SlimDAO
Instead of using a static object relational database mapping, MIB Explorer uses its own lightweight and easy configurable database mapping mechanism called SlimDAO.
Basically a SlimDAO DB mapping configuration file contains SQL statements and their fragments in an XML file. Because the SQL dialects of different databases often differ only for special statements, like sequence and constraint creation, SlimDAO supports statement inheritance.
A SQL statement (or a complete script) can be defined in the default context „.“ and overwritten in a specific context whose name matches the JDBC driver class name for the database whose SQL dialect differs from the default context‘s dialect (e.g., org.postgresql.Driver for a PostgreSQL database).
Each statement and script in the mapping configuration has a unique name within its context. MIB Explorer will lookup a statement by its name. The name is hard-coded. The supported statement names are defined by the default context in the Monitor2DB.xml file from the db-monitor directory.
A statement is defined for example by the following construct:
| Code Block |
|---|
<statement name="select.monitor.by.id">
SELECT * FROM @INSERT[SCHEMA].MXP_MONITOR
WHERE ID = @VALUE[ID]
</statement>
|
During runtime, MIB Explorer uses the statement to get monitor data from the database. It replaces the constructs of the pattern
| Code Block |
|---|
@<TAG>[<PARAM_LIST>]
|
with the corresponding values as described by the table following this section. The resulting SQL statement would then be executed on the DB server as follows:
| Code Block |
|---|
SELECT * FROM MXP.MXP_MONITOR WHERE ID = ?
|
The question mark ? is a placeholder for the value within the prepared statement. The value will be inserted by the JDBC driver when the prepared statement is being executed. MIB Explorer sets the value for the statement by replacing the @VALUE[ID] reference with the ? in the statement and setting the statements first parameter value to the value of ID (for example 2).
Tag | Description |
|---|
@VALUE[<param>]
| Replace the tag by
Example:? in the statement and set the value of the prepared parameter to the value of the MIB Explorer variable with name <param>. | Code Block |
|---|
SELECT ID FROM MXP.MXP_MONITOR WHERE NAME = @VALUE\[NAME\] |
will be rendered to | Code Block |
|---|
SELECT ID FROM MXP.MXP_MONITOR WHERE NAME = ? |
where ? is assigned with the value of the MIB Explorer variable NAME when the statement is being executed. |
@INSERT[<param>]
| Replace the tag by the value of MIB Explorer variable with name <param>
Example: | Code Block |
|---|
SELECT ID FROM MXP.MXP_MONITOR WHERE NAME = '@INSERT[NAME]' |
will be rendered to | Code Block |
|---|
SELECT ID FROM MXP.MXP_MONITOR WHERE NAME = 'MyMonitor' |
if the variable NAME has the string value MyMonitor. |
@USE[<statementName>]
| Replace the tag with the rendered content of the statement with name <statementName> of the same context.
Example: | Code Block |
|---|
<statement name="select.id"> \\
SELECT ID \\
</statement> \\
<statement name="select.monitor.id.by.name"> \\
@USE[select.id] FROM MXP.MXP_MONITOR WHERE NAME = @VALUE[NAME] \\
</statement> |
will be rendered to | Code Block |
|---|
SELECT ID FROM MXP.MXP_MONITOR WHERE NAME = 'MyMonitor' |
if the variable NAME has the string value MyMonitor. |
@IF[<stmt>,<test>,<value>,..]
| Replace the tag with the statement with name <stmt> if the condition <test> is true for the MIB Explorer variable references <value1> through <valueN>.
Example: | Code Block |
|---|
<statement name="monitor.dataset.by.id"> \\
SELECT * FROM MXP.MXP_MONITORDATASET WHERE MONITOR_ID = @VALUE\[ID\] \\
@IF\[and.nameOrDataType,not-null,NAME,DATATYPE\] \\
ORDER BY MONITOR_ID,DATATYPE \\
</statement> \\
<statement name="and.nameOrDataType"> \\
AND (NAME = @VALUE\[NAME\] OR DATATYPE = @VALUE\[DATATYPE\]) \\
</statement> |
will be rendered to | Code Block |
|---|
SELECT * FROM MXP.MXP_MONITORDATASET WHERE MONITOR_ID = ? AND (NAME = ? OR DATATYPE = ?) ORDER BY MONITOR_ID,DATATYPE |
if the MIB Explorer variables NAME and DATATYPE are not null. |
@IFELSE[<stmtTrue>, <stmtFalse>,<test>, <value>..]
| Replace the tag with the statement with name <stmtTrue> if the condition <test> is true for the MIB Explorer variable references <value1> through <valueN>. Otherwise, replace the tag with the statement with name <stmtFalse>.
Example: | Code Block |
|---|
<statement name="monitor.dataset.by.id"> \\
SELECT * FROM MXP.MXP_MONITORDATASET WHERE MONITOR_ID = @VALUE\[ID\] \\
@IFELSE\[dataTypeNotNull,dataTypeNull,not-null,DATATYPE\] \\
</statement> \\
<statement name="dataTypeNull"> \\
AND DATATYPE IS NULL \\
</statement> \\
<statement name="dataTypeNotNull"> \\
AND DATATYPE IS NOT NULL \\
</statement> |
will be rendered to | Code Block |
|---|
SELECT * FROM MXP.MXP_MONITORDATASET WHERE MONITOR_ID = ? AND DATATYPE IS NOT NULL |
if the MIB Explorer variables DATATYPE is not null. Otherwise, the statement would be rendered as: | Code Block |
|---|
SELECT * FROM MXP.MXP_MONITORDATASET WHERE MONITOR_ID = ? AND DATATYPE IS NULL |
|
The tags @IF and @IFELSE insert a statement depending on the truth of a condition. The supported condition rules are listed by the following table.
Test Condition | Description |
|---|
exists
| Is true if all parameters exists. A parameter value might still be null though. |
not-exists
| Is true if at least one of the parameters does not exists. |
is-null
| Is true if at least one parameter is null or does not exists. |
not-null
| Is true if all parameters are not null and exist. |
=
| Is true if all parameters are equal to the first parameter. |
!=
| Is true if all parameters (starting from the second one) are not equal to the first parameter. |
<
| Is true if the first parameter is less than all the following parameters. |
>
| Is true if the first parameter is greater than all the following parameters. |
<=
| Is true if the first parameter is less or equal than all the following parameters. |
>=
| Is true if the first parameter is greater or equal than all the following parameters. |