This chapter describes how to use Oracle WebLogic Tuxedo Connector VIEW buffers.
This chapter includes the following sections:
Note:
For more information on Oracle Tuxedo VIEW buffers, see "Using a VIEW Typed Buffer" in Programming a Tuxedo ATMI Application Using C athttp://download.oracle.com/docs/cd/E13203_01/tuxedo/tux100/pgc/pgbuf.html.Oracle WebLogic Tuxedo Connector allows you to create a Java VIEW buffer type analogous to an Oracle Tuxedo VIEW buffer type derived from an independent C structure. This allows Oracle WebLogic Server applications and Oracle Tuxedo applications to pass information using a common structure. Oracle WebLogic Tuxedo Connector VIEW buffers do not support FML VIEWs or FML VIEWs/Java conversions.
Note:
fbname and null fields are not relevant for independent Java and C structures and are ignored by the Java and C VIEW compiler. You must include a value (for example, a dash) as a placeholder in these fields.Your Oracle WebLogic Server application and your Oracle Tuxedo application must share the same information structure as defined by the VIEW description. The following format is used for each structure in the VIEW description file:
$ /* VIEW structure */ VIEW viewname type cname fbname count flag size null
where
The file name is the same as the VIEW name.
You can have only one VIEW description per file.
The VIEW description file is the same file used for both the Oracle WebLogic Tuxedo Connector viewj compiler and the Oracle Tuxedo viewc compiler.
viewname is the name of the information structure.
You can include a comment line by prefixing it with the # or $ character.
The following table describes the fields that must be specified in the VIEW description file for each structure.
Table 8-1 VIEW Description File Fields
| Field | Description |
|---|---|
type
|
Data type of the field. Can be set to |
cname
|
Name of the field as it appears in the information structure. |
fbname
|
Ignored. |
count |
Number of times field occurs. |
flag |
Specifies any of the following optional flag settings:
|
size |
For |
null |
User-specified NULL value, or minus sign ( The default NULL value for all numeric types is 0 (0.0 for dec_t). For character types, the default NULL value is ` Constants used, by convention, as escape characters can also be used to specify a NULL value. The VIEW compiler recognizes the following escape constants: \ddd (where d is an octal digit), \0, \n, \t, \v, \r, \f, \\, \', and \". You may enclose STRING, CARRAY, and char NULL values in double or single quotes. The VIEW compiler does not accept unescaped quotes within a user-specified NULL value. You can also specify the keyword NONE in the NULL field of a VIEW member description, which means that there is no NULL value for the member. The maximum size of default values for string and character array members is 2660 characters. |
The following provides an example VIEW description which uses VIEW buffers to send information to and receive information from an Oracle Tuxedo application. The file name for this VIEW is infoenc.
Example 8-1 Example VIEW Description
VIEW infoenc #type cname fbname count flag size null float amount AMOUNT 2 - - 0.0 short status STATUS 2 - - 0 int term TERM 2 - - 0 char mychar MYCHAR 2 - - - string name NAME 1 - 16 - carray carray1 CARRAY1 1 - 10 - dec_t decimal DECIMAL 1 - 9 - #size ignored by viewj/viewj32 END
To compile a VIEW typed buffer, run the viewj command, specifying the package name and the name of the VIEW description file as arguments. The output file is written to the current directory.
To use the viewj compiler, enter the following command:
java weblogic.wtc.jatmi.viewj [options] [package] viewfile
To use the viewj32 compiler, enter the following command:
java weblogic.wtc.jatmi.viewj32 [options] [package] viewfile
The arguments for this command are defined as follows:
| Argument | Description |
|---|---|
| options |
Note: |
package |
The package name to be included in the .java source file.
Example: examples.wtc.atmi.simpview |
viewfile |
Name of the VIEW description file.
Example: |
For example:
A VIEW buffer is compiled as follows:
java weblogic.wtc.jatmi.viewj -compat_names examples.wtc.atmi.simpview infoenc
A VIEW32 buffer is compiled as follows:
java weblogic.wtc.jatmi.viewj32 -compat_names -modify_strings examples.wtc.atmi.simpview infoenc
The output of the viewj and viewj32 command is a .java source file that contains set and get accessor methods for each field in the VIEW description file. Use these set and get accessor methods in your Java applications to pass information to and from a VIEW buffer.
The AssociatedFieldHandling flag is used to specify if the set and get methods use the values of the associated length and count fields if they are specified in the VIEW description file.
set methods set the count for an array field and set the length for a string or carray field.
Array get methods return an array that is at most the size of the associated count field.
String and carray get methods return data that is at most the length of the associated length field.
Use one of the following to set or get the state of the AssociatedFieldHandling flag:
Use the -associated_fields option for the viewj and viewj32 compiler to set the AssociatedFieldHandling flag to true.
Invoke the void setAssociatedFieldHandling(boolean state) method in your Java application to set the state of the AssociatedFieldHandling flag.
If false, the set and get methods ignore the length and count fields.
If true, the set and get methods use the values of the associated length and count fields if they are specified in the VIEW description file.
The default state is false.
Invoke the boolean getAssociatedFieldHandling() method in your Java application to return the current state of AssociatedFieldHandling.
Use the following steps when incorporating VIEW buffers in your JATMI applications:
Create a VIEW description file for your application as described in How to Create a VIEW Description File.
Compile the VIEW description file as described in How to Use the viewj Compiler.
Use the set and get accessor methods to pass information to and receive information from a VIEW buffer as described in How to Pass Information to and from a VIEW Buffer.
See the examples/wtc/atmi/simpview/ViewClient.java file in your Oracle WebLogic Server distribution for an example of how a client uses accessors to pass information to and from a VIEW buffer.
Import the output of the VIEW compiler into your source code.
If necessary, compile the VIEW description file for your Oracle Tuxedo application and include the output in your C source file as described in "Using a VIEW Typed Buffer" in Programming a Tuxedo ATMI Application Using C at http://download.oracle.com/docs/cd/E13203_01/tuxedo/tux100/pgc/pgbuf.html.
Configure a WTCServer MBean with a Resources Mbean that specifies the VIEW buffer type (VIEW or VIEW32) and the fully qualified class name of the compiled Java VIEW description file. The class of the compiled Java VIEW description file should be in your CLASSPATH.
Build and launch your Oracle Tuxedo application.
Build and launch your Oracle WebLogic Server Application.
A helper class is available to add and get VIEW32 data in and out of an FML32 buffer. The class name is wtc.jatmi.FViewFld. This class assists programmers in developing JATMI-based applications that use VIEW32 field type for FML32 buffers.
No change to configuration is required. You still configure the VIEW32 class path using the ViewTbl32Classes attribute in the WTCResources section of the WLS configuration file.
The following access methods are available in this helper class.
FViewFld(String vname, TypedView32 vdata);
FviewFld(FviewFld to_b_clone);
void setViewName(String vname)
String getViewName();
void setViewData(TypedView32 vdata)
void TypedView32 getViewData();
Example 8-2 How to Add and Retrieve an Embedded TypedView32 buffer in a TypedFML32 Buffer
String toConvert = new String("hello world");
TypedFML32 MyData = new TypedFML32(new MyFieldTable());
Long d1 = new Long(1234);
Float d2 = new Float(12.32);
MyView data = new myView();
FviewFld vfld;
data.setamount((float)100.96);
data.setstatus((short)3);
vfld = new FviewFld("myView", data);
try {
myData.Fchg(MyFieldTable.FLD0, 0, toConvert);
myData.Fchg(MyFieldTable.FLD1, 0, 1234);
myData.Fchg(MyFieldTable.FLD2, 0, d2);
myData.Fchg(MyFieldTable.myview, 0, vfld);
} catch (Ferror fe) {
log("An error occurred putting data into the FML32 buffer. The error is " + fe);
}
try {
myRtn = myTux.tpcall("FMLVIEW", myData, 0);
} catch(TPReplyException tre) {
….
}
TypedFML32 myDataBack = (TypedFML32)myRtn.getReplyBuffer();
Integer myNewLong;
Float myNewFloat;
myView View;
String myNewString;
try {
myNewString = (String)myDataBack.Fget(MyFieldTable.FLD0, 0);
myNewLong = (Integer)myDataBack.Fget(MyFieldTable.FLD1, 0);
myNewFloat = (Float)myDataBack.Fget(MyFieldTable.FLD2, 0);
vfld = (FviewFld)myDataBack.Fget(MyFieldTable.myview, 0);
view = (myView)vfld.getViewData();
} catch (Ferror fe) {
….
}
The following code listing is an example FML Description(MyFieldTable) related to the example in Example 8-2.
*base 20000 #name number type flags comments FLD0 10 string - - FLD1 20 long - - FLD2 30 float - - myview 50 view32 - defined in View description file
Use the XmlViewCnv class to perform XML to View /View(32) or View/View(32) to XML translation. The following code listing is an example that uses the XmlViewCnv class for conversion to and from XML buffer formats.
import examples.wtc.atmi.simpview.infoenc; // View class import
weblogic.wtc.gwt.XmlViewCnv;
import weblogic.wtc.jatmi.TypedBuffer;
public class xml2view
{
public static void main(String[] args) {
String xmlDoc =
"<VIEW32><infoenc><amount>1000.0</amount><infoenc></VIEW32>";
infoenc convertMe = new infoenc();
convertMe = (infoenc) XmlViewCnv.XMLToView(
xmlDoc,
convertMe.getClass(),
convertMe.getSubtype());
convertMe = (infoenc) echo.Echo(convertMe);
result = XmlViewCnv.ViewToXML(
(TypedBuffer) convertMe,
convertMe.getClass(),
true);
System.out.println(result);
}
}