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DataAccess COM library can used by any COM-compliant program to read Cobol data files.
Simple API allows you to quickly develop applications that read Cobol data directly,
Features
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Directness and Simplicity.
You interface to Cobol data files directly, without extra layers of ODBC and OLE DB.
This simplifies programming a lot.
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Speed.
Since we access data files directly (no ODBC / OLE DB in between), the library is really fast.
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Versatility.
Our data model accurately reflects what is available in Cobol data file -- not more, not less.
So your program can read Cobol data files using all "native" Cobol abilities with "native" speed.
For inastance, fast reading by any index or combination of indices is provided.
Download Evaluation
The examples used in User Manual are in VB, so start with downloading and installing
DataViewer Trial Package that contains API samples.
Please note that you can use DataAccessCOM in any COM-enabled language (C++, Delphi, Access, not just VB).
You will return here after the download.
DataAccessCOM Manual
Download it from DataAccessManual.doc.
DataAccessCOM Introduction
Below we provide an introduction to DataAccessCOM API.
Formal description of DataAccessCOM API is contained in comaccess.idl file.
DataFile.
To start using API, create DataFile object:
Dim reader As DataFile
Set reader = New DataFile
Open file using Open function.
You must open an *.FDD file that contains record layout and a link to the actual data file.
Do not open the data file itself.
If file cannot be opened, error is returned, you can check specific error code in Err.Number.
reader.Open ("filename.fdd")
Use function ReadNext() to read next record into DataRecord object
contained in DataFile.
You will access record fields through DataRecord object.
reader.ReadNext()
Dim record As DataRecord
Set record = reader.Record
Summary of all file operations:
reader.Open(
BSTR file_name) ' open specified file
reader.Close() ' close opened file
reader.GotoTop() ' go to first record of the file
reader.GotoBottom() ' go to last record of the file
reader.ReadNext() ' read next record into reader.Record
reader.ReadPrev() ' read previous record: REL only
reader.ReadByRecNumber( ' read record by record number: REL only
long rec_number)
reader.RecCount() ' number of records in the file: REL only
reader.ReadByIndex( ' read record by specified index: INDEX only
long index_number,
bool from_beg)
reader.IndicesNo() ' number of indices in the file: INDEX only
reader.IndexInUse( ' index used for sequential reads: INDEX only
long index_number)
DataRecord.
To browse fields of the data record, use FieldsNo and Item methods:
Dim record As DataRecord
Set record = reader.Record
Dim i As Integer
For i = 0 To record.FieldsNo - 1
Dim field As DataField
Set field = record.Item(i)
Next
Summary of all record methods:
print record.FieldsNo() ' number of fields in the record
print record.Item(int index) ' get field by its index
print record.Item(BSTR name) ' get field by its name
print record.Blob() ' raw array of bytes for the record
print record.ByteMinLength() ' minimum record length
print record.ByteMaxLength() ' maximum record length
DataField.
DataRecord is a collection of DataFields.
Each DataField represents a single record field.
Once you get down to the field, you can extract all its properties including name and value.
Dim field As DataField
Set field = record.Item(i)
Set field = record.Item("field-name")
print field.Name() ' field name, as specified in RDD file
print field.Value() ' field value: VARIANT, can be: Integer, Float, Date
print field.Blob() ' raw array of bytes for the field
print field.ByteOffset() ' offset of field in the raw record
print field.ByteLength() ' length of field in the raw record
print field.Length() ' length of field when printed out
print field.Decimals() ' position of the decimal point
print field.Type() ' Modern type of the field: Int, Fixed, String, Float, Date-Time
print field.Picture() ' PICTURE of the field
print field.Usage() ' USAGE of the field: DISPLAY, COMP-1, ..., COMP-X
print field.Sign() ' SIGN of the field: LEAD, LEAD SEP, TRAIL, TRAIL SEP
print field.Alphabet() ' ALPHABET of the field: ASCII, EBCDIC, Japanese
Property field.Blob() returns array of bytes that are actually stored in the field.
This is raw uninterpreted field.
Licensing DataAccessCOM
If you plan to use DataAcessCOM internally on Four (4) computers or less, then you need
DataAccessCOM Non-Redistributable License that is included into
Data-Viewer package.
If you want to distribute application that use DataAccessCOM then
you need DataAccessCOM Redistributable license.
Please contact us for details.
Evaluation Package: More Languages
The example presented in different languages does the following:
* Print the list of fields,
* Print first 10 records of the data file specified by user,
* Prints the list of indices in the data file,
* Reads records by indices.
Visual Basic.
* Start the project from "Start. Programs. Siber DataViewer. COM API Samples in VB".
* Add DataAccessCOM to References:
-- Open Project. References,
-- Check Siber Systems DataAccess Type Library.
C++.
* Start the project from "Start. Programs. Siber DataViewer. COM API Samples in C++".
* Since dataaccesscom.dll was registered at install time, there is no need to register it again.
* Just compile and run the example.
Delphi.
* Start Delphi.
* Install package DataAccess.dpk.
* Open project "Project1.dpr".
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