Host Access Class Library for Java
This class library presents
a complete object-oriented abstraction of a host session that includes:
reading and writing the host presentation space (screen), enumerating the
fields on the screen, reading the Operator Indicator Area (OIA) for status
information, transferring files, and performing asynchronous notification
of significant events.
The Host Access Class Library (ECL) consists of the classes which are described
briefly in the section below. The Host Access Class Library
Javadoc provides detailed information for each of the classes
below.
The following is a brief overview of the Host Access Class Library classes.
Each class name begins with ECL, for Host Access Class Library.
- ECLConnection
represents the connection information for a session with a particular host
and contains information such as the connection status, the type of connection
(for example, 3270 or 5250), and the name of the session.
- ECLCommNotify
is a notification interface that an application must implement to be notified whenever
a connection is disconnected from or connected to a host. It can be used
to monitor the status of a connection, for example, to take action when
a connection is disconnected unexpectedly.
- ECLErr provides
a method for returning run-time error information from Host Access Class Library
classes. ECLErr is thrown by ECL objects when a problem is encountered.
ECLErr contains the runtime error information and also
provides methods that applications can use for problem
determination so that the appropriate action can be taken.
- ECLField contains
information about a single field on the screen, such as the field attributes,
field color, position on the screen or length. A method is also supplied
to update input fields.
- ECLFieldList
contains a collection of ECLField objects. When the Refresh method is called,
the current host screen is examined, and the list of fields is extracted
and used to build the list of ECLField objects. An application can use
this collection to manage fields without having to build the list itself.
- ECLOIA provides
access to operator status information such as shift indicators, input inhibited
conditions and communications errors.
- ECLOIANotify
is a notification interface that an application must implement to be notified whenever
the OIA is updated.
- ECLPS represents
the presentation space (screen) of a single connection. It contains methods
for obtaining a copy of the screen contents in the form of data planes.
Each plane represents a specific aspect of the presentation space, such
as the text, field attributes and color attributes. Methods are provided
for searching for strings in the presentation space, sending keystrokes
to the host, getting and setting the host cursor position, and many other
functions. Also provided is an ECLFieldList object that can be used to
enumerate the list of fields on the screen.
- ECLPSNotify
is a notification interface that an application must implement to be notified whenever
the host presentation space is updated.
- ECLSession
contains a collection of all the connection-specific objects. ECLSession
can be used to easily create a complete set of objects for a particular
connection. ECLSession inherits from ECLConnection, and it is the only
access point for the methods in ECLConnection.
- ECLXfer initiates
file transfers to or from the host over the connection.
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