • Wireless card (I never did fit one)
  • Hard drive upgrade* (the standard 80Gb one isn't big enough for half of my music collection)
  • Replacement CD drive** (mine had broken somewhere along the line)
  • New battery (small alkaline battery for keeping the time and date)
[Edit] since first writing this post, I've also added:
  • a set of JBL Creature speakers 
  • 1Gb RAM

The parts I expected to be hard were easy, and the parts that should have been easy were hard. I'm documenting my experiences here because there are some things that may be useful to others.

I'd already collected some of these parts, intending to do the work one day. Last week something reminded me of Cro-Mag Rally. It's a great game and the Mac version is now free, thank you Pangea. The OSX version needs a PowerPC mac, and my clamshell iBook proved too slow. so out came the G4 iMac.
 It wasn't remembering the time, which of course means that the battery is dead, and a battery inside an almost 20-year old computer is bad news. So perhaps the time was right to carry out those other upgrades at the same time.
The wireless card and adding RAM are pretty much a trapdoor job (well, behind the stainless steel cover, which has 4 captive crosshead screws. Very simple.) No worries if that's all you have to do.

NB, 10.4 (Tiger) allows connection with WPA2, which is what I needed at home. and the Airport Extreme is working fine. 10.3 and earlier don't have the WPA options, only WEP. Whether those earlier systems can be made to work with a modern router, I can't say.
I had to go deeper. You need to go one layer further even to replace that battery.  This is the new hard drive and replacement CD drive. The latter came from an eBay seller, used but working (allegedly). The HD and my new battery are from the BookYard, I recommend them (as a UK buyer), their website makes it easy find the right parts for your particular machine. The service was efficient and swift.
I have read that delving more deeply into the machine is an advanced task and I was expecting it to be harder than it really was. It's actually very simple. I'm not going to give instructions, there are plenty elsewhere. That's the old CD/HD assembly coming out, note the horrible amount of dust in there. With those out, it's possible to vacuum out the fan and all of the nooks and crannies, taking anti-static precautions.

One point of uncertainty for me was about the jumper settings for the new HD and CD drives. The replacement CD came with a single ribbon cable with a 'tap' halfway for the HD. The existing ones each had their own cables (there are two sockets on my board). I suspect that the CD drive came from a different model (there are several variations and three with 17" screens - 800Ghz, 1Ghz and 1.25Ghz.) Besides the difference with the cable, the little metal screen at the front was slightly different and I had to nab the that part from the old old drive.

Back to the jumper settings. The replacement CD drive came jumpered as a slave, which may be consistent with it being on the same ribbon cable as its HD. With my existing drives, each had their own cable and each was jumpered for 'cable select'. I decided to use my existing cables and jumper both drives for cable select as before. That worked.

NB - if you're going further than the trapdoor, there's some thermal paste that you must clean up and apply new. See the iFixit article for details.

 There's the replacement battery in and with everything back together, it chimed and as expected there's the icon for 'no startup volume'.
This is where the games really started. The new CD drive worked and I expected it to be easy to make a fresh OS install on the new blank drive, but I had a very frustrating time.

I have numerous discs from various computers. However, not all were readable and some were upgrade discs rather than install. Those that I downloaded from the web and burned to CD were either not bootable or simply would not boot. (If you're reading this and know why, please leave the answer in the comments.)

I still had the drive that I'd taken out, and 'restoring' or cloning an existing volume to a new one should be very easy using Disk Utility, which comes on every system and every bootable install disc.

At first I opened up the computer again and plugged in the old drive in the CD drive's socket on the motherboard. This worked, I could boot from it and perform the 'restore'.

However, it didn't work first time - the clone on the new drive wouldn't boot. I had to try again and again. Because my first method was a little makeshift, I devised this - it's a firewire  'caddy' made from an old LaCie firewire hard drive. I opened it up, unplugged its own HD and plugged in my computer's HD and voila! It plugs into the reassembled computer and can boot the computer (you can boot from a firewire external drive but not a USB one).
The old drive had three different versions of OSX installed on different partitions. Back in the day this allowed me to boot into  OSX 10.2, 10.3 or 10.4. Very useful for testing my software.

My first attempts at cloning the 10.4 partition failed a couple of times. The first time I thought it was because I hadn't checked 'erase' before doing the copy. But I don't know why the second attempt wasn't successful.

I'd read mixed opinions about the maximum size for the boot volume with this machine. I thought this might be the problem for a little while but I can tell you that I have a 500GB drive with a single partition / volume, and that it now boots.

For my final attempt I tried booting into 10.3 (Panther) and using its version of Disk Utility. (This I think being the system that came with the machine). I don't know whether this made the difference, or whether it was because I reformatted the new drive at that point. (It had come apparently formatted, so I hadn't bothered before). That new clone of the 10.3 volume did successfully boot. After that I successfully used an upgrade disc to take it to 10.4, and then a multipart update downloaded from the Apple developer site to take it to 10.4.11

Now I have a mac with a system that really doesn't feel out of date, a version of iTunes (7) which is a joy to use, a 500GB drive, wireless (10.4 allows me to connect with WPA2). A useful and usable machine, and one which looks amazing.

[edit]

I've now added 1Gb RAM. This is very cheap now, and keeps it responsive. Tiger is a newer system than the one the machine came with. I was starting to get lack of responsiveness with very little running.

I've also added these 'Creature' speakers. They were sold as 'made for mac' when the G4 was sold new. I really wanted a white set, but this set was an absolute bargain. Replacing the drivers in the satellites is another story. The original speaker cones are destined to disintegrate, and these ones had. Now that I've replaced them I'm not entirely happy. I'll live with these for a while. I will probably get a broken but nice-looking white set in the future, and repair the little speakers with better replacement drivers.




* Why not a SSD? I had intended to do this for some time. But a ATA/IDE/PATA  SSD isn't so easy to find, and I read that the limitations of the ATA system mean that the speed benefit is lost. A brand new spinning disc is cheaper and still quiet. So that's what I went for.
** I refer to the drive as a CD drive in this post. Actually it's a combined CD reader / writer and DVD reader, known as a 'superdrive'.

Tuesday, 31 December 2019

Finding mixed / insecure website content using Scrutiny

It's been a while since some browsers have been warning that a page is insecure. I read recently that Google Chrome will start blocking HTTP resources in HTTPS pages.

If you've not yet migrated your website to https:// then you're probably thinking about doing it now.

Once the certificate is installed (which I won't go into) then you must weed out links to your http:// pages and pages that have 'mixed' or 'insecure' content, ie references to images, css, js and other files which are http://.

Scrutiny makes it easy to find these.

If you're not a Mac user or you'd simply like me to do it for you, I'm able to supply a mixed content report for a modest one-off price. It will list

  • pages with links to internal http: pages
  • pages which use resources (images, style sheets, etc) which are http
  • https:// pages which have a canonical which is http://
  • https:// urls which redirect to a http:// url


If you're interested in using Scrutiny to do this yourself, read on.

1. Find links to http pages and pages with insecure content.

First you have to give Scrutiny your https:// address as your starting url, and make sure that these two boxes are ticked in your site-specific settings,

and these two as well,

After running a scan, Scrutiny will offer to show you these issues,

You'll have to fix-and-rescan until there's nothing reported. (When you make certain fixes, that may reveal new pages to Scrutiny for testing).

2. Fix broken links and images

Once those are fixed, there may be some broken links and broken images to fix too (I was copying stuff onto a new server and trying to only copy what was needed. There are inevitably things that you miss...) Scrutiny will report these and make them easy to find.

3. Submit to Google.

Scrutiny can also generate the xml sitemap for you, listing your new pages (and images and pdf files too if you want).

Apparently Google treats the https:// version of your site as a separate 'property' in its Search Console (was Google Webmaster Tools). So you'll have to add the https:// site as a new property and upload the new sitemap.

4. Redirect

As part of the migration process, Google recommends that you then "Redirect your users and search engines to the HTTPS page or resource with server-side 301 HTTP redirects"  (full article here)