eSuite and Data Access
Lotus eSuite provides developers with powerful ways to access legacy data and use it in applications created with eSuite applets.
The eSuite DBMS access architecture makes use of the InfoBus features and offers a highly flexible model for connecting to a variety of data types. The eSuite data access applets are based on SQL/JDBC and CGI technologies. Adherence to these standards enables eSuite applets to interact with DBMSs from IBM, Oracle, Microsoft and others. These applets have no user interface and can be programmed by the developer to provide the presentation applets with information from a back-end information source.
The main components of the eSuite data access story are the following applets:
The JdbcSource applet accesses external data in the following ways:
- Reads data from external databases
- Sends modifications to data in external databases
- Publishes query results on the InfoBus to make the data accessible to other applets
Once the JdbcSource applet loads a JDBC driver and connects to an external database, multiple retrieval and modify operations may be performed on the database. Query execution is controlled by an incoming "trigger" data items arriving from the InfoBus. Queries can be parameterized by additional items read from the InfoBus. JdbcSource uses the Java Data Base Connectivity (JDBC) framework to connect to external data sources.
The CGI gateway applet lets you handle application data in the following ways:
- Acts as an interface between the InfoBus and the server program that collects data from the Infobus
- Sends data to the server and places the server's output back on the InfoBus for consumption by other eSuite applets
- Eases the use of CGI-compliant server programs, such as HTML fill-in-form processors
Data is read from the InfoBus according to a description suplied to the CGI gateway applet via HTML parameters. The description contains the names of the data sets to watch for (or, alternately, lists the actual data). Data returned from the server is then presented to the InfoBus or, optionally, displayed as HTML in the browser.
The FormReader and TableReader applets are "Infobus-aware" data access applets that read the contents of a form or table within an HTML document. The contents are then posted to the InfoBus.
By default, these applets do the following when accessing HTML form or table data:
- accesses an HTML document from the provided URL
- parses the document for the occurence of form or table data
- extracts the data from the HTML form or table
- places the contents of the form or table on the InfoBus as data that can be used by other applications
These applets are derived from the HTMLReaderApplet class, which uses the ParseHTML class to process the HTML.
The FileReader applet does the following:
- Publishes an 8-bit ASCII sequential file to the InfoBus as a data item of type ArrayAccess
- Lets you specify the input file name and the output data item name as PARAM tags
for the applet