This tutorial shows how to create a COBOL Web application project and how to make it interact with an existing COBOL program. The project includes a page that is generated in managed COBOL. The page calls an intermediary program to map .NET data types onto COBOL data types. The intermediary program then calls the existing COBOL program to perform the business logic.
The Web application project has three programs:
The first task is to create a Web Application Project, which you do as follows:
This creates the BookDemoWebApplication project, which is shown in the Solution Explorer. The project includes:
You now need to add the existing COBOL code that contains the business logic, so that the form can use it. This code is supplied in a LegacyBook project containing book.cbl.
In addition, you need some wrapper code to convert the data from .NET types to COBOL types. The project uses .NET data types; these are System.String objects in our case. The book program uses COBOL types such as PIC X and PIC 99V99. The supplied program BookWrapper.cbl does this conversion, and you need to add this to the solution.
The supplied files are in the %PUBLIC%\Documents\Micro Focus\Enterprise Developer\Samples and in the Forms subfolder.
To include dependant code in your Web application project, you need to add a reference to the code in your solution as follows:
You now need to add some code to the form to call the wrapper code:
01 my-book type BookWrapper.Book.
You should have no parsing errors, now that BookWrapper is declared. If you do have errors, check the supplied demonstration in the Forms\BookDemoWebApplication subfolder of the Samples to see where yours differs.
<!--The following code declares a section group for application configuration --> <configSections> <sectionGroup name="MicroFocus.COBOL.Application"> <section name="Switches" type="System.Configuration.NameValueSectionHandler" /> <section name="Environment" type="System.Configuration.NameValueSectionHandler" /> </sectionGroup> <sectionGroup name="MicroFocus.COBOL.Runtime"> <section name="Tunables" type="System.Configuration.NameValueSectionHandler" /> <section name="Switches" type="System.Configuration.NameValueSectionHandler" /> </sectionGroup> </configSections>
In the Web.config file, add the following text immediately after the </configSections> line:
<MicroFocus.COBOL.Application> <Switches/> <Environment> <add key="dd_bookfile" value="MyPath\bookfile.dat"/> </Environment> </MicroFocus.COBOL.Application>
Where you need to replace MyPath with the full path to the data file bookfile.dat, which is in the BookData subfolder in the Samples directory.
In this section, you paint the form. You can also examine the code generated. For basic help on painting a form, see the tutorial Tutorial: Developing .NET COBOL Applications.
To lay out the Web form, use spaces and new lines, in the same way as you do in a text editor or in HTML.
To view the properties of a control, click the control in the designer and view its properties in the Properties pane. You can then scroll to the relevant property and edit it.
Double-clicking a control creates an event for the control, which we don't want to do till the next step. Edit the properties to the following values:Control | ID Property | Text Property |
---|---|---|
Label | label1 | CATALOG SEARCH |
Label | catalogNumberLabel | Catalog Number |
TextBox | textBoxStockNo (the case is significant) | (blank) |
Button | searchButton | Search |
Label | errorLabel | File Status |
TextBox | errorField | (blank) |
Label | label2 | RESULTS |
Label | titleLabel | Title |
TextBox | textBoxTitle (the case is significant) | (blank) |
Label | authorLabel | Author |
TextBox | textBoxAuthor | (blank) |
Label | typeLabel | Type |
TextBox | textBoxType | (blank) |
Label | priceLabel | Price |
TextBox | textBoxPrice (the case is significant) | (blank) |
Label | soldLabel | Sold |
TextBox | textBoxSold | (blank) |
Label | onHandLabel | On Hand |
TextBox | textBoxOnhand | (blank) |
Label | stockValueLabel | Stock Value |
TextBox | textBoxStockValue | (blank) |
Now you need to add the code for the button click, which needs to call the legacy COBOL program and to populate the form with the information returned.
method-id searchButton_Click protected. working-storage section. 01 aBook type BookWrapper.Book. 01 anException type System.Exception. local-storage section. procedure division using by value lnkSender as object by value lnkEvent as type EventArgs. try set aBook to type BookWrapper.Book::Read(textBoxStockNo::Text) invoke self::PopulateForm(aBook) catch anException invoke self::DisplayException(anException) end-try end method.
method-id PopulateForm final private. procedure division using aBook as type BookWrapper.Book. if aBook <> null set errorLabel::Visible to false set errorField::Visible to false set textBoxStockNo::Text to aBook::StockNumber set textBoxTitle::Text to aBook::Title set textBoxAuthor::Text to aBook::Author set textBoxType::Text to aBook::Type set textBoxPrice::Text to type System.Convert::ToString(aBook::RetailPrice) set textBoxOnhand::Text to type System.Convert::ToString(aBook::NumberOnHand) set textBoxSold::Text to type System.Convert::ToString(aBook::NumberSold) set textBoxStockValue::Text to type System.Convert::ToString(aBook::StockValue) else set textBoxStockNo::Text to "****" set textBoxTitle::Text to "*************************************" set textBoxAuthor::Text to "*************************************" set textBoxType::Text to "****" set textBoxPrice::Text to "****" set textBoxOnhand::Text to "****" set textBoxSold::Text to "****" end-if end method.
method-id DisplayException private. procedure division using by value lnkException as type System.Exception. set my-book to null set errorLabel::Visible to true set errorField::Visible to true set errorField::Text to lnkException::Message invoke self::PopulateForm(my-book) end method.
If there were any problems with running this demonstration, you can compare your application with the same sample available in the Samples folder.
The book.cbl program is a long-standing demonstration program that has been shipped with Micro Focus products for several years. It is written in procedural COBOL. The program reads and writes to an indexed file containing book records.
In this solution, the Book program is recompiled to managed code without any changes. Recompiling the program exposes it as a class and exposes its main entry point as a static method.
The program's Linkage section defines data as standard COBOL types, such as PIC X, which non-COBOL client programs will not understand. These types need to be mapped to .NET compatible types before communication with the client program. This mapping is done by the intermediary program BookWrapper.cbl.
The client Web form Default.aspx.cbl is generated as COBOL. The user enters data into the form and receives the return data there. The client form does the following:
The BookWrapper.cbl program acts as an intermediary between the pre-existing COBOL program book.cbl and the Web form. This enables you to leave the pre-existing COBOL unchanged.
The important point here is that you need to use compatible types when mixing languages. The Web form stores the data as .NET types and yet the Book program expects data as COBOL types.
The purpose of the BookWrapper program is to map your COBOL PICTUREs to .NET System.Strings. The program receives data from the Web form as System.Strings, and maps them onto standard COBOL data types before passing them to the pre-existing book program.
The working storage declares the data items in a book record by using a copybook, as follows:
working-storage section. copy "book-rec-dotnet.cpy" replacing == (prefix) == by == book ==. ...
The copybook book-rec-dotnet.cpy declares the book-details record. It declares book-title and book-stockno as COBOL pictures and also as properties so that Getter/Setter methods can be used to access them. The copybook contains:
01 (prefix)-details. 03 (prefix)-text-details. 05 (prefix)-title pic x(50) property as "Title". ... 03 (prefix)-stockno pic x(4) property as "StockNumber".
The following property method gets a pointer to the book-details record:
property-id BookDetails pointer. getter. set property-value to address of book-details end property.
The Read method is implemented as follows:
method-id Read static. local-storage section. 01 file-status pic xx. procedure division using by value stockno-in as string returning myBook as type BookWrapper.Book. set myBook to new BookWrapper.Book() set myBook::StockNumber to stockno-in call "BookLegacy" using by value readRecord by value myBook::BookDetails by reference file-status invoke self:RaiseExceptionIfError(file-status) goback. end method.
procedure division using ...
shows a .NET System.String, stockno-in, being passed in from client form. It also shows an instance of the Book class being returned. BookWrapper.cbl defines a new .NET type, Book, which can be used by programs written in any .NET language.
set myBook to new BookWrapper.Book()
set mybook::StockNumber
takes the data from the .NET System.String (stockno-in) and stores it as the StockNumber property of myBook. This property is declared in the copybook as a picture string, and so the data is stored as a standard COBOL data type in book-stockno. The COBOL Compiler implicitly converts the data from the .NET string into a COBOL usage display item (pic x).
call BookLegacy using ...
calls the legacy program, book.cbl. It passes it the “BookDetails” property of myBook. If you look at the code in BookWrapper.cbl, you can see that what BookDetails does is pass a pointer to the BookRecord structure defined in book-rec-net.cpy. This structure matches the structure in the old book-rec.cpy, so what the legacy Book program sees is a book record being passed in by reference – which is what it expects. Book reads the stock number from this record, reads a record from the indexed file, and then puts the data in the other fields of the record.
invoke self::RaiseExceptionIfError(file-status)
checks the file status returned from reading the file, and raises a .NET exception if there was an error. Exceptions are the standard .NET mechanism for signaling error conditions.