Many WEB developers are asking "What is the difference", "Does ALP
replace PWS" or "Does ALP use PWS components". I'll try to answer in this article.
While Microsoft's Personal Web Server (PWS) is a WEB server ALP is not. PWS is a fully
functional Internet Information Server (with some limitations) thus it is a server side
software. Contrary ALP is a client side software that implements features usually found on
the WEB servers, but it implements them in a set of in-process components and it is
implemented as an asynchronous pluggable protocol.
ALP is easy to install - it requires just a seconds and does not depend on additional
server side software like the PWS. There is no limitations for the number of ALP
sites and no network configuration is needed. Even it can work quite well without TCP/IP
network installed on the machine!
You can think about ALP in the same manner as you think for the VB runtime DLLs -
engine used by certain applications. Difference is the orientation - VB "thinks"
for the forms and VB modules - ALP powers WEB pages/forms, executable scripts/programs and
native ALP extensions. Thus some well known technologies used before only for WEB
programming are available for desktops and become applicable in new areas.
Thus ALP implements Internet technologies in the desktop environment. Probably the
first question will be about the benefits of such solution:
- Installation does not disturb the user - he/she just starts the ALPInstall then the
application(s) working with ALP can be used as any other desktop application.
- Core components are small - less than 500Kb
- ALP applications doesn't need configuration settings, creation of virtual directories or
sites. Configuration files placed with them will be enough in any location (if the
programmer takes care to not hardcode local paths- it is easy to do but often forgotten).
- WEB programmers using ALP are able to build desktop software with the familiar
techniques. This software will be able to run on a WEB server too - thus there is no need
to spend time for building two versions.
- There are many companies using intranet software written in ASP and CGI scripts. Without
ALP they need to install PWS or some other WEB server on the local machines in the small
offices. This costs too much work for the administrators. Using ALP compatible software
packages can be prepared and installed easily. Administrators are able to prepare
configurations and installation packages once and distribute them without need to go to
the every office every time when new application must be installed.
- And ALP can run without installation - for example directly from CD-ROM. More details
will be published with the ALPFrame utility until the end of June 2001.
Of course most people will ask "What are the weak sides?". Yes ALP is not a
general solution for everything but it solves some problems caused by mixing the Internet
technologies with desktop programs. Now and in the future the target of the ALP will
be supplying one common environment for desktop and WEB programming. We
will extend it to reach areas not covered in the first version.
I can sort the weak sides in two parts - first features that will be added soon and
other features that will not be implemented in order to keep it portable and compatible
with the most Windows OS-es. In the first part are such features like global.asa support
and cookies in the second are hard integration with the Microsoft Transaction Server (on
the systems prior to Win2k) and features not applicable outside the IIS environment.
Documentation describes all the features without hiding anything.
I'll be glad to answer your questions.