Kategorie-Archiv: Development

A link to your Call for Papers

You have an upcoming conference for which you run a Call for Papers (CfP)? Then why not let everyone know by adding a link to where we can find more informations?

Something like the following could be parsed automatically and would allow easier finding of your CfP:

<link rel="cfp" href="[Link to your CfP-page]" data-closes="[ISO-Date of the end of the CfP]"/>

This could then look like this:

<link rel="cfp" href="https://example.com/cfp" data-closes="2015-12-24 12:00:00+02:00" />

That way websites displaying CfPs could fetch the information that there is a CfP from your main website and you would not need to provide extra informations about a CfP on a different place.

And while we’re at it: Your Event surely has a geographical location, so why not add that one via the following resource?

<link rel="venue" href="geo:[latitude],[longitude]"/>

It uses a geo-URI as specified in RFC5870 and can therefore also been read automatically to check for the venue of your event.

Alternatively you can include information about your event or the location using metadata as defined by schema.org. That way you can add even more informations about your event or the location than using a simple link. Thanks to Jurian Sluiman for reminding me!

Database-Testing with PHPUnit and sqlite

Today I wanted to test a database-handling class using PHPUnits PHPUnit_Extensions_Database_TestCase and an sqlite in-memory database.

On running the tests I always got the following error-messages:

MyDatabaseTest::testDatabaseConnection with data set #0 ()
PHPUnit_Extensions_Database_Operation_Exception: COMPOSITE[TRUNCATE] operation failed on query:
                DELETE FROM "[tablename]"
             using args: Array
 [SQLSTATE[HY000]: General error: 1 no such table: [tablename]]


After some checking what might help I got different solutions:

  • Use MySQL as test-backend – No, I want to use an sqlite with in-memory storage as it’s fast and doesn’t require too much setup on a CI-Server
  • Use a pre-configured sqlite-file and therefore a file-based sqlite. That might have been possible, but I just wanted to use in-memory….

The solution was rather simple. It seems that PHPUnit deletes the content of the table in question before setting up the table to execute a test. That only works, if the table already exists. Therefore I’ve added a create table xyz statement right after setting up the in-memory-table. So the test-class now looks like that:

class MyDatabaseTest extends PHPUnit_Extensions_Database_TestCase
    protected $pdo = null;

     * @return PHPUnit_Extensions_Database_DB_IDatabaseConnection
    public function getConnection()
        if (null === $this->pdo) {
            $this->pdo = new PDO('sqlite::memory:');
            $this->pdo->exec('create table [tablename]([table-definition])');
        return $this->createDefaultDBConnection($this->pdo, ':memory:');

     * @return PHPUnit_Extensions_Database_DataSet_IDataSet
    public function getDataSet()
        return $this->createXMLDataSet('[path/to/xml-seed-file]');

    public function testDatabaseConnection()
        $pdo = $this->getConnection()->getConnection();
        // Do your database-tests here using the required pdo-object

Perhaps this can help someone to find a solution earlier 😉

Displaying Date-Ranges

Recently a new issue popped up on the joind.in issue-tracker which called for nicer date-ranges. As I did something like that a few weeks prior I grabbed the issue and starded working.

The output is a small library that enables you to display a date-range like 12. – 13. March 2015 instead of 12. March 2015 – 13. March 2015.

Simple thing.

It also displays March 12th – March 13th 2015 if you want to.

Not that easy any more.

I won’t bother you with the details on how it’s done (it seemed more difficult than it actually was) as you can see that in the source-code if you are interested.

Displaying Date-Ranges weiterlesen

New and cool features in PHP5.6

PHP5.6 is, at the date of writing this, in the first beta phase. So the good question is: What new and cool features can we expect in the shiny new PHP-Version?

  • Exponential operator
  • importing namespaced functions
  • constant scalar expressions
  • variadic functions
  • argument unpacking
  • phpdbg
  • Streams for POST-data
  • Default Character-Encoding improvements
  • TLS improvements
  • More „under-the-hood“-Improvements

For a full list of changes have a look at the RFC-Part of the php.net wiki

New and cool features in PHP5.6 weiterlesen

Create signed PDF-Files

Some days ago a friend of mine asked me how to create PDF-Receipts. Background is that – at least in Germany – you can replace printed receipts with digitally signed PDF-Files. The signature has to comply to certain legal standards to be able to replace the printed copy but the way is the same whether it’s a self-signed certificate or an official one.

For the start I wanted to see how to sign a PDF-Document created with TCPDF. At a later time I will also have a look at how to sign a PDF-File using the libraries supported by PDFlib.com.

Signing PDF-files with TCPDF requires you to have the private key and the certificate available via a stream-ressource. That excludes certificates and keys on a signature-card as long as you can not export them.

Creating a signed PDF-File using TCPDF is rather simple as you can see in this code-snippet:


// set certificate file
$certificate = 'file://' . __DIR__ . '/cert/certificate.crt';
$privateKey = 'file://' . __DIR__ . '/cert/privateKey.crt';
// set document signature
$pdf->setSignature($certificate, $privateKey, 'test1234', '', 1, array());

// Do some more stuff here like creating the actual PDF-File

//Close and output PDF document
$pdf->output('test.pdf', 'D');

That’s it.

The hard part now is for one thing creating the actual PDF-File.
And the more important one question was „Which certificate-key-thingy goes where“.

That was the one that took me most of the time. When using a self-signed certificate as described in the TCPDF-Example you can somehow use the given openSSL shell-lines to get somehow to a result. But I wanted to sign the document with a „qualified electonical signature“ which takes some more steps.

What is a qualified electronical signature? It’S nothing else than any other digital signature from a certification authority. The only difference is, that it has been issued according to the german „Signaturgesetz“ which means, that it is based on a qualified certificate and has been created using a certain approved PKI. As I am not a lawyer, this is simply my own description of a legal process which might be inaccurate or plain false. So do not take my word as legally authoritative. A list of issuers for qualified electronical signatures can be found at http://www.nrca-ds.de/ZDAliste.htm

As I do not posses such a qualified electronical signature (and there currently is no need for me to get one) I tried the whole stuff with a certificate I got myself from CA-Cert. As far as I know (but I will verify that one soon) you can export a qualified electronic signature into a format that can be used for these purposes.

The relevant parts are the following variables

needs to point to a certificate file in PEM-Format. Thats a plaintext-file with —–BEGIN CERTIFICATE—– and —–END CERTIFICATE—– and some base64 encoded stuff in between.
needs to point to a private key file in binary PKCS7-Format. Those files normally end in something like ‚.p12‘ or ‚.pfx‘. To open this file you normally need a passphrase which you have to provide as third parameter to $pdf->setSignature.

Using that certificate and private key you can now sign your PDF-file.