is an integrated package of classes and tools for development of service
applications and use of NT Security framework. Currently SvCom components
work with all Delphi versions under all
flavors of Windows. Features of SvCom are as follows:
SvCom includes on-line tutorial
that grows all the time. You can request
a new example.
The SvCom is a Try-Before-You-Buy software. Try it for free! SvCom sources
are available but for registered users only.
Debugging of SvCom-based services is far easier than debugging
services created without SvCom.
The standard advice for service debugging using the Delphi VCL
is to start your service from the Delphi IDE and then quickly
start the service using Control Panel. This is a nice trick but it is not convenient
and somtetimes it does not work (A service with DCOM server inside is a good example).
SvCom includes a powerful built-in service debugging tool. The idea of this tool
is simple: if an SvCom-based application is started with the "/debug"
switch it starts as an ordinary executable. Now the service will run in the debug
mode exactly as it would as a service but this time you can trace it as an ordinary
[Service recovery operations ]
Windows 2000 introduced a couple of new features for
services: it is a service description and service recovery on failure.
SvCom includes built-in support for all these features.
You can specify any of allowed recovery operations: service restart, command execution
or even computer reboot. Several recovery operations are allowed, Windows will
execute the next one in the list after service failure will occur. The counter
of failures can be reset to zero if the service works without failures for a given
time interval. Use this properties to make your service more reliable - with SvCom
it is easy now!
[DCOM Server in NT Service ]
The SvCom includes it`s own ActiveX framework.
It is partially based on native Delphi ActiveX framework but has some
serious differences. All SvCom class factories know about SvCom
services, this makes it possible to implement a DCOM server that will
live in a service. SvCom takes care of all necessary registry keys and
COM initialization. SvCom-based DCOM servers automatically support pausing
and stopping, it is even possible to have several services in one application
with several DCOM servers in each service. What's more SvCom
wizards make DCOM server in service creation as easy as possible.
Starting from SvCom 5.0 the DCOM support is essentially
enhanced: now you can easy create DCOM servers that support events,
allow creation of objects in apartment threads or use advances of singleton
MIDAS support is improved too. Now RemoteDataModules created
to work in service correctly register themselves in registry which greatly
simplifies the MIDAS-server-in-service creation.
[Interactive NT Services ]
The Delphi VCL was not designed to create interactive
services. The reason being that it uses some system information that
changes when interactive user logs off and logs on again. This will
cause any forms that are created after a logoff/logon appear damaged.
SvCom includes component that protects service forms
from being damaged even if logoff/logon occurs several times.
NT Services ]
SvCom's internal design allows several instances of
one service module to be created and then used as independent services.
Of course the names and some other attributes of each instance should
be changed to avoid problems with operating system.
Note, that with Delphi's service implementation it
is not possible to use several instances of one TService descendant.
[NT Service and windows messages ]
Standard services have no window handles at all, so
the only way to send a message to this kind of service is to send it
to the service thread. SvCom-base services do not have this limitation
and are able to receive and process windows messages. Therefore it is
possible to write a message handler for a service which will be called
when the service receives the corresponding message.
[Timer for NT Service ]
SvCom includes specialized timer component that
will work in a service. This automatically detects a service being started
or stopped causing an OnTimer event to occur in the service thread.
Just drop it onto an SvCom service module and it is ready for
use. If this component is dropped onto the form or an other module then
it functions exactly the same as Delphi's timer.
[SID, ACL, Security Descriptor... ]
The Windows NT security model includes a lot of objects
and rules concerning the use of these objects. Most of these objects
are variable-length records and their manipulation is additionally complicated
by memory allocations and deallocation.
This means that even simple tasks can require quite complicated
code to accommodate the NT security model. Most of these objects are
variable-length records and their manipulation is additionally complicated
by memory allocations and deallocation. SvCom includes a set of components
to deal with NT security objects such as SID, ACL, SECURITY_DESCRIPTOR
and so on. In addition components are provided to control user privileges
and access NT secret data storage. These components take care of the
correct memory allocation for security objects and conversion of their
representation. This greatly simplifies the manipulation of NT security
[Visual NT Security Controls]
SvCom's non-visual security components provide an easy
way to deal with NT security objects. Visual security-related SvCom
components provide all levels of functionality that are necessary
to design a user`s interface.
For example, SvCom includes the security descriptor editor
dialog. This is a configurable component that can be used to adjust
security of any NT securable object. It's security-editing capabilities
are much powerful then NT 4.0 and comparable with NT 2000.
[Is there an interactive user? ]
SvCom includes non-visual component that detects when
the interactive user logs on or off. There are no standard API
to solve this task. Microsoft recommendation is to analyze the list
of running processes to answer this question. This is the method is
employed by SvCom.
[List of processes ]
simple function that works both in WinNT and Win9x and returns the list
of processes in the string list.
and tools ]
SvCom includes several applications that are useful for
service development. They include
- Service Indicator - application that sits in tray and shows the
state of one selected service and allows control of it;
- Service Controller - command line service control tool