Home > Articles > Programming

This chapter is from the book

Custom Activities

This section first describes the reason for custom activities and then describes their technical characteristics.

Reason for Custom Activities

You are not limited to the OOB activities in WF. You can create your own. Creating custom activities is as core to WF as any other capability.

This section discusses three reasons to create custom activities: to improve on an OOB activity for usability reasons, to create domain specific activities, and to create custom control flow patterns.

Improve on OOB Activities

In Hour 17, "Learning Advanced Hosting," a third-party created synchronous InvokeWorkflow activity is explored. It is looked at because the OOB InvokeWorkflow activity only calls workflows asynchronously. Many scenarios call for calling workflows and waiting for the called workflow to return a response. Some may even choose to create an entirely new set of OOB activities. Improving the OOB activities is a viable scenario for custom activity development, but is not anticipated to be the primary motivation behind creating custom activities.

Create Domain-Specific Activities

The OOB activities provide general functionality. They are host agnostic and know nothing about any vertical domains or any individual enterprise. Many who use WF will find that its value grows proportionally to the amount of domain activities added. If, for example, you want to use WF to model the credit process, you could use the OOB activities for control flow and then augment them with standard code to perform the actual credit process. Alternatively, you could create Customer, CheckCredit, SendNotification, and other custom activities that augment the credit process. Figure 1.18 shows custom activities on a toolbox, and Figure 1.19 shows the custom Customer activity on a workflow and its properties.

Figure 1.18

Figure 1.18 CustomActivities toolbox.

Figure 1.19

Figure 1.19 Customer custom activity on workflow and its properties.

Create Custom Control Flow Patterns

A large portion of WF's utensil and ability to attract a wide range of authors is predicated on there being control flow activities that simplify modeling the respective process. The CAG activity, for instance, makes it possible to model data-driven workflows. The StateMachineWorkflow (workflows are themselves activities) allows for an event-driven style of workflows to be modeled. When nondevelopers are included as authors, there needs to be control flow activities appropriate for them.

Types of Custom Activities

Five types of custom activities exist in WF: basic, long-running, event-driven, control flow, and compound.

Basic activities are similar to standard components. They are called, and then execute, complete their work, and return in a finished state. A sample basic activity is a Customer activity that retrieves customer data. When creating a basic custom activity, you will override its execute method to tell it what to do. You may optionally also customize the activity's appearance, add it to the toolbox, and validate it. The next code snippet shows the code from the custom Customer activity discussed in the last section (variable declarations are omitted for brevity). You will create custom basic activities in Hour 20.

     [Designer(typeof(CustomerDesigner), typeof(IDesigner))]
     [ToolboxBitmap(typeof(Customer), "Resources.Customer.jpg")]
     public partial class Customer : System.Workflow.ComponentModel.Activity
         protected override ActivityExecutionStatus
 Execute(ActivityExecutionContext executionContext)
            // Perform preprocessing.
            base.RaiseEvent(Customer.InvokingEvent, this, EventArgs.Empty);

            SqlConnection dbConn = new SqlConnection(ConnectionString);
            SqlCommand getCustomer = new SqlCommand("GetCustomer", dbConn);

            getCustomer.CommandType = System.Data.CommandType.StoredProcedure;

            using (SqlDataReader custReader =
                if (custReader.Read())
                    CustomerName = custReader["CustomerName"].ToString().Trim();
                    CustomerCreditLimit =
                    CustomerType = custReader["CustomerType"].ToString().Trim();
                    CustomerYtdSales =
                    CustomerHoldRules =
                ("The customer number is: " + CustomerNumber);
                 ("The customer name is: " + CustomerName);
                ("The customer credit limit is: " + CustomerCreditLimit);
                ("The customer type is: " + CustomerType);
                ("The customer YTD sales is: " + CustomerYtdSales);
                ("The customer hold rules is: " + CustomerHoldRules);
            return ActivityExecutionStatus.Closed;

Following is a summary of the additional custom activity types in WF. These activities build on the steps necessary to create a basic activity.

Long-running activities do not complete on initial call. They continue processing on another thread. They return control to the workflow while the processing occurs. When the processing completes on the other thread, the long-running activity notifies the workflow that it is complete (via WF's internal queuing system). The same Customer activity can also be coded as a long-running activity. The reason is that if the database call to retrieve the customer information was to a local database and was fast, it would make sense to do all work in the execute method. If the call was across the firewall and not so fast, it might be better to return control before the customer data is retuned. Hour 21, "Creating Queued Activities," demonstrates modifying the Customer activity, shown in the previous code listing, that currently executes in one part to execute in two distinct parts.

Event-driven custom activities can wait for external events inside of a Listen or other activity. Custom event-driven activities are described in Hour 22, "Creating Typed Queued and EventDriven-Enabled Activities."

Composite or control flow activities, as previously mentioned, allow you to create your own control flow patterns. These activities are responsible for determining which child activities should execute and then scheduling them for execution. Creating custom composite activities is discussed in Hour 23, "Creating Control Flow Activities Session 1," and Hour 24, "Creating Control Flow Activities Session 2."

A compound activity is prepopulated with other activities. It is useful when a pattern of activities is commonly used. Figure 1.20 demonstrates a CreditCheck compound activity that uses the custom Customer activity to retrieve customer data; then it uses the CheckCredit activity to determine if the customer is on credit hold. Finally, it evaluates the return results in an IfElse activity. The left branch processes the order, and the right branch rejects it. You will create this compound activity in Hour 20.

Figure 1.20

Figure 1.20 Compound credit check activity.

All noncomposite activities derive (directly or indirectly) from System.Workflow.ComponentModel.Activity. Composite activities all derive from System.Workflow.ComponentModel.CompositeActivity. These are the same classes the BAL activities derive from.

Custom activities are covered in Hours 20 to 24.

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.


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.


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.


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.


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


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


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.


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.


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