In the company I am I was asked to write an autoupdate function a la chrome. I.e. It should check periodically whether a new version is available, download the new version and apply it silently the next time the application starts.
I already have something up and running but it is more like a dirty hack than something I feel happy about it. So, I would like to know how to design and implement such a solution. My horrible hack works as this:
Have a mechanism to check whether a new version exists (a database query or a web service)
Download a full zip with the whole new version.
Check file signature. If everything went alright, set a registry value: must update to true.
When the application restarts, if the must update value is true, launch an update program and exist.
The update deletes the contents of the application folder, unzips the update and replaces the old contents, launches the application and exits.
Now, I would like to change it, so it works cleaner. I am planning to send the update as a bsdiff file. It gets downloaded. But the question is, what happens next?
When do apply the update?
Who is in charge of applying the patch? is it the program itself or is it a third program, as I did, which is in charge of applying the patch and relaunch the application?
If your going down the C++ route you can go to chromium and download the Chrome source code and dig around to see how the update is done, this might give you a better idea on how to approach it. Here's an article that might help.
If your familiar with .NET the recently release nuget also has an auto update feature that might be useful to look at, you can get the source code from here. David Ebbo has a blog about how its done here.
I'm not up to date on Delphi but you might be able to use either of the above options.
The workflow you proposed is more or less like it should work, but there's no need to re-invent the wheel - there are plenty libraries out there that will do this for you. Using a 3rd party library has the benefit of keeping your code cleaner while making sure the dirty process of auto-update is contained and working flawlessly.
Trust me, I know. I'm the author of NAppUpdate, an app update framework for .NET (which you might want to try out or learn from).
So, after giving it a lot of though, this is what I came with (for active directory I will refer to the directory where the main program lies, active program is the main program and update program is the one that replaces the active program and its resource files):
The active program checks if there is a new version every certain amount of time. If so, download it
Prepare new version in a separate folder (this can be done by copying the contents of the directory with the program to a subdirectory and applying a binary patch, or simply unziping the new version).
Set a flag that indicates that a new version is ready.
When a program is exiting (and one has to control for different interrupts here):
The active program checks the new version ready flag. Launch the update program and exit.
The update program checks if it can write in the active directory. If so, replaces the contents with the prepared version.
The update program has to recheck links and update them accordingly.
So guys, if you have a better workflow, please tell me.
You could literally use the Google Chrome update workflow by using the Google Chrome updater:
http://code.google.com/p/omaha/
They open sourced it Feb 2009.
Related
I really want to inject my C++ program into another (compiled) program. The way I want to do this is changing the first part of bytes (where the program starts) to goto the binary of my program (pasted into an codecave for example) and when it is finished running to goto back where it went before the injected program started running.
Is this is even possible? and if it is, is it a good/smart idea todo so?
Are there other methods of doing so?
For example:
I wrote a program that will write the current time to a file and then terminates, so if i inject it to Internet Explorer and launch it, it will first write its current time to a file and then start Internet Explorer.
In order to do this, you should start reading the documentation for PE files, which you can download at microsoft.
Doing this takes a lot research and experimenting, which is beyond the scope of stackoverflow. You should also be aware that doing this depends heavily on the executable you try to patch. It may work with your version, but most likely not with another version. There are also techniques against this kind of attack. May be built into the executable as well as in the OS.
Is it possible?
Yes. Of course, but it's not trivial.
Is it smart?
Depends on what you do with it. Sometimes it may be the only way.
I am using perl tray from activestate and have a question. I am wanting to make some type of ui or way for a user to set "Settings" on my application. These settings can just be written / read from a text file that is stored on the users computer.
The part I am not understanding though is how to go about making a ui. The only thing i can think of is showing a local perl page that runs on their computer to write to the file. However, I'm not sure how i could get perl to run in the browser when only using perltray.
Any suggestions?
PerlTray is an odd duck. It has an implicit event loop that kicks in after you either fall off the end of your program or after your 1st call to exit(). This makes it incompatible with most other common GUI event loops or most mini-server techniques that operate in the same process & thread.
2 possibilities come to mind:
Most Likely you'll have success spawning a thread or process that creates a traditional perl GUI or a mini-server hosting your configuration web-app. I'd probably pick Tkx, but that's just my preference.
I have a suspicion that the Event Loop used by Win32::GUI may actually be compatible with the event loop in PerlTray, but some experimentation would be required to verify that. I generally avoid Win32::GUI because it's not platform independent, but if you're using PerlTray, you're tied to Windows anyway...
Since MathWorks release a new version of MATLAB every six months, it's a bit of hassle having to set up the latest version each time. What I'd like is an automatic way of configuring MATLAB, to save wasting time on administrative hassle. The sorts of things I usually do when I get a new version are:
Add commonly used directories to the path.
Create some toolbar shortcuts.
Change some GUI preferences.
The first task is easy to accomplish programmatically with addpath and savepath. The next two are not so simple.
Details of shortcuts are stored in the file 'shortcuts.xml' in the folder given by prefdir. My best idea so far is to use one of the XML toolboxes in the MATLAB Central File Exchange to read in this file, add some shortcut details and write them back to file. This seems like quite a lot of effort, and that usually means I've missed an existing utility function. Is there an easier way of (programmatically) adding shortcuts?
Changing the GUI preferences seems even trickier. preferences just opens the GUI preference editor (equivalent to File -> Preferences); setpref doesn't seems to cover GUI options.
The GUI preferences are stored in matlab.prf (again in prefdir); this time in traditional name=value config style. I could try overwriting values in this directly, but it isn't always clear what each line does, or how much the names differ between releases, or how broken MATLAB will be if this file contains dodgy values. I realise that this is a long shot, but are the contents of matlab.prf documented anywhere? Or is there a better way of configuring the GUI?
For extra credit, how do you set up your copy of MATLAB? Are there any other tweaks I've missed, that it is possible to alter via a script?
shortcuts - read here and here
preferences - read http://undocumentedmatlab.com/blog/changing-system-preferences-programmatically/
At the moment, I'm not using scripts, though this sounds like a very interesting idea.
Unless there are new features that you also want to configure, you can simply copy-paste the old preferences into the new prefdir. I guess this should be doable programmatically, though you might have to select the old prefdir via uigetdir. So far, this has not created major problems for me. Note also that in case of a major change in the structure of preferences, any programmatic version would have to be rewritten as well.
I'm adding paths at each startup, so that I don't need to think of manually adding new directories every time I change something in my code base (and I don't want to have to update directory structures for each user). Thus, I also need to copy-paste startup.m for each installation.
If I had to do everything manually, I'd also want to change the autosave options to store the files in an autosave directory. If I recall correctly, Matlab reads the colors and fonts from previous installations, so I don't have to do that.
I want to give credit to all open source libraries we use in our (commercial) application. I thought of showing a HTML page in our about dialog. Our build process uses ant and the third party libs are committed in svn.
What do you think is the best way of generating the HTML-Page?
Hard code the HTML-Page?
Switch dependency-management to apache-ivy and write some ant task to generate the html
Use maven-ant-tasks and write some ant task to generate the HTML
Use maven only to handle the dependencies and the HTML once, download them and commit them. The rest is done by the unchanged ant-scripts
Switch to maven2 (Hey boss, I want to switch to maven, in 1 month the build maybe work again...)
...
What elements should the about-dialog show?
Library name
Version
License
Author
Homepage
Changes made with link to source archive
...
Is there some best-practise-advice? Some good examples (applications having a nice about-dialog showing the dependencies)?
There are two different things you need to consider.
First, you may need to identify the licenses of the third-party code. This is often down with a THIRDPARTYLICENSE file. Sun Microsystems does this a lot. Look in the install directory for OpenOffice.org, for example. There are examples of .txt and .html versions of such files around.
Secondly, you may want to identify your dependencies in the About box in a brief way (and also refer to the file of license information). I would make sure the versions appear in the About box. One thing people want to quickly check for is an indication of whether the copy of your code they have needs to be replaced or updated because one of your library dependencies has a recently-disclosed bug or security vulnerability.
So I guess the other thing you want to include in the about box is a way for people to find your support site and any notices of importance to users of the particular version (whether or not you have a provision in your app for checking on-line for updates).
Ant task seems to be the best way. We do a similar thing in one of our projects. All the open source libraries are present in a specified folder. An Ant task reads the manifest of these libraries, versions and so on and generates an HTML, copies into another specified folder from where it is picked up by the web container.
Generating the page with each build would be wasteful if the libraries are not going to change often. Library versions may change, but the actual libraries don't. Easier to just create a HTML page would be the easiest way out, but that's one more maintenance head ache. Generate it once and include it with the package. The script can always be run again in case some changes are being made to the libraries (updating versions, adding new libraries).
Everyone managing open-source-software runs into the problem, that with the time the process of releasing a new version gets more and more work. You have to tag the release in your version-control, create the distributions (that should be easy with automated builds), upload them to your website and/or open-source-hoster. You have to announce the new release with nearly the same message on chosen web-forums, the news-system on sourceforge, mailinglists and your blog or website. And you have to update the entry of your software on freshmeat. Possible more tasks have to be done for the release.
Do you developed techniques to automate some of these tasks? Does software exist that supports you with this?
Pragmatic Project Automation shows how to do all of that. They use Ant for practically everything in the book, so if you know Ant you can make different targets to do any step in the build-release cycle.
For my Perl stuff, I wrote Module::Release. In the top-level directory I type a single command:
% release
If checks several things and dies if anything is wrong. If everything checks out, it uploads the distribution.
It automates my entire process:
Test against multiple versions of Perl
Test distribution files
Check the status of source control
Check for code and distribution quality metrics
Update changes file
Determine new version number
Release code to multiple places
Tag source control with new version number
Everyone seems to write their own release automator though. Most people like their process how they like their process, so general solutions don't work out that well socially.
Brad Fitzpatrick has ShipIt which is a Perl program to automate releases. There's slightly more info in his original announcement.