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Overview of the Online Bookstore Sample

Visual Studio 6.0
 

Rob Caron
Microsoft Corporation

July 1999

Summary: Looks at Online Bookstore, a Web-based bookseller. Discusses the strategies and considerations involved in the development of this interoperability sample application. Concludes with a walk-through of the application. (21 printed pages)

Note   The Online Bookstore sample files can be downloaded from "Setting Up the Online Bookstore Sample."

Introduction

A fictitious mail-order bookseller specializing in titles from Microsoft® Press has decided to expand its business reach by launching a Web site, Online Bookstore. Because the company has an established order-processing system with large investments in mid-range and mainframe systems, it has decided to create a Web-commerce solution that will leverage these existing systems.

The key motivation for the project is to get a presence on the Web as soon as possible, because sales have declined following the advent of other online booksellers. This is the first endeavor of its kind for this company; therefore, project goals include keeping overall lifetime project costs low by utilizing existing infrastructure when possible and providing a low-cost-to-support solution. Performance is important but secondary to supportability costs and a short-term rollout schedule. If successful, the company will revisit the design to identify areas for improvement.

As a result of mergers and acquisitions, the company’s enterprise data resides in a variety of data stores. For instance, customer information is kept in an Oracle 8 database running on a Sun SPARC/Solaris system. Order and inventory data is stored in an IBM DB2 database running on an IBM MVS system inherited from a merger with another bookseller. CICS programs on this system are used to process credit card authorizations. The company’s shipping system is run from an IBM AS/400, with the shipping data stored in keyed, physical files.

Design

The Online Bookstore sample application is designed using the Microsoft® Windows® Distributed interNet Application (Windows DNA) architecture application development model. The application is implemented in three layers: a data layer, a business layer, and a presentation layer. The data layer represents the myriad of data sources distributed across the company’s enterprise system. The business layer consists of several components running in one Microsoft® Transaction Server (MTS) package. This layer uses technologies provided by Microsoft® SNA Server to access the mainframe and AS/400. The presentation layer is a Web site hosted on Microsoft® Internet Information Server (IIS), which provides a thin client to the customer using a Web browser.

Data Layer

The data layer of the Online Bookstore consists of four data sources disbursed across four individual machines in the company’s enterprise system. This data is accessed from the application’s business component using Microsoft® ActiveX® Data Objects (ADO) and the application’s data component, which provides connectivity to the data sources. ADO uses OLE DB to access each data source using OLE DB providers that provide the required functionality to interact with each data source.

Data sources

Data used by the Online Bookstore is kept in AS/400 keyed, physical files, an IBM DB2 database, an Oracle 8 database, and a Microsoft® SQL Server™ 7.0 database.

AS/400

The company’s shipping system is run on an IBM AS/400, with shipping data kept in keyed, physical files on the system. Each file represents one table of information. Metadata stored by the system is used to describe the data stored in each file, such as column descriptions. There are three files that are used by the Online Bookstore application: ShipCost, ShipMethod, and TrackNum.

Table Data
ShipCost Shipping costs associated with each available shipping method.
ShipMethod Available shipping methods.
TrackNum Next available shipment tracking number.

DB2

The company’s inventory and order data is kept in an IBM DB2 database that is running on an IBM MVS mainframe. Detailed information concerning each of the available titles sold by the company is stored here also for use in producing the mail-order catalog. This information is periodically replicated on the SQL Server database used by the Web site to minimize the amount of traffic on the DB2 caused by customers browsing the Web site. The Online Bookstore application uses four tables: Inventory, OrderDetails, OrderID, and Orders.

Table Data
Inventory Current stock level of each title sold by the company.
OrderDetails Information about each title in an order.
OrderID Next available order ID number.
Orders Information about each order.

Oracle

The company’s customer information is kept in an Oracle 8 database that is running on a Sun SPARC/Solaris midrange computer. Both the online ordering system and the traditional ordering systems use this database. The Online Bookstore application uses two tables: CustomerID and Customers.

Table Data
CustomerID Next available customer ID number.
Customers Detailed information about each customer.

SQL Server

Information about each title is kept in a SQL Server database that is running on a Windows NT® server. As mentioned earlier, this information is kept in an IBM DB2 database and periodically replicated to the SQL Server database. The Online Bookstore application uses three tables: Categories, TitlePrice, and Titles.

Table Data
Categories Categories by which titles are categorized.
TitlePrice Suggested retail and sale price of each title.
Titles Detailed information about each title.

Data access methods

To access all of the data sources listed earlier, the Online Bookstore application uses ADO and, subsequently, OLE DB. Much of the power and flexibility of ADO comes from its ability to connect to any of several different data providers and still expose the same programming model—regardless of the specific features of any given provider. However, because each data provider is unique, how the Online Bookstore application interacts with ADO will vary slightly between the different data providers. These differences are primarily related to the connection parameters, ADO Command object usage, and the behavior of the ADO Recordset object.

Microsoft OLE DB Provider for AS/400 and VSAM considerations

The Microsoft® OLE DB Provider for AS/400 and VSAM makes it possible for ADO to access and manipulate OS/400 and VSAM file system files at the record level. The provider uses the record-level input/output (RLIO) protocol of the IBM Distributed Data Management (DDM) architecture. The provider is implemented as a source-only DDM server, meaning it cannot act as a target DDM server capable of processing requests from a source DDM server. Because the target DDM servers are resident on host systems, no Microsoft software is required to be placed on the host systems.

AS/400 files can be classified as being either system-described or program-described. System-described files, such as logical files and keyed, physical files, are defined by metadata maintained by the operating system. An AS/400 logical file is similar to a view in a database, while an AS/400 keyed, physical file is similar to a table in a database. Metadata for program-described files are not kept by the operating system. Accessing these files requires a Host Column Description (HCD) file, which contains the required metadata. Program-described files on an AS/400 are usually referred to as flat files.

VSE (Virtual Storage Extended) and MVS (Multiple Virtual Storage) mainframe VSAM (Virtual Sequential Access Method) files are classified as being system-described and require an accompanying HCD file to make it possible for this provider to access them.

The provider permits connection to host files through an Advanced Peer-to-Peer Communication (APPC) LU6.2 connection using SNA Server. Alternatively, the provider can use a direct TCP/IP connection to the DDM TCP/IP port on the destination host computer. The chosen connection method will dictate the parameters required in the ADO Connection object’s ConnectionString property.

In ADO, the Command object is used to open a rowset (table) from a host file using DDM-specific commands or by executing Command Language (CL) commands on an AS/400 target DDM server. These commands are specified in the Command object’s CommandText property. The Command object’s CommandType property must be set to adCmdText. Because this provider implements only record-oriented access, access to data using SQL statements or host-based, stored procedures with this provider is not supported.

By default, the provider uses a server-based cursor. All indexed file access is based on a cursor located over the host file and not a local PC copy of the file. The provider can be configured to use a client-based cursor provided by the Microsoft® Data Access Components (MDAC) cursor services; however, using a client-based cursor limits access to the host files to read-only.

The provider does not currently support automatic enlistment in MTS transactions, nor does it support distributed transactions.

Microsoft® OLE DB Provider for DB2 considerations

The Microsoft OLE DB Provider for DB2 makes it possible for ADO to access and manipulate data in an IBM DB2 database. This provider is implemented as an IBM Distributed Relational Database Architecture (DRDA) application requester. As such, this provider can connect to most of the popular DRDA-compliant DB2 systems.

The provider permits connection to DB2 systems through an APPC LU6.2 connection using SNA Server or a direct TCP/IP connection. The chosen connection method will dictate the parameters required in the ADO Connection object’s ConnectionString property. Refer to the provider’s documentation to determine your connection choice, because not all DB2 systems are accessible from each type of connection.

The provider uses DB2 packages to issue dynamic and static SQL statements. There is a provider-specific property that the provider uses to identify a location in which to create and store DB2 packages. The provider will dynamically create packages in this specified location.

The provider supports remote database access from the Microsoft® Distributed Query Processor (DQP), which is demonstrated in the Online Bookstore application. To support this, the provider must be run in-process. When creating a DQP Linked Server, you must configure this provider to be loaded in-process. This procedure is discussed in the setup documentation that accompanies the Online Bookstore application.

By default, the provider uses a server-based cursor. All data access is based on a cursor located at the DB2 database. The provider can be configured to use a client-based cursor provided by the MDAC cursor services; however, using a client-based cursor limits access to the data to read-only.

To ensure data integrity, use the FOR UPDATE OF clause when creating a recordset that will be updated. This locks the data page when the data is fetched, ensuring no other process can modify the data before your program processes it. After the clause, specify only those columns that will be updated.

Code all read-only SELECT statements with the FOR READ ONLY cursor clause. This will ensure the cursor is unambiguous and can utilize a block fetch. When using a block fetch, the returned rows are grouped into a single block of data.

The provider does not currently support automatic enlistment in MTS transactions, nor does it support distributed transactions.

Microsoft® OLE DB Provider for Oracle considerations

The Microsoft OLE DB Provider for Oracle makes it possible for ADO to access and manipulate data in an Oracle database. The provider is a native provider that can only expose what Oracle can expose through the Oracle Call Interface API.

The provider permits connection to Oracle 7.3 or later databases. To use this provider, the Oracle networking components and client software must be installed on the same machine as the OLE DB provider. Because the provider uses the Oracle networking components to connect to the Oracle server, the ConnectionString property of the ADO Connection object only requires the name of an Oracle server available on the network and an Oracle username and password.

The Command object can be used to execute Oracle stored procedures using either the ODBC or the native Oracle PL/SQL syntax.

Currently, the provider only exposes forward-only, read-only rowsets. As a result, the only method to update information in Oracle using this provider is to issue a separate SQL UPDATE statement.

To obtain a scrollable cursor, specify the cursor location as adUseClient, the cursor type as adOpenStatic, and the lock type as adLockOptimistic. When working with large rowsets, you might want to specify that the rowset be obtained asynchronously using the adAsyncFetch option. This will return control to your application more quickly while the rowset is being constructed.

However, for optimal performance when a scrollable cursor is not required, it is best to set the cursor location to adUseServer, the cursor type to adOpenForwardOnly, and a lock type of adLockReadOnly.

The provider can participate in distributed or coordinated MTS transactions by using Microsoft® Distributed Transaction Coordinator (DTC).

Microsoft® OLE DB Provider for SQL Server considerations

The Microsoft® OLE DB Provider for SQL Server provides native access to SQL Server. The provider uses a set of system stored procedures called catalog stored procedures to obtain information from the SQL Server system catalog.

The provider permits connection to SQL Server 6.5 or later databases, communicating with network software through the SQL Server Net-Library interface.

SQL Server 7.0 fully supports OLE DB as a native programming interface, thus fully supporting applications that use ADO and OLE DB. SQL Server 7.0 uses OLE DB for communication between internal components and between SQL Server installations when using remote stored procedures. In addition, the provider supports rowsets from linked servers to support heterogeneous queries with other OLE DB data sources. Using this provider and Data Transformation Services (DTS), data can be moved and transformed between SQL Server 7.0 and any other OLE DB data provider.

The provider can participate in distributed or coordinated MTS transactions by using DTC.

Business Layer

The business layer of the Online Bookstore is contained in an MTS package that consists of the data, business, and COMTI components. The data and business components are implemented in Microsoft® Visual Basic® and provide the bulk of the functionality associated with the package. The COMTI component is an automation server that works with the COMTI run-time proxy to communicate with mainframe programs.

Data component

The data component, TierData, is an interface to the Online Bookstore data layer providing ADO Connection objects to the business component for a variety of data sources. The data component consists of one class module called cData.

cData.cls

Procedure Purpose
AS400Conn Provides an ADO Connection object that is connected to an IBM AS/400 using the OLE DB Provider for AS/400 and VSAM.
DB2Conn Provides an ADO Connection object that is connected to an IBM DB2 database using the OLE DB Provider for DB2.
OracleConn Provides an ADO Connection object that is connected to an Oracle database using the OLE DB Provider for Oracle.
SQLConn Provides an ADO Connection object that is connected to a SQL Server using the OLE DB Provider for SQL Server.

Business component

The business component, TierLogic, provides the essential business logic for the Online Bookstore. The business component consists of one code module, Globals, and seven class modules: cCartItems, cCategory, cCustomer, cInventory, cMarketing, cOrder, and cTitle.

Globals.bas

Globals.bas provides a central location in the business component for functionality used throughout the component.

Procedure Purpose
CreateOjbectInContext Creates the requested object in the context of the requesting object in MTS.

cCartItems.cls

This class represents the customer’s shopping cart. It is a collection class for creating an object composed of a collection of cTitle objects. Each cTitle object represents a selected title in the shopping cart.

Procedure Purpose
FillCart Fills the shopping cart with the items the customer has selected for purchase by building a collection of cTitle objects.
Add Creates a cTitle object and adds it to the cart.
Remove Removes a cTitle object from the cart.

cCategory.cls

This class provides functionality related to title categories. It is used to retrieve information regarding a particular category.

Procedure Purpose
LoadCategory Retrieves detailed category information.

cCustomer.cls

This class provides functionality related to a particular customer. It is used to both save and retrieve customer information.

Procedure Purpose
Login Authenticates customer credentials.
GetCustomerByEMail Retrieves customer information using the customer’s e-mail address.
Add Adds a new customer to the database.
Save Saves customer data to the database.
GetNextCustID Obtains the next available customer ID.

cInventory.cls

This class provides functionality related to the current inventory of titles. It is used to both check and debit inventory.

Procedure Purpose
GetWarnings Generates low stock warnings when requested.
OnHand Gets the current quantity of a title in stock.
RemoveFromInventory Debits the title inventory at purchase time.

cMarketing.cls

This class provides functionality related to how titles are marketed on the Web site. It is used to package title information in a manner to entice the customer to purchase selected titles.

Procedure Purpose
GetBestSellers Gets a listing of the current best sellers.
GetFeaturedTitles Gets a listing of the featured titles.
GetNewTitles Gets a listing of the newest titles.
GetCategoryList Gets a listing of all title categories.
GetTitlesForCategory Gets a listing of all titles in a category.
GetRemainingCategories Gets a listing of all but the current category.
GetFewSentences Parses out the first few sentences to create blurbs for the featured titles.

cOrder.cls

This class provides functionality related to the processing of a customer’s order. This class also handles request for information regarding previous orders.

Procedure Purpose
Process Processes a customer’s order.
CheckOrderStatus Checks the status of orders placed by a customer.
GetShipMethodByID Gets the name of a ship method using a ship method ID.
GetShipCostPerItem Gets the shipping cost per item for a particular shipping method.
GetNextOrderID Gets the next available order ID.
GetShipCostBaseRate Gets the base shipping cost for a particular shipping method.
GetShipMethods Gets a listing of the available shipping methods.

cTitle.cls

This class provides functionality related to title information. Each instance of an object created from this class represents a single title.

Procedure Purpose
LoadTitle Retrieves detailed information for a title.

COMTI Component

The COMTI component, CreditCard, works in conjunction with the COMTI run-time proxy to provide an interface to a mainframe program that authorizes credit cards.

Merchant

This class provides an interface to the mainframe program that is run on the mainframe. This class contains an interface only and no actual code, which exists on the mainframe.

Procedure Purpose
GetApproval Authorizes credit cards prior to processing order.

Presentation Layer

The presentation layer of the Online Bookstore consists of a Web site hosted from an IIS Web server, and a browser that serves as a thin client on the customer’s computer. The presentation layer is implemented using Microsoft® Active Server Pages (ASP) written primarily in Microsoft® Visual Basic® Scripting Edition (VBScript) to provide a dynamic interface to the customer. All images used on the Web site are stored on the Web server in an images directory. For educational purposes, Macromedia Shockwave files have been provided to demonstrate the operation of each of the primary pages on the site.

File Purpose
Images/*.gif Contains book cover art.
Shockwave/*.swf Contains Macromedia Shockwave files.
Styles/style.css Contains the cascading style sheet for this Web site.
AboutApp.asp Displays information about the sample.
AboutPage.asp Displays information about the current page.
BookDetail.asp Displays detailed information about a title.
Cart-Empty.asp Empties the contents of the shopping cart.
Cart-Main.asp Displays the contents of the shopping cart.
CategoryDet.asp Displays detailed information about a category.
CategorySum.asp Displays a summary of all categories.
ChangeTitle.js Updates the title displayed above each page.
CheckOrderStatus.asp Checks the status of prior orders.
Customer.asp Multi-use; creates, modifies and displays customer information.
Default.asp Contains the frameset used to display all other pages.
Home.asp Displays a welcome message, listing of featured titles, new titles, and best sellers.
Menu-Left.asp Provides site menu functionality.
Menu-Top.asp Displays page titles and provides menu functionality for exploring the sample.
Payment.asp Displays complete order and obtains credit card information from customer.
Process.asp Processes the customer’s order and displays resulting message of success or failure.
Shipping.asp Displays shipping options available for shipping the customer’s order.
SignIn.asp Makes it possible for existing customers to identify themselves to the Web site.
TossCookies.asp Removes Online Bookstore cookies from the customer’s computer.
Valiadations.js Provides functions used in validating data provided in forms.
ViewSource.asp Displays the ASP source used to generate the current page.

Walk-Through

To get a feel for the application, you can walk through it as if you were a new customer purchasing a book and checking on the order status of your new order.

Step One: Enter Web Site

First, the new customer points a Web browser to the Online Bookstore Web site. The Online Bookstore’s home page is displayed in the customer’s Web browser.

Figure 1. Online Bookstore Web site

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the entry page of the Web site from the customer’s Web browser.
  • The default page for this site is Default.asp, which contains an HTML frameset that is made up of three frames. Two of the frames serve as menus, providing functionality available throughout the entire Web site. The main frame displays pages that provide the bulk of the customer’s experience. When entering the Web site, this frame contains a page called Home.asp.
  • When Home.asp is processed by IIS, a check is made to see if the user is a returning customer. If so, a customized greeting is displayed; otherwise, a standard greeting is displayed.
  • Instances of objects are created in the business layer to process requests for featured titles, new titles, and best sellers.
  • Using ADO, these objects call stored procedures in SQL Server using the OLE DB Provider for SQL Server.
  • The returned data is used to compose HTML-formatted table rows that are used to construct the resulting page.
  • IIS sends the generated HTML to the customer’s Web browser.

Step Two: Create New Account

When the customer clicks the new account button in the left frame, a form for creating a new account is displayed in the customer’s browser.

Figure 2. New account form

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the new account page from the customer’s Web browser.
  • When Customer.asp was requested, a parameter was passed indicating that the context of the Customer.asp request is to create a new customer.
  • Based on this parameter, a blank form is created to request the information for creating an account from the new customer.
  • IIS sends the generated HTML to the customer’s Web browser.

Step Three: Review Saved Information

When the new customer completes the form and clicks Save to process the form, the customer’s information is displayed with a confirmation message.

Figure 3. Viewing saved information

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the customer page from the customer’s Web browser.
  • When Customer.asp was requested, a parameter was passed indicating that the context of the Customer.asp request is to save a new customer’s information.
  • Instances of objects are created in the business layer to create the new customer account.
  • Using ADO, these objects generate a SQL INSERT query to create the new user account in the Oracle database using the OLE DB Provider for Oracle.
  • After the customer’s information has been saved, a form, pre-filled with the saved information, is created and a confirmation message is included.
  • IIS sends the generated HTML to the customer’s Web browser.

Step Four: Return to Main Page

Now, the new customer reviews the form and clicks Continue to proceed. The main page of the site now displays with the customer’s name.

Figure 4. Main page with new customer's name displayed

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the entry page of the Web site from the customer’s Web browser.
  • The default page for this site is Default.asp, which contains an HTML frameset that is made up of three frames. Two of the frames serve as menus, providing functionality available throughout the entire Web site. The main frame displays pages that provide the bulk of the customer’s experience. When entering the Web site, this frame contains a page called Home.asp.
  • When Home.asp is processed by IIS, a check is made to see if the user is a returning customer. If so, a customized greeting is displayed; otherwise, a standard greeting is displayed.
  • Instances of objects are created in the business layer to process requests for featured titles, new titles, and best sellers.
  • Using ADO, these objects call stored procedures in SQL Server using the OLE DB Provider for SQL Server.
  • The returned data is used to compose HTML-formatted table rows that are used to construct the resulting page.
  • IIS sends the generated HTML to the customer’s Web browser.

Step Five: View Book Details

When a title from the “Today’s Top Sellers” list is selected, a page with detailed information is displayed.

Figure 5. Book details

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the book detail page from the customer’s Web browser.
  • When BookDetail.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • Using ADO, the current inventory of the title is requested from the DB2 database through the OLE DB Provider for DB2. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the DB2 database. DB2 processes the request and returns the requested data.
  • Using ADO, detailed title information is requested through the OLE DB Provider for SQL Server from SQL Server using a stored procedure.
  • The data is combined to create a completed page that is sent to the customer’s Web browser.

Step Six: View Shopping Cart

The customer reviews the information about the selected title and decides to purchase this book. A page displaying the contents of the shopping cart, which now contains the selected title, is shown.

Figure 6. Viewing shopping cart contents

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for adding the book to the customer’s shopping cart.
  • When Cart-Main.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • Using ADO, the customer’s current shipping address is obtained from an Oracle database with a query passed through the OLE DB Provider for Oracle.
  • Using ADO, the current inventory of the title is requested from the DB2 database through the OLE DB Provider for DB2. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the DB2 database. DB2 processes the request and returns the requested data.
  • Using ADO, detailed title information is requested through the OLE DB Provider for SQL Server from SQL Server using a stored procedure.
  • The data is combined to create a completed page that is sent to the customer’s Web browser.

Step Seven: Select Shipping Method

To start the checkout process, the customer clicks checkout. A page showing the available shipping options is shown first.

Figure 7. Selecting shipping method

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the book detail page from the customer’s Web browser.
  • When Shipping.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • Using ADO, information regarding shipping options is requested from keyed physical files on an AS/400 through the OLE DB Provider for AS/400 and VSAM. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the AS/400. Information from the AS/400 files is returned to the business objects.
  • The data is used to construct a completed page that is sent to the requesting Web browser.

Step Eight: Provide Payment Information

The customer selects overnight delivery and clicks Next. The next page displays the completed order with a computed total cost, and requests information about the credit card to be used to pay for the purchase.

Figure 8. Payment information

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the book detail page from the customer’s Web browser.
  • When Payment.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • Using ADO, information regarding the selected shipping method is requested from keyed, physical files on an AS/400 through the OLE DB Provider for AS/400 and VSAM. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the AS/400. Information from the AS/400 files is returned to the business objects.
  • Using ADO, the current inventory of the title is requested from the DB2 database through the OLE DB Provider for DB2. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the DB2 database. DB2 processes the request and returns the requested data.
  • Using ADO, detailed title information is requested through the OLE DB Provider for SQL Server from SQL Server using a stored procedure.
  • The data is used to construct a completed page with a form requesting credit card information, which is sent to the customer’s Web browser.

Step Nine: Order Processed

When the customer is satisfied with the order, clicking Order Now is required to complete the order. A confirmation page displays an order number and other related information.

Figure 9. Order processed

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the book detail page from the customer’s Web browser.
  • When Process.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • An object in the business layer makes a method call for requesting credit card approval that corresponds to a CICS program on a mainframe. Using COMTI, this request passes through SNA Server, which provides the SNA LU6.2 connection to the mainframe. At the mainframe, CSMI (the transaction processor for the remote environment on the mainframe) gets control and makes the request to the CICS program. The CICS program processes the request and returns either an approval or disapproval.
  • Using ADO, an order record is inserted in the DB2 database through the OLE DB Provider for DB2. The provider passes the INSERT query through SNA Server, which provides the SNA LU6.2 connection to the DB2 database.
  • Using ADO, the current inventory of the title is debited in the DB2 database through the OLE DB Provider for DB2. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the DB2 database. DB2 processes the request and returns the requested data.
  • Using ADO, an order detail record is inserted in the DB2 database through the OLE DB Provider for DB2. The provider passes the INSERT query through SNA Server, which provides the SNA LU6.2 connection to the DB2 database.
  • Based on the outcome, a result message is included in the response page, which is sent to the customer’s Web browser.

Step Ten: Review Order Status

If the customer decides to check on the order status by clicking order status, a page is displayed with the current status of the pending order.

Figure 10. Reviewing order status

Background

Behind the scenes, the following steps are taking place:

  • IIS receives and processes the request for displaying the book detail page from the customer’s Web browser.
  • When CheckOrderStatus.asp is requested, instances of objects are created in the business layer to process requests for the information.
  • Using ADO, the customer’s ID is requested from the Oracle database using the OLE DB Provider for Oracle.
  • Using ADO, the customer’s ID is used to obtain the customer’s orders from the DB2 database using the OLE DB Provider for DB2. The provider passes the request through SNA Server, which provides the SNA LU6.2 connection to the DB2 database. DB2 processes the request and returns the requested data.
  • Using ADO, a stored procedure is called on SQL Server through the OLE DB Provider for SQL Server for each order. This stored procedure uses the Distributed Query Processor to return data from a linked server (DB2 using the OLE DB Provider for DB2) and SQL Server. This data constitutes the order details for a given order.
  • The data is used to construct a completed page displaying the customer’s orders, including order details, and the current status of each order, which is sent to the customer’s Web browser.
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