Home > Articles > Programming > Windows Programming

Configuration Data

  • Print
  • + Share This
This chapter is from the book

Persistent Storage

There are many techniques from which to choose. The following is a list of a number of them, although the list is not exhaustive:

  • Using the usual database
  • Using the Registry
  • Using Active Directory
  • Using Object Construction (OC)
  • Using a .config file

Let's discuss each of these techniques a little further. When you read this discussion, please keep in mind that it's not my intention that the persistent storage should be hit each time the configuration data is needed; rather, it should be only hit once or at least infrequently. (The second part of the solution, how to access the configuration data in transient storage, will further explain this.)

Using the Usual Database

The first technique, using the usual database for holding configuration data, might seem a bit strange, but this is often a really good idea. The good thing about it is that you have one centralized place for the stored configuration data, even if you have a cluster of application servers. You also have the protection of transactions if that is a requirement for you in this case. One drawback could be that you waste some scarce resources when you have to hit the database for fetching configuration data, too. This is not usually a problem because you will rarely hit persistent storage for configuration data, but it's still something to think about.

I know, I know. Storing connection strings in the database is not a good solution, at least not if the connection strings describe how to reach the database.

Using the Registry

I have to confess that I used .ini files long after the Registry was introduced, but after a while I started to like the solution that the Registry represents. (Sure, I see the problems with it, too, but I still like it.) As you know, Microsoft has now more or less put the Registry on the legacy list, and you're not supposed to use it anymore, mainly because it creates a more difficult deployment situation compared to using .config files instead, for example.

You will normally use the Registry class in the Microsoft.Win32 namespace as the entry point when working with the Registry in .NET.

Using Active Directory

You can think of Active Directory as the "Registry," but it spans all the machines in your network and all the information found on all machines. For many developers, it has become a popular place for storing connection strings and similar items.

It was hard to work with Active Directory (or, rather, ADSI) from VB6, but it's now much easier in .NET. You start by using the DirectoryEntry class of the System.DirectoryServices namespace for finding information in the Active Directory.

Using Object Construction (OC)

COM+ 1.0 made it possible to store a string in the COM+ catalog for a specific component and then retrieve that value when an object of the component was activated. This is still a useful and viable solution for serviced components. As you will see in the next section, I see OC both as a solution for the persistent storage and also as an access mechanism. However, you can also use it just as a persistent storage mechanism so that when you find that you need to read the value from persistent storage, you instantiate an object of the component that is using OC, grab the value, and store it in transient storage.

Listing 1 shows code that illustrates how OC can be used for serviced components. As you can see there, I override the Construct() method, and the parameter called constructString is the string that can be changed in the Component Services Explorer.

Listing 1: Example Showing How to Use OC in a Serviced Component

Imports System.EnterpriseServices
<ConstructionEnabled
(Default:="Hello world")> _
Public Class OcTest
  Inherits ServicedComponent
  Private m_Data As String

  Protected Overrides Sub Construct _
  (ByVal constructString As String)
    m_Data = constructString
  End Sub

  'And some more methods...

End Class

Using a .config File

.config files are files in XML format for holding configuration data. They were introduced in .NET as a solution for helping with XCOPY deployment. (With XCOPY deployment, a single XCOPY command deploys an application at another server. There are no Registry settings that have to be written, no registrations of DLLs, and so on.)

.config files can be used for configuring the built-in tracing solution in .NET, as well as your own tracing solution.

Unfortunately, .config files don't work so well with serviced components. .config files are for EXEs rather than DLLs, and that is pretty natural. Consider a DLL that is shared by several EXEs. It should probably be possible to use different settings for each EXE. So far, so good.

The problem is that COM+ server applications are executed by the surrogate EXE called Dllhost, and there is only one EXE for all COM+ applications, so it's problematic to use the settings for, say, built-in tracing in the .config file. It's also the case that Dllhost isn't written in managed code, and it doesn't know that it should load a .config at all. This is why it's also problematic to use the System.Configuration namespace. Finally, you will have to keep the .config file in the same directory as the Dllhost EXE, and it's located in your system32 directory. So much for XCOPY deployment.

NOTE

Yet another problem with using .config files is that the built-in tracing solution won't refresh the values found in the .config file. Instead, the .config file is read only once for the process. This is not a big problem for a Windows Forms application, but it might be a huge problem for a COM+ application.

Instead, I have decided to use a custom approach for reading .config files from COM+ applications. I use the format of .config files, but I give them the name of the DLL to which they belong (same value as for AssemblyGlobal.exeOrDllName constant). First I thought about having the .config files together with the DLLs, but the GAC creates a problem for this. Therefore, I decided that the .config files will be stored in one specific directory. I have decided to use c:\complusapps. Then I use custom code for parsing the .config files, so this approach is quite easy after all.

NOTE

An interesting white paper that is not only related to adding support for debugging but also about configuration data is Amitabh Srivastava and Edward Jezierski's "Monitoring in .NET Distributed Application Design." The paper discusses Windows Management Instrumentation (WMI) and how it can be used for updating .config files, which is just another advantage of the technique of .config files.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020