Objective: Introduction to the dblookup mediatorDemonstrate simple database read operations using the DBLookup mediator.
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<definitions xmlns="http://ws.apache.org/ns/synapse">
<sequence name="myFaultHandler">
<makefault>
<code value="tns:Receiver" xmlns:tns="http://www.w3.org/2003/05/soap-envelope"/>
<reason expression="get-property('ERROR_MESSAGE')"/>
</makefault>
<property name="RESPONSE" value="true"/>
<header name="To" expression="get-property('ReplyTo')"/>
<send/>
<drop/>
</sequence>
<sequence name="main" onError="myFaultHandler">
<in>
<log level="custom">
<property name="text"
value="** Looking up from the Database **"/>
</log>
<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" type="VARCHAR"/>
<result name="company_id" column="id"/>
</statement>
</dblookup>
<switch source="get-property('company_id')">
<case regex="c1">
<log level="custom">
<property name="text"
expression="fn:concat('Company ID - ',get-property('company_id'))"/>
</log>
<send>
<endpoint>
<address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
</endpoint>
</send>
</case>
<case regex="c2">
<log level="custom">
<property name="text"
expression="fn:concat('Company ID - ',get-property('company_id'))"/>
</log>
<send>
<endpoint>
<address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
</endpoint>
</send>
</case>
<case regex="c3">
<log level="custom">
<property name="text"
expression="fn:concat('Company ID - ',get-property('company_id'))"/>
</log>
<send>
<endpoint>
<address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
</endpoint>
</send>
</case>
<default>
<log level="custom">
<property name="text" value="** Unrecognized Company ID **"/>
</log>
<makefault>
<code value="tns:Receiver"
xmlns:tns="http://www.w3.org/2003/05/soap-envelope"/>
<reason value="** Unrecognized Company ID **"/>
</makefault>
<property name="RESPONSE" value="true"/>
<header name="To" action="remove"/>
<send/>
<drop/>
</default>
</switch>
<drop/>
</in>
<out>
<send/>
</out>
</sequence>
</definitions> |
...
This sample demonstrates simple database read operations through the ESB. When a message arrives at dblookup the DBLookup mediator, it opens a connection to the database and executes the SQL query. The SQL query use uses the '?' character for attributes that will be filled at runtime. The , and the parameters define how to calculate the value of those attributes at runtime. In this sample, a dblookup DBLookup mediator has been used to extract the 'id' of the company from the company database using the symbol which that is evaluated using an xpath XPath against the SOAP envelope. Then 'id' base switching will be done by a switch Switch mediator.
When the IBM stock quote is requested ,as follows:
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ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=IBM |
The ESB console shows:
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INFO LogMediator text = ** Looking up from the Database **INFO LogMediator text = Company ID ? c1 |
For the SUN stock quote,:
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ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=SUN |
The ESB console shows:
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INFO LogMediator text = ** Looking up from the Database **INFO LogMediator text = Company ID ? c2 |
and for the MSFT stock quote,:
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ant stockquote -Daddurl=http://localhost:9000/services/SimpleStockQuoteService -Dtrpurl=http://localhost:8280/ -Dsymbol=MSFT INFO LogMediator text = ** Looking up from the Database ** INFO LogMediator text = Company ID ? c2 |
For any other symbols, the ESB console shows:
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INFO LogMediator text = ** Unrecognized Company ID ** |
and the client gets a response which has with the following message.
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** Unrecognized Company ID ** |