FAQs

The following provides the answers to some frequently asked questions about Verastream Host Integrator:

General Questions

• What is the Verastream Host Integrator Development Kit?

  The Verastream Host Integrator Development Kit provides an innovative approach to host systems integration and re-engineering, which requires no changes to the existing host systems and causes no interruption to the end-user operating environment.

• Which host character sets are supported?

  In the table below, there are pairs of code pages distinguished by Euro support, such as German and German + Euro. The Euro version of each pair reports that there is support for the Euro code page version to the host; the non Euro version can display the Euro, but does not report this to the host.

EBCDIC

Some Thai characters (cent symbol, the split vertical bar, and the IBM not symbol) do not display correctly in Design Tool dialog boxes that display text for patterns or filtered text. These characters can be input via the keyboard and are displayed correctly in the Design Tool terminal window. The Java, COM, and .NET connectors handle these characters correctly.

Modeling

• Is it the connection or the applications that are block mode or character mode?

  A combination of the host and the application it is running dictates block mode versus character mode. VT/ASCII terminals are always character mode. IBM AS/400 terminals, which use the 5250 datastream protocol, and IBM mainframe terminals, which use the 3270 datastream protocol, are typically block mode. HP3000 terminals can be block mode or character mode, but the combination of the host and the host application determine the type of connection that is needed.

• What's the difference between scrolling operations in character mode applications and block mode applications?

  Scrolling operations, such as page up or page down operations, are in no way unique to character mode or block mode applications. They are important for recordsets, but these types of screen constructs exist in all types of host applications that are accessible by Host Integrator. The only difference is that character mode applications require more specific recordset configuration since it is more difficult to determine when the host is finished sending recordset data after a query has been made.

  TIP: Use Model Debug Messages to view the real-time data sent and received from a host.

• Are there any hard coded timeouts in Verastream Host Integrator or should I expect to be able to configure my own timeouts for settings and operations?

  There are no hard-coded timeouts in the Host Integrator system. For example, you can configure timeouts for the host connection, global navigation, and "keep alive" inactivity in the Model Properties dialog box. Under Properties on the Operation tab, you can also configure a timeout for a selected operation. In addition, all of the Host Events commands provide timeout settings. If any timeout occurs in an operation, the whole operation is stopped—there is no "master timeout." For example, if a Host Events command has a timeout of 10 seconds, while an operation has a timeout of 30 seconds, they each get the full extent of their time until they complete or time out. Since there are so many potential timeouts in Host Integrator, and you must adjust them all appropriately.

• How do I make the current entity an alternate entity or error entity?

  See Troubleshooting Error Patterns and Error Entities for more information.

• What is the difference between using the DefaultValue command and the TransmitToAttr command in operations?

  DefaultValue implies that the value argument will only be written if the client has not provided a value already. If the behavior you want is to always transmit the value to the terminal, regardless of the API client code, then use TransmitToAttr.

• What's the difference between error patterns and error entities?

  Error patterns are often host messages that appear on the terminal screen when an error occurs during an attribute write. These types of messages are common when modeling character mode host applications. They cannot be part of an entity signature, but they can be contained in an operation condition. If an entity encounters an error pattern during an operation, a text or an attribute value can be returned. No action can be associated with an error pattern. An error pattern can consist of a particular host message or a non-blank host message.

  Error entities are entities that only appear when a host error occurs. Error entities can be contained in operations destinations, and they can return text or attribute values in an exception. They cannot, however, be valid or intermediate destinations. Error entities should contain operations to move back to a navigable entity. Typically, the operation to move away from an error entity contains the logic to recover from the error, for example, a locked 5250 terminal can be released by pressing the Reset key. An error entity can be as simple as a copy of some other entity, when the host message line is non-blank.

  Error entities typically have an action associated (an operation to get back to a navigable state), while error patterns cannot contain an action. For more detailed information, see Troubleshooting Error Patterns and Error Entities.

• How and when are error patterns detected?

  Error patterns are registered with the Host Integrator Server scanning component when the operation begins. At any time during the operation that a scan is performed (new data from the host is the usual reason a scan is performed), then the operation can trap the error pattern. If the pattern is already present before an operation starts, it would not be recognized.

• What about tables and error entities?

  If you are using procedures, you can add an error entity to your procedure. Defining error entities is not necessary if you've already defined them in your operations.

  Note

  If you insert error entities into your procedures, you will not be able to use the custom error messaging option available when defining error entities within your operation. Instead, you have to define a custom error message within the Procedure Editor. Additionally, the error message feature within the Procedure Editor does not allow you to assign the contents of an attribute to the error message.

• What about tables and error patterns?

  If you are using tables and error patterns, you don't have to modify anything within your procedures.

• How can I fix the trailing spaces problem?

  If you have a procedure that requires that you send data to a numeric field (format: #####.##) and enter the value 6, for example, you may find that the application will not accept your input. Running a trace reveals that instead of sending just “6”, Host Integrator is sending “6” followed by 7 spaces. The spaces are wiping out the 6 and the result is an error.

  On the Attribute Properties tab, clear the Erase to end of attribute check box associated with writes.