Software Management & Distribution: Creating Updates & Patches
Preface to the software updating problem...
Onrush of the modern software development, and also wide Internet
availability, have made usual the frequent release of new versions of
software programs. Prompt bugs / mistakes correction and feature adding are
those major factors which compel manufacturers to modify their software
products on a frequent basis. And if the overall size of the distribution
package of a software product is quite sizeable, then the necessity to
download the full new version distribution package can become an expensive
and tiresome procedure for end-users.
Most often, the size of the changes from one version to another is
significantly less than the size of the full distribution package, so many
developers could thought that it would be a good idea to have an opportunity
to implement software updating by delivering only those small changes by
size which distinguish the new version from the version already installed on
the end-user's machine. Well, an attempt to reduce the update data size as
much as possible is praiseworthy. However, how to make it really effective?
In case of the text data, everything is clear. There are a lot of excellent
algorithms for text files comparing and the text data can be compressed
effectively at that. But if you need to build an update package for
executable PE-files (exe, dll) then you will find out that these algorithms
are completely useless to make something worthwhile. Effective comparison of
executable files or any other binary files requires absolutely other
approaches.
Aspects of the software updating problem...
A problem of effective binary files comparing is not the only one in the
view of the software update task. The most important aspects which are
really worthy of notice are automation of patch building and delivery of the
update module to end-users.
Let's assume, that one day the number of your program versions has reached
21. It is obvious that the process of patch building for all these versions
and the following publishing of patches on the Internet will be quite
complicated even if you have some files/catalogues comparing tool.
Let's have a look what an end-user should perform to update a software
product:
- define the installed version number;
- go to your web-site to make sure that a newer version exists;
- probably he would like to read the changes history for the newer version comparing to the version he already has;
- find the required version update in the list;
- download and install the update package.
And moreover, active users will definitely like to receive new versions as
soon as possible, having applied minimum efforts to the update process. And
this wish is reasonable!
So, the main developer's task is to find the most effective, reliable and
reasonably-priced solution - and check if it is suitable for his particular
application.
Why use a Patching System and who needs it?
Patching simplifies your product management and makes it easy to manage your
software releases. There is no easier way to make professional quality,
full-history patches for your software and other electronic content.
Possible audience is software developers, network administrators and IT
managers, among others. Regardless of the type of data being distributed -
executables, documents, databases, videos, etc. - the patching system can
figure out what files have been changed, the exact changes within each file
and how to update any previous version to the current one.
Difference between incremental and binary patching...
Incremental update contains all the files which have been changed between
two versions. So the result patch can be rather large.
Update modules made with the help of the byte-level patching engine consist
only of the changes from within each individual file with the help of the
byte-level differencing technology used by patching engine, resulting in a
significantly smaller update size.
Let's have a look what a patch maker can offer...
Patch building (the main feature) can offer the efficiency and consequently
the small size of the result patch module. Other usefull features are
cumulative patching to bring all in-field versions up to date using a single
self-extracting executable; selection of the patch-building algorithm
efficiency and compression ratio, and also the maximum allowed size of the
files to be compared.
Patch installation - the main idea is to create fully customizable modules
with a wizard-style runtime interface; use of checksums to ensure accuracy;
provide the international language support for patches to be useful for
interanational audience of your software product; silent install and silent
uninstall with no user interaction required, which can be useful for system
administrators and other programs calling the Update Installation program;
smart automatic version check to determine the installed version; automatic
Rollback at patch applying to guarantee that the end-user's system is
successfully updated.
The main players in the market of patch building (which provides possibly
the most efficient patching engines) are RTPatch (
www.pocketsoft.com), and
PatchFactory (
www.agensoft.com), which are designed to automate all stages
of the update cycle for a software product or any other binary data.
Of course these product are different. This difference concerns flexibility
of licensing options, the total cost and consequently the variety of
solutions and environment functionality provided in the view of software
update creation.
You can observe the efficiency of these products' patching engines and the
range of offered services on those vendors' websites. Or just download the
evaluation version and start patching your software product!
