EGL Sequential File Access

1. EGL Sequential File Access This section describes how to access serial (sequential) files from a program. It assumes you understand EGL projects, the language, tools and build-files.

2. Sequential File I/O- Using a Program to Write to a Sequential File  Let’s say that you want to write a program that reads your relational database, processed rows, and writes out an external file (like a report or some other batch process). Here are the steps: • Create a batch program to write to a sequential file • Create a new record of type: serialRecord – which contains a reference to a logical name associated with an external file • Write EGL logic to read and/or write to an external file • Modify the project default Build file. Add a new resource association part • Add an Association element for the external file • Logical (internal) name • File type • (Physical) file name/file spec • Specify for the project default Build file the option to point to the new Resource Association for the external file • Debug or Run the batch program • From the above you can see that much of the work revolves around modifying the project Build Descriptor file. • Up to now we’ve barely used it for anything! That is about to change, but first we’ll create a new batch EGL program.

3.  Sequential File I/O– New Program – 1 of 2 • From Project Explorer, create a new standalone EGL program, in the \programs\ folder, named: fileWriter • Add two records as shown here (note copy/paste code from the Notes section of the slides) • Serial record – to access a sequential file • Basic record – just for more practice  • Press Ctrl/S – and remove any EGL syntax errors

4.  Sequential File I/O– New Program – 2 of 2 Add the following business logic  • By copying all of the code from the Notes section of the slide… and replacing all of the code in your new fileWriter program • Press Ctrl/S - and remove any errors • Press Ctrl/G – to generate Java for the program Notes: endOfFile is an EGL reserved word that you can think of as an “enumerated condition” – like an “88-level” in COBOL When the actual end-of-file (past last record of the file) condition happens, the endOfFile condition will be true.

5.  Add a new Resource Association – 1 of 3 Here are the steps: 1. (From Window menu) Select Show View > Outline 2. (From Project Explorer) Open batchBuildfile.eglbld 3. (From the Outline view) Right click over batchBuild.eglbld - and select: • Add Part... From add EGL Build Part select:  Resource Associations • Click Next > From Resource Associations Part specify: • Name: resAssociation • Click Finish

6.  Add a new Association to the Resource Association – 2 of 3 Add a new Association: - Click Add Association - (Re)Name the file: custFile - Select: System: win File Type: seqws - Specify the systemName c:\customerData.dat - Select text: YES • Press Ctrl/S Note: if pointing systemName to a directory, it must already exist

7.  Add the Resource Association to the Build file – 3 of 3  Select: batchBuild file.eglbld • Uncheck Show only specified options and find the resourceAssociations option • Using the drop-down select: resAssociation • Press Ctrl/S

8.  Debug the Program  From Project Explorer: • Open fileWriter.egl and add some break-points • Right-click over fileWriter.egl and select: Debug EGL Program • Respond OK to all database prompts. • Verify your work: • Follow the logic • View the variable • values

9.  Verify the External Data File  From Windows Explorer – or My Computer, open: c:\customerData.dat