Home > Articles > Software Development & Management

Framework Design Guidelines: Domain Logic Patterns

Martin Fowler discusses Transcription Script, Domain Model, Table Module and Service Layer.
This chapter is from the book

Transaction Script

Organizes business logic by procedures where each procedure handles a single request from the presentation.

Most business applications can be thought of as a series of transactions. A transaction may view some information as organized in a particular way, another will make changes to it. Each interaction between a client system and a server system contains a certain amount of logic. In some cases this can be as simple as displaying information in the database. In others it may involve many steps of validations and calculations.

A Transaction Script organizes all this logic primarily as a single procedure, making calls directly to the database or through a thin database wrapper. Each transaction will have its own Transaction Script, although common subtasks can be broken into subprocedures.

How It Works

With Transaction Script the domain logic is primarily organized by the transactions that you carry out with the system. If your need is to book a hotel room, the logic to check room availability, calculate rates, and update the database is found inside the Book Hotel Room procedure.

For simple cases there isn't much to say about how you organize this. Of course, as with any other program you should structure the code into modules in a way that makes sense. Unless the transaction is particularly complicated, that won't be much of a challenge. One of the benefits of this approach is that you don't need to worry about what other transactions are doing. Your task is to get the input, interrogate the database, munge, and save your results to the database.

Where you put the Transaction Script will depend on how you organize your layers. It may be in a server page, a CGI script, or a distributed session object. My preference is to separate Transaction Scripts as much as you can. At the very least put them in distinct subroutines; better still, put them in classes separate from those that handle presentation and data source. In addition, don't have any calls from the Transaction Scripts to any presentation logic; that will make it easier to modify the code and test the Transaction Scripts.

You can organize your Transaction Scripts into classes in two ways. The most common is to have several Transaction Scripts in a single class, where each class defines a subject area of related Transaction Scripts. This is straightforward and the best bet for most cases. The other way is to have each Transaction Script in its own class (Figure 9.1), using the Command pattern [Gang of Four]. In this case you define a supertype for your commands that specifies some execute method in which Transaction Script logic fits. The advantage of this is that it allows you to manipulate instances of scripts as objects at runtime, although I've rarely seen a need to do this with the kinds of systems that use Transaction Scripts to organize domain logic. Of course, you can ignore classes completely in many languages and just use global functions. However, you'll often find that instantiating a new object helps with threading issues as it makes it easier to isolate data.

I use the term Transaction Script because most of the time you'll have one Transaction Script for each database transaction. This isn't a 100 percent rule, but it's true to the first approximation.

When to Use It

The glory of Transaction Script is its simplicity. Organizing logic this way is natural for applications with only a small amount of logic, and it involves very little overhead either in performance or in understanding.

As the business logic gets more complicated, however, it gets progressively harder to keep it in a well-designed state. One particular problem to watch for is its duplication between transactions. Since the whole point is to handle one transaction, any common code tends to be duplicated.

Careful factoring can alleviate many of these problems, but more complex business domains need to build a Domain Model (116). A Domain Model (116) will give you many more options in structuring the code, increasing readability and decreasing duplication.

It's hard to quantify the cutover level, especially when you're more familiar with one pattern than the other. You can refactor a Transaction Script design to a Domain Model (116) design, but it's a harder change than it otherwise needs to be. Therefore, an early shot is often the best way to move forward.

However much of an object bigot you become, don't rule out Transaction Script. There are a lot of simple problems out there, and a simple solution will get you up and running much faster.

The Revenue Recognition Problem

For this pattern, and others that talk about domain logic, I'm going to use the same problem as an illustration. To avoid typing the problem statement several times, I'm just putting it in here.

Revenue recognition is a common problem in business systems. It's all about when you can actually count the money you receive on your books. If I sell you a cup of coffee, it's a simple matter: I give you the coffee, I take your money, and I count the money to the books that nanosecond. For many things it gets complicated, however. Say you pay me a retainer to be available that year. Even if you pay me some ridiculous fee today, I may not be able to put it on my books right away because the service is to be performed over the course of a year. One approach might be to count only one-twelfth of that fee for each month in the year, since you might pull out of the contract after a month when you realize that writing has atrophied my programming skills.

The rules for revenue recognition are many, various, and volatile. Some are set by regulation, some by professional standards, and some by company policy. Revenue tracking ends up being quite a complex problem.

I don't fancy delving into the complexity right now, so instead we'll imagine a company that sells three kinds of products: word processors, databases, and spreadsheets. According to the rules, when you sign a contract for a word processor you can book all the revenue right away. If it's a spreadsheet, you can book one-third today, one-third in sixty days, and one-third in ninety days. If it's a database, you can book one-third today, one-third in thirty days, and one-third in sixty days. There's no basis for these rules other than my own fevered imagination. I'm told that the real rules are equally rational.

Example: Revenue Recognition (Java)

This example uses two transaction scripts: one to calculate the revenue recognitions for a contract and one to tell how much revenue on a contract has been recognized by a certain date. The database structure has three tables: one for the products, one for the contracts, and one for the revenue recognitions.

CREATE TABLE products (ID int primary key, name varchar, type varchar) 
CREATE TABLE contracts (ID int primary key, product int, revenue decimal, dateSigned date)
CREATE TABLE revenueRecognitions (contract int, amount decimal, recognizedOn date,
                                  PRIMARY KEY (contract, recognizedOn))

The first script calculates the amount of recognition due by a particular day. I can do this in two stages: In the first I select the appropriate rows in the revenue recognitions table; in the second I sum up the amounts.

Many Transaction Script designs have scripts that operate directly on the database, putting SQL code in the procedure. Here I'm using a simple Table Data Gateway (144) to wrap the SQL queries. Since this example is so simple, I'm using a single gateway rather than one for each table. I can define an appropriate find method on the gateway.

class Gateway... 

   public ResultSet findRecognitionsFor(long contractID, MfDate asof) throws SQLException{
      PreparedStatement stmt = db.prepareStatement(findRecognitionsStatement);
      stmt = db.prepareStatement(findRecognitionsStatement);
      stmt.setLong(1, contractID);
      stmt.setDate(2, asof.toSqlDate());
      ResultSet result = stmt.executeQuery();
      return result;
   private static final String findRecognitionsStatement =
      "SELECT amount " +
      "FROM revenueRecognitions " +
      "WHERE contract = ? AND recognizedOn <= ?";
   private Connection db;

I then use the script to sum up based on the result set passed back from the gateway.

class RecognitionService... 

   public Money recognizedRevenue(long contractNumber, MfDate asOf) {
      Money result = Money.dollars(0);
      try {
         ResultSet rs = db.findRecognitionsFor(contractNumber, asOf);
         while (rs.next()) {
            result = result.add(Money.dollars(rs.getBigDecimal("amount")));
         return result;
      }catch (SQLException e) {throw new ApplicationException (e);

When the calculation is as simple as this, you can replace the in-memory script with a call to a SQL statement that uses an aggregate function to sum the amounts.

For calculating the revenue recognitions on an existing contract, I use a similar split. The script on the service carries out the business logic.

class RecognitionService... 

   public void calculateRevenueRecognitions(long contractNumber) {
      try {
         ResultSet contracts = db.findContract(contractNumber);
         Money totalRevenue = Money.dollars(contracts.getBigDecimal("revenue"));
         MfDate recognitionDate = new MfDate(contracts.getDate("dateSigned"));
         String type = contracts.getString("type");
         if (type.equals("S")){
            Money[] allocation = totalRevenue.allocate(3);
               (contractNumber, allocation[0], recognitionDate);
               (contractNumber, allocation[1], recognitionDate.addDays(60));
          (contractNumber, allocation[2], recognitionDate.addDays(90));
         }else if (type.equals("W")){
            db.insertRecognition(contractNumber, totalRevenue, recognitionDate);
         }else if (type.equals("D")) {
            Money[] allocation = totalRevenue.allocate(3);
                (contractNumber, allocation[0], recognitionDate);
               (contractNumber, allocation[1], recognitionDate.addDays(30));
               (contractNumber, allocation[2], recognitionDate.addDays(60));
      }catch (SQLException e) {throw new ApplicationException (e);

Notice that I'm using Money (488) to carry out the allocation. When splitting an amount three ways it's very easy to lose a penny.

The Table Data Gateway (144) provides support on the SQL. First there's a finder for a contract.

class Gateway... 

   public ResultSet findContract (long contractID) throws SQLException{
      PreparedStatement stmt = db.prepareStatement(findContractStatement);
      stmt.setLong(1, contractID);
      ResultSet result = stmt.executeQuery();
      return result;
   private static final String findContractStatement =
      "SELECT * " +
      "FROM contracts c, products p " +
      "WHERE ID = ? AND c.product = p.ID";

And secondly there's a wrapper for the insert.

class Gateway... 

   public void insertRecognition (long contractID, Money amount, MfDate asof) throws SQLException {
      PreparedStatement stmt = db.prepareStatement(insertRecognitionStatement);
      stmt.setLong(1, contractID);
      stmt.setBigDecimal(2, amount.amount());
      stmt.setDate(3, asof.toSqlDate());
   private static final String insertRecognitionStatement =
      "INSERT INTO revenueRecognitions VALUES (?, ?, ?)";

In a Java system the recognition service might be a regular class or a session bean.

As you compare this to the example in Domain Model (116), unless your mind is as twisted as mine, you'll probably be thinking that this is much simpler. The harder thing to imagine is what happens as the rules get more complicated. Typical revenue recognition rules get very involved, varying not just by product but also by date (if the contract was signed before April 15 this rule applies …). It's difficult to keep a coherent design with Transaction Script once things get that complicated, which is why object bigots like me prefer using a Domain Model (116) in these circumstances.

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