Networking Reference
In-Depth Information
Table 5.1 EMML commands
￿
Data consumption
-While
-Invoke
-For
- Direct Invoke
- Foreach
- Input
- Parallel
- Output
- Sequence
￿
Data transformation ( mashup)
￿
Macros
- Filter
- Macro
- Join
- Include
-Merge
￿
Debug
- Select
- Group
- Display
￿
Data enrichment
￿
Transactions
- Append
- SQL
- Constructor
- SQL Update
- Annotate
- Begin TX
- Assign
- Commit TX
- Variable
- Rollback TX
￿ Operations for control logics and error handling
￿ Meta operations
- If-else
- Template UserMeta
The capabilities of EMML can be broadly classified into sets of operations, as
listed in Table 5.1 . The following paragraphs illustrate the operation of some of these
EMML programming elements. The complete EMML reference can be found in [ 4 ].
The
< directinvoke >
EMML element is used to invoke and consume diferent
types
of
services
such
as: HTML, RSS/ATOM, REST and SOAP.
The
element supports HTTP verbs GET, POST, PUT, and
DELETE. HTTP Header and cookie support is also available, thus providing capa-
bility to consume a wide variety of Web services. Figure 5.2 shows an example of the
usage of the
< directinvoke >
< directinvoke >
element. In this Figure, the endpoint specifies the
URL of the service to be consumed; u and f are the input parameters of the service;
and outputvariable specifies the variable that will receive the result of the service
invocation.
The
element allows filtering a set of nodes in a variable, based on a
filter expression. In Fig. 5.3 , inputvariable provides the data input to the filter; filter-
< filter >
Fig. 5.2 Usage example of
<
directinvoke
>
element
 
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