Write RESTful Services in C

You can write REST as well as SOAP web services using Apache Axis2/C web services framework. There you can make existing Axis2/C web services RESTful just by providing the URL patterns and the HTTP methods to each operation in  the services.xml which act as a simple descriptor for an Axis2/C service.

So if we rewrite the RESTful Demo (Written in PHP) using Axis2/C, the services.xml would be something like following.

<service name="RESTfulSchool">
    <!-- mentioning the service library-->
    <parameter name="ServiceClass" locked="xsd:false">RESTfulSchool</parameter>

    <!-- some description -->
    <description>
        The RESTful School demo
    </description>

    <!-- list of operations -->
    <operation name="getSubjects">
            <parameter name="RESTMethod">GET</parameter>
            <parameter name="RESTLocation">subjects</parameter>
    </operation>
    <operation name="getSubjectInfoPerName">
            <parameter name="RESTMethod">GET</parameter>
            <parameter name="RESTLocation">subjects/{name}</parameter>
    </operation>
    <operation name="getStudents">
            <parameter name="RESTMethod">GET</parameter>
            <parameter name="RESTLocation">students</parameter>
    </operation>
    <operation name="getStudentInfoPerName">
            <parameter name="RESTMethod">GET</parameter>
            <parameter name="RESTLocation">students/{name}</parameter>
    </operation>
    <operation name="getMarksPerSubjectPerStudent">
            <parameter name="RESTMethod">GET</parameter>
            <parameter name="RESTLocation">students/{student}/marks/{subject}</parameter>
    </operation>
</service>

We will check how to write the service logic for a operation like “getMarksPerSubjectPerStudent”.

axiom_node_t *
RESTfulSchool_getMarksPerSubjectPerStudent(
    const axutil_env_t * env,
    axiom_node_t * request_payload)
{
    axiom_node_t *student_node = NULL;
    axiom_node_t *subject_node = NULL;

    /* Extracting out the child nodes from the request */
    student_node = axiom_node_get_first_child(request_payload, env);
    subject_node = axiom_node_get_next_sibling(student_node, env);

    /* now we can write the logic to retrieve the marks
       for the given student and subject and build and
       return the response payload */

    return response_payload;
}

As you can see the variables {student} and {subject} given in the services.xml can be easily accessed from your business logic, so we can build the response accordingly.

This way you can build a RESTful web services easily using C language.