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Table of Contents

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Syntax

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Localtabgroup

Localtab

active	true
title	Connection Pool

Code Block

	XML
	XML

<DBLookup><dblookup>
   <connection>
      <pool>
        <driver/>
        <url/>
        <user/>
        <password/>
        <property name="name" value="value"/>*
      </pool>
   </connection>
   <statement>
      <sql>select something from table where something_else = ?</sql>
      <parameter [value="" | expression=""] type="CHAR|VARCHAR|LONGVARCHAR|NUMERIC|DECIMAL|BIT|TINYINT|SMALLINT|INTEGER|BIGINT|REAL|FLOAT|DOUBLE|DATE|TIME|TIMESTAMP"/>*
      <result name="string" column="int|string"/>*
   </statement>+
</DBLookup>dblookup>

Localtab

title	Data source

The syntax of the DBLookup mediator further differs based on whether the connection to the database is made using an external datasource or a Carbon datasource. Click on the relevant tab to view the required syntax.

Localtabgroup

Localtab

title	External Datasource

Code Block

	XML
	XML

<DBLookup><dblookup>
   <connection>
      <pool>
        <dsName/>
        <icClass/>
        <url/>
        <user/>
        <password/>
        <property name="name" value="value"/>*
      </pool>
   </connection>
   <statement>
      <sql>select something from table where something_else = ?</sql>
      <parameter [value="" | expression=""] type="CHAR|VARCHAR|LONGVARCHAR|NUMERIC|DECIMAL|BIT|TINYINT|SMALLINT|INTEGER|BIGINT|REAL|FLOAT|DOUBLE|DATE|TIME|TIMESTAMP"/>*
      <result name="string" column="int|string"/>*
   </statement>+
</DBLookup>dblookup>

Localtab

title	Carbon Datasource

Code Block

	XML
	XML

<DBLookup><dblookup>
   <connection>
      <pool>
        <dsName/>
      </pool>
   </connection>
   <statement>
      <sql>select something from table where something_else = ?</sql>
      <parameter [value="" | expression=""] type="CHAR|VARCHAR|LONGVARCHAR|NUMERIC|DECIMAL|BIT|TINYINT|SMALLINT|INTEGER|BIGINT|REAL|FLOAT|DOUBLE|DATE|TIME|TIMESTAMP"/>*
      <result name="string" column="int|string"/>*
   </statement>+
</DBLookup>dblookup>

...

UI Configuration

The UI configuration of the DBLookup mediator changes depending on whether you connect to the database using a connection pool, or using a data source. Click on the relevant tab to view the required UI configuration.

Localtabgroup

The maximum number of milliseconds that the connection pool will wait for a connection to

Localtab

active	true
title	Connection Pool

The parameters available to configure the DBLookup mediator are as follows:

Parameter Name	Description
Connection Information	This parameter is used to specify whether the connection should be taken from a connection pool or a datasource.


Driver	The class name of the database driver.
URL	JDBC URL of the database where the data will be looked up.
User	Username used to connect to the database.
Password	Password used to connect to the database.

Adding properties to the DBLookup mediator

If you click Add Property, the page will expand to display the following parameters.

The parameters available to manage properties are as follows.

Parameter Name	Description
Name	The name of the property.
Value	The value of the property.
Action	This parameter enables a property to be deleted.

The available properties are as follows.

Name	Value	Description
autocommit	true / false	The auto-commit state of the connections created by the pool.
isolation	Connection.TRANSACTION_NONE / Connection.TRANSACTION_READ_COMMITTED / Connection.TRANSACTION_READ_UNCOMMITTED / Connection.TRANSACTION_REPEATABLE_READ / Connection.TRANSACTION_SERIALIZABLE	The isolation state of the connections created by the pool.
initialsize	int	The initial number of connections created when the pool is started.
maxactive	int	The maximum number of active connections that can be allocated from this pool at a given time. When this maximum limit is reached, no more active connections will be created by the connection pool. Specify 0 or a negative value if you do not want to set a limit.
maxidle	int	The maximum number of idle connections

to be

allowed in the connection pool at a given time.

Specify 0 or a negative value if you want the pool to wait indefinitely.

maxopenstatements

int

The maximum number of open statements that can be allocated from the statement pool at a given time. When this maximum limit is reached, no more new statements will be created by the statement pool. Specify 0 or a negative value if you do not want to set a limit.

maxwait

long

The value should be less than the maxActive value. For high performance, tune maxIdle to match the number of average, concurrent requests to the pool. If this value is set to a large value, the pool will contain unnecessary idle connections.

Info
The enabled idle connections are checked periodically whenever a new connection is requested, and connections that are being idle for longer than `minEvictableIdleTimeMillis` are released, since it takes time to create a new connection.

maxopenstatements

int

The maximum number of open statements that can be allocated from the statement pool at a given time. When this maximum limit is reached, no more new statements will be created by the statement pool. Specify 0 or a negative value if you do not want to set a limit.

maxwait

long

The maximum number of milliseconds that the connection pool will wait for a connection to return before throwing an exception when there are no connections available in the pool. Specify 0 or a negative value if you want the pool to wait indefinitely.

minidle

int

The minimum number of idle connections allowed in the connection pool at a given time, without extra ones being created. Default value is 0, and is derived from initialSize. The connection pool can shrink below this number if validation queries fail.

Info
This value should be similar or near to

be allowed in the connection pool at a given time. Specify 0 or a negative value if you want the pool to wait indefinitely

the average number of requests that will be received by the server at the same time. With this setting, you can avoid having to open and close new connections every time a request is received by the server.

poolstatements

true/ false

If the value is true, statement pooling is enabled for the pool.

testonborrow

true/ false

If the value is true, objects are validated before they are borrowed from the pool. An object which fails the validation test will be dropped from the pool and another object in the pool will be picked instead.

testwhileidle

true/ false

If the value is true, the objects in the pool will be validated using an idle object evictor (if any exists). Any object which fails this validation test would be dropped from the pool.

validationquery

String

The SQL query that will be used to validate connections from this pool before returning them to the caller.

Localtab

title	Data source

The UI configuration of the DBLookup mediator further differs based on whether the connection to the database is made using an external datasource or a Carbon datasource. Click on the relevant tab to view the required UI configuration.

Localtabgroup

Localtab

title	External Datasource

The parameters available to configure the DBLookup mediator are as follows.

Parameter Name	Description
Connection Information	This parameter is used to specify whether the connection should be taken from a connection pool or a datasource.
Datasource Type	This parameter is used to specify whether the connection to the databased should be made using an external datasource or a Carbon datasource.
Initial Context	The initial context factory class. The corresponding `Java` environment property is `java.naming.factory.initial`.
Datasource Name	The naming service provider URL . The corresponding `Java` environment property is `java.naming.provider.url`.
URL	JDBC URL of the database that data will be looked up from.
User	The user name used to connect to the database.
Password	The password used to connect to the database.

Adding properties to the DBLookup mediator

If you click Add Property, the page will expand to display the following parameters.

The parameters available to manage properties are as follows.

Parameter Name	Description
Name	The name of the property.
Value	The value of the property.
Action	This parameter enables a property to be deleted.

The available properties are as follows.

Name	Value	Description
autocommit	true / false	The auto-commit state of the connections created by the pool.
isolation	Connection.TRANSACTION_NONE / Connection.TRANSACTION_READ_COMMITTED / Connection.TRANSACTION_READ_UNCOMMITTED / Connection.TRANSACTION_REPEATABLE_READ / Connection.TRANSACTION_SERIALIZABLE	The isolation state of the connections created by the pool.
initialsize	int	The initial number of connections created when the pool is started.
maxactive	int	The maximum number of active connections that can be allocated from this pool at a given time. When this maximum limit is reached, no more active connections will be created by the connection pool. Specify 0 or a negative value if you do not want to set a limit.
maxidle	int	The maximum number of idle connections to be allowed in the connection pool at a given time. Specify 0 or a negative value if you want the pool to wait indefinitely.
maxopenstatements	int	The maximum number of open statements that can be allocated from the statement pool at a given time. When this maximum limit is reached, no more new statements will be created by the statement pool. Specify 0 or a negative value if you do not want to set a limit.
maxwait	long	The maximum number of milliseconds that the connection pool will wait for a connection to return before throwing an exception when there are no connections available in the pool. Specify 0 or a negative value if you want the pool to wait indefinitely.
minidle	int	The minimum number of idle connections to be allowed in the connection pool at a given time. Specify 0 or a negative value if you want the pool to wait indefinitely.
poolstatements	true/ false	If the value is `true`, statement pooling is enabled for the pool.
testonborrow	true/ false	If the value is `true`, objects are validated before they are borrowed from the pool. An object which fails the validation test will be dropped from the pool and another object in the pool will be picked instead.
testwhileidle	true/ false	If the value is `true`, the objects in the pool will be validated using an idle object evictor (if any exists). Any object which fails this validation test would be dropped from the pool.
validationquery	String	The SQL query that will be used to validate connections from this pool before returning them to the caller.

Localtab

title	Carbon Datasource

The parameters available to configure the DBLookup mediator are as follows.

Parameter Name	Description
Connection Information	This parameter is used to specify whether the connection should be taken from a connection pool or a datasource.
Datasource Type	This parameter is used to specify whether the connection to the databased should be made using an external datasource or a Carbon datasource.
JNDI Name	The JNDI used to look up data. See Configuring a JNDI Datasource for more information.

Adding SQL statements to the DBLookup Mediator

Anchor

	SQL Statements
	SQL Statements

If you click Add Statement, the page will be expanded to display the following parameters.

Parameter Name

Description

SQL

This parameter is used to enter one or more SQL statements.

Parameters

This section is used to specify how the values of parameters in the SQL will be determined. A parameter value can be static or calculated at runtime based on a given expression.

Parameter Type

The data type of the parameter. Possible values are as follows.

CHAR
VARCHAR
LONGVARCHAR
NUMERIC
DECIMAL
BIT
TINYINT
SAMLLINT
INTEGER
BIGINT
REAL
DOUBLE
DATE
TIME
TIMESTAMP

Property Type

This determines whether the parameter value should be a static value or calculated at run time via an expression.

Value: If this is selected, a static value would be considered as the property value and this value should be entered in the Value/Expression parameter.
Expression: If this is selected, the property value will be determined during mediation by evaluating an expression. This expression should be entered in the Value/Expression parameter.

Value/Expression

This parameter is used to enter the static value or the XPath expression used to determine the property value based on the option you selected for the Property Type parameter.

Info

title	Tip

You can click NameSpaces to add namespaces if you are providing an expression. Then the Namespace Editor panel would appear where you can provide any number of namespace prefixes and URLs used in the XPath expression.

Action

This allows you to delete a parameter.

Results

This section is used to specify how to deal with the rerun result from a Database query execution.

Result Name
Column
Action - Deletes the result.

Info

title	Note

You can configure the mediator using XML. Click switch to source view in the Mediator window.

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Examples

Code Block

	XML
	XML

<DBLookup<dblookup xmlns="http://ws.apache.org/ns/synapse">
    <connection>
        <pool>
            <driver>org.apache.derby.jdbc.ClientDriver</driver>
            <url>jdbc:derby://localhost:1527/esbdb;create=false</url>
            <user>esb</user>
            <password>esb</password>
        </pool>
    </connection>
    <statement>
        <sql>select * from company where name =?</sql>
        <parameter expression="//m0:getQuote/m0:request/m0:symbol"
                   xmlns:m0="http://services.samples/xsd" type="VARCHAR"/>
        <result name="company_id" column="id"/>
    </statement>
</DBLookup>dblookup>

In this example, when a message is received by a proxy service with a DBLookup mediator configuration, it opens a connection to the database and executes the SQL query. The SQL query uses ? character for attributes that will be filled at runtime. The parameters define how to calculate the value of those attributes at runtime. In this sample, the DBLookup Mediator has been used to extract the id of the company from the company database using the symbol which is evaluated using an XPath against the SOAP envelope.

Excerpt

hidden	true

Description of the DBLookup Mediator in WSO2 ESB.

Versions Compared

Old Version 10

New Version Current

Key

Syntax

UI Configuration

Adding properties to the DBLookup mediator

Adding properties to the DBLookup mediator

Examples

Samples