In some situations it is necessary to hide binary data in another file format so that it cannot be easily detected — be it to store data on image storage platforms such as Picasa, or to circumvent firewalls or mail filters. I wrote a little helper to encode byte arrays, streams or files into 24-bit bitmap images (BMP files).
I recently built myself a new and shiny HTPC for my living room, and because it took lots of time researching the right components, I’d like to share my experiences. I published this post first on the XBMC forum a couple of days ago. Feel free to comment either here or there. Lots of pictures in the post!
Some of AVM’s Fritz!Box routers allow connecting a USB device and use this device as a network attached storage (NAS) via Samba/SMB in the local network. In combination with the fact that the NAS can also be accessed from the Internet via FTP, and the multimedia files can be streamed to a TV via the Fritz!Mediaserver (using DLNA), it makes a pretty basic home entertainment system. I use it to automatically copy videos (YouTube, etc.) to the NAS from my virtual server, and then watch these with my Samsung Smart TV. It’s not as great as XBMC, but it works for now.
Unfortunately, the Fritz!Mediaserver (DLNA server) does not automatically refresh the index when media files are added via Samba/SMB or FTP (only if they are added via their web interface Fritz!NAS). It can be refreshed manually via the interface on fritz.box/storage/settings.lua. But, since I like to automate things, I made a little helper to automatically refresh the index.
Many of the well known websites determine your location based on your IP address and restrict their content or functionalities based on the country you’re in. Some examples are Gmail (Germans get only @googlemail.com-addresses, legal reasons), YouTube (content is restricted by the GEMA), and Pandora (limited to US citizens) to name only a few. To circumvent these restrictions, being able to quickly get an IP address outside of your own country is most helpful.
To do exactly that I wrote a little script that will start your very own US proxy server in one minute using Amazon EC2. In combination with browser plug-ins such as FoxyProxy, the script enables you to route all your web traffic through a proxy on an Amazon-owned machine — with an IP address in the US, Ireland, Singapore, Tokyo or Sao Paulo (location of Amazon data centers).
I recently wrote my first little app for my Android smartphone and I was surprised how easy it was. Being familiar with regular Java, learning the new Android APIs was very simple for the most part. However, there was one thing that wasn’t particularly straight forward: communicating between an Activity, i.e. the user interface, and a background Service started by the application. After many hours, I found some sample code on Stack Overflow which I used to create a very generic reusable solution to start, stop and communicate with your own Service implementation.
Adobe’s proprietary Flash format has become a significant part of the Internet as it is today. While its importance in Web applications is slowly decreasing due to Web 2.0 technologies and HTML5, it is still a major player in the browser game and application sector. The majority of these games and applications are for entertainment only and offer you nothing but a nice rank in the high score. On rare occasions, however, there are Flash games in which you can actually win something valuable such as concert tickets or even money. And of course there are applications that let you stream, but not download content from a website.
So what’s the problem with that, you think? The problem is that almost all Flash applications can be hacked very easily and most developers are not aware of that.
As a reminder of how vulnerable Flash applications are, this post aims to raise awareness for these issues. In a case study, it shows how a Flash-based game and its server side high score can be tricked within a few minutes using free tools only.
Version control systems like CVS or Subversion are designed for keeping track of the changes of a project and for having the possibility to revert to old revisions if something goes wrong. In contrast to regular relational databases, these systems are made only for adding new content to a repository, and not for removing data from it. In fact, deleting old content is not a built-in functionality in SVN, and mostly requires removing entire revisions from the repository or even creating a new one.
But what happens if you accidentally commit a password or other sensitive information to a repository? This post explains how to remove this confidential data permanently from the repository by simply overwriting it in old revisions, i.e. without having to remove revisions or create a new repository.
As one of the best picture organizers out there, Picasa is (in my opinion) almost complete in terms of features and has a nice look and feel at the same time. Even though Google stopped developing the Linux version after 3.0, it still works perfectly using Wine and a couple of cp-statements.
However, as stated many times by Picasa users and bloggers [1,2,3,…], Picasa’s export function misses a tiny little feature that maintains the sort order of the album when exporting it to a folder. Instead of renaming the pictures to keep them sorted in normal file managers (by name), Picasa just copies the files of an album to one folder and thereby destroys the order. As if that wasn’t enough, Picasa also overwrites duplicates filenames from different source folders.
This missing feature has even led to small standalone projects that fix this issue, e.g. Picasa Independent Album Exporter (PIAE) and Picasa Order Preserver. While both applications do their job, both are a bit heavyweight, and PIAE only works for Windows (and not on Wine).
This post presents a tiny little Perl script that renames pictures of an exported album according to their Picasa sort order.
The capabilities of cell phones increased dramatically in the last few years. While in the old days most mobile phones were primarily used to make phone calls, modern smart-phones are mostly all-round devices. With the possibility of accessing the Internet and the availability of various sensors (e.g. location or noise), mobile applications have become interactive and flexible. The trend towards location-based services and context-awareness allows applications to react on their surroundings and to behave intuitively towards the user.
For developers, context-awareness can be both a blessing and a curse. While the mobile operating systems iPhone OS and Android come with relatively good sensor-support, the vast majority of devices deal with Java ME’s basic and heterogeneous sensor functionalities.
The Aware Context API (ACAPI) aims to bridge this gap by providing a framework for building context aware applications for mobile devices based on Java ME. In this article, I’d like to introduce ACAPI, its structure and usage briefly. Please feel free to comment.
In the last few years, the importance of the Internet has risen constantly and made it indispensable for businesses and most individuals to be on-line around the clock. One of the greatest drivers of this development was and still is the shift of the traditional one-to-many Web to an advanced, participatory version of the Word Wide Web. Rather than only making editorial information accessible to many users, the Web 2.0 encourages participation and enables user generated contributions. Leveraging this new paradigm, services like Flickr, Facebook, or Twitter have become very prominent examples for this development.
An essential part of this evolution, but mostly hidden to the end-consumer, is the set of tools that enable these large scale applications. Cloud computing is a relatively new technology that serves as underlying architecture for most of these platforms. By providing virtualized computing resources as a service in a pay-as-you-go manner, cloud computing enables new business models and cost effective resource usage. Instead of having to maintain their own data center, companies can concentrate on their core business and purchase resources when needed. Especially when combining a privately maintained virtual infrastructure with publicly accessible clouds in a hybrid cloud, the technology can open up new opportunities for businesses and help consolidating resources.
However, since cloud computing is a very new term, there are as many definitions of its components as there are opinions about its usefulness. Most of the corresponding technologies are only a few years old and the toolkits lack of maturity and interoperability.
This article introduces the basic concepts of cloud computing and discusses the technical requirements for setting up a hybrid cloud. It briefly looks into security concerns and outlines the status quo of current cloud technologies. In particular, it evaluates several existing cloud toolkits regarding its requirements, occurring problems and interoperability.