Contents
JsonCBR (Json Content Based Routing) is used to route the incoming messages on to different destinations based on the content of the messages. The component creates a port for each of the JsonPath expressions specified and the messages satisfying the particular JsonPath expression is sent onto the respective port. In addition to these ports an output port OUT_FALSE is created and messages whose content does not satisfy any of the JsonPath expressions will be sent out of this port. If more than one JsonPath expression is true, the message is sent on all the ports for which the JsonPath expression evaluates to true.
Configuration and Testing
The JsonCBR component can be configured using its Custom Property Sheet wizard.
Figure 1: JsonPath(s) to be evaluated on the input messages
JsonPath
JsonPaths based on which the routing is done can be configured in JsonCBR Configuration Page.A valid JsonPath expression can be typed directly in the table.
An empty row is automatically added after pressing Enter key after the JsonPath is manually provided.
For each configured JsonPath expression, an output port is created with the name provided in Port Name column, messages satisfying the given Json Objects condition are routed onto this port. Port names ON_EXCEPTION and OUT_FALSE are reserved and cannot be set in Port Name column.
JsonPath contains the path of any element, then JsonCBR checks for the existence of the particular element in the input Json Object. If the input JsonObject contains the element then it will be routed to the corresponding output port of that JsonPath, if the input JsonObject does not contain the element then it will be routed to the output port OUT_FALSE.
- Json values which are passsed in input Json object should only be any of these types : Long, Integer, Double, String, Boolean, BigInteger, BigDecimal
Comparison of the JSONPath syntax elements with its XPath counterparts.
| XPath | JSONPath | Description |
|---|---|---|
| / | $ | the root object/element |
| .. | n/a | parent operator |
| // | .. | |
| | | [,] | Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set. |
| n/a | [start:end:step] | array slice operator borrowed from ES4. |
| [] | ?() | applies a filter (script) expression. |
| n/a | () | script expression, using the underlying script engine. |
| () | n/a | grouping in Xpath |
Operators
This field includes boolean operators like ==, !=, <, >, <=, >=, EXISTS, NONEXISTENT.
- The EXISTS operator return true if given JsonPath exists.
- While NONEXISTENT operator returns true when given JsonPath is nonexistent.
Value
This field includes Long, Integer, Double, String, Boolean, BigInteger, BigDecimal, and JsonPath. If a "$" precedes any value, then it is treated as a JsonPath. In this case the values of the two JsonPaths are compared for evaluating the expression.
Functional Demonstration
Scenario
JsonCBR is configured to filter the messages on the basis of book price in the input message. It is sent to one of the output ports depending on the JsonPath specified in the JsonCBR CPS.
Configure the JsonCBR as described in Configuration and Testing section and use feeder and display component to send sample input and check the response respectively.
Figure2: Demonstrating the Scenario with sample input and output
Sample Input
Sample Output
JsonOutput5 : As $.store.book[0].price is 8.95 which is less than 18.4, hence the following output.
JsonOuptput4: As $.store.book[1].title is "Sword of Honour", which is not equals to "abc", hence the following output.
JsonOuptput3: As $.store.book[2].category is "fiction", which is equal to $.store.book[1].category, hence the following output.
JsonOuptput2: As $.store.book[0].isbn does not exist, hence no output.
JsonOuptput1: As some Json expressions were evaluated as true so the FALSE_PORT gets no output, hence no output is displayed.
Error: The errors that were generated while evaluating the Json expression are displayed here like- invalid json format etc.