naveenprasathc / iso8583lib

C++ library to work with Iso8583 messages

Iso8583lib

C++ library to work with Iso8583 messages. Since I didn't find many "generic" solutions in C++ I decided to give it a shot and try to implement one.

This is a work in progress.

Basic concepts

This library aims at providing the basic skeletons and functionality over which different adaptations of the Iso8583 messages can be implemented, leaving thus the developer only with the task of filling in the details that are specific to the particular messages she's working with.

There are 3 main abstractions to work with: the fields, their format and the message. The gist of each of them is explained in the following subsections.

Field formats

The field format determines what characters are allowed in a particular field, what padding (left or right) should they have and what character should be used for the padding. There is a convenience macro in include/IsoType.hpp to facilitate the creation of field format specifiers.

Data fields

An Iso8583 message can contain up to 128 data fields or data elements. The standard is not always respected and is not unusual to find tailored implementations of the standard in which a data element was customized to fit a particular need. Iso8583lib tries to cover (many of) the different cases that can be found out there by means of the small class hierarchy defined in include/DataElement.hpp. There is an abstract base class called DataElementBase which defines an interface common to all the data fields. From there, 3 subclasses deal with possibly the most common scenarios (they can always be extended if needed):

• DataElement: it's a class template that represents a simple data element, e.g. a seller's name. The allowed values as well as the format it has are determined by the IsoType that is used as a template argument.
• DataElementComposite: a common customization is to divide a particular data field into sub-fields to store data in an aggregated fashion. The composite data element as its name indicates basically does this.
• DataElementDecorator: another common customization is to arbitrarily prefix the value from a data field with some special identifier as a way of extending the functionality of the given data element. The abstract data element decorator class wraps a DataElementBase and allows to apply any kind of decoration to it.

Message

The Iso8583 message consists of a 4 digit message identifier, 1 or 2 bitmaps and a set of data fields. The class template from include/IsoMessage.hpp coordinates all that. The template parameter has to be a Data Element Factory which will typically allow to create data elements by means of their id. This makes the message class flexible since it only has to coordinate the reading or writing of the message and leave the details of the format of the data elements to the factory.

Examples

Please, refer to the examples folder to see a toy example.

Requirements

The only requirement is C++14.

TODO's

There are at least some features missing:

• Currently there's no enforcement over the DataElements that are part of a particular message. That could be achieved with a message factory.
• Similarly, the validation done on the message type identifier is quite lax right now. A message factory would also help with this.
• There's no character encoding handling.

Author

Esteban Campostrini