Sun Java System Portal Server 7.1 Developer's Guide

Chapter 26 About the RDM API

This chapter

Introduction to the RDM API

This chapter describes the use of the search engine Resource Description Manager (RDM) API to access the search engine and its database. The RDM API provides routines to parse, modify, and create resource description messages (RDMs) using C.

The robot generates RDs and saves them to the search engine database. You can retrieve the RDs in Search format, use the RDM API to modify them, and then have the search engine import them back.

The RDM API is defined in the rdm.h file in the following directory in your search engine installation directory:

PortalServer-base/sdk/rdm/include

This chapter is restricted to discussing the use of C functions that come with the search engine RDM API. Therefore, it is strongly recommended that you have a basic understanding of the C programming language.

`rdm.h` File

The file rdm.h defines structures and functions for creating RDMs. The intent of these functions is to construct queries and instructions that can be output as RDM and sent via the sendrdm program to a search engine for processing. These queries and instructions are created in the C programming language.

The basic structures are:

RDMHeader
RDMQuery

To support each of these main structures, there are additional structures like RDMViewAttributes, RDMViewOrder, and RDMViewHit which are used to represent attributes in an RDMQuery.

The RDM API defined in rdm.h file provides functions for creating and modifying these structures. For example, the following statement:

RDMQuery *myquery = RDMQuery_Create("varrius");

creates an RDMQuery that corresponds to the following Search:

@RDMQUERY { -
    scope{7}:varrius
}

The following statement:

RDMQuery_SetViewAttr(myquery, "URL,Title");

modifies the RDMQuery so that it corresponds to the following Search:

@RDMQUERY { -
    scope{7}:varrius
    view-attributes{30}: URL,Title,Author,Last-Modified
}

Both the RDMHeader and RDMQuery structures have search fields, which contain the Search data for the header or the query. To extract Search data from RDMHeader or RDMQuery, you can access the search field. Thus, you can also use the RDM Search API to create and modify RDMHeader and RDMQuery objects.

API Reference

This section describes the RDM API, located in directory PortalServer-base/sdk/rdm/include/rdm.h.

Finding the RDM Version

RDM_Version

NSAPI_PUBLIC const char *RDM_Version(void);

Returns the version of the RDM library.

Creating and Freeing RDM Structures

For most RDMX structures, such as RDMRequest, RDMQuery, and so on, there are two or more creation functions. There is usually an RDMX_Parse() function, which takes Search arguments, and an RDMX_Create() function, which takes non-Search arguments.

There is also an RDMX_Free() function, which releases the object.

Several RDM structures also have an RDMX_merge() function, which merges data from a Search object into an existing RDMX structure.

An `RDMHeader`

An RDMHeader represents the header of an RDM. An RDMHeader structure has one public field, Search, which is a Search containing a collection of attribute-value pairs. The allowable attribute names of the attribute-value pairs in the Search are:

rdm-version (required) - This is set automatically if you use RDMHeader_CreateRequest() or RDMHeader_CreateResponse() to create the RDMHeader.
rdm-type (required).
catalog-service-id (recommended) - This indicates which search engine instance to send the RDM request to).
rdm-query-language (required for a request) - For communicating with the search engine, you can specify search.

Response RDMs also have several attributes, and you can find them in rdm.h.

The following statements create an RDMHeader whose RDMType is RDM_RD_REQ, and whose query language is search. This RDM will be sent to the search engine instance search1 of the search engine at http://budgie.siroe.com:6714.

CSID *csid = CSID_Parse("x-catalog://budgie.siroe.com:6714/search1");
RDMHeader *myheader = RDMHeader_CreateRequest(RDM_RD_REQ, "search", csid);

The allowable values for RDM-Type and their description are:

RDM_MSGTYPE_UNKNOWN: Undefined or unknown message type
RDM_RD_UPD_REQ: Requesting an RD update
RDM_RD_REQ: Requesting an RD update (same as RDM_RD_UPD_REQ)
RDM_RD_DEL_REQ: Requesting an RD delete
RDM_RD_UPD_RES: Responding to an RD update request
RDM_RD_RES: Responding to an RD update request (same as RDM_RD_UPD_RES)
RDM_RD_DEL_RES: Responding to an RD delete request
RDM_SD_REQ: Requesting a server description
RDM_SD_RES: Responding to a server description request
RDM_SCH_REQ: Requesting a schema description
RDM_SCH_RES: Responding to a schema description request
RDM_TAX_REQ: Requesting a taxonomy description
RDM_TAX_RES: Responding to a taxonomy description request
RDM_STAT_REQ: Requesting a status
RDM_STAT_RES: Responding to a status description request

You can use the following macros to get and set the string values of the attributes:

RDMHeader_GetType(RDMHeader) /* returns RDMType */
RDMHeader_GetVersion(RDMHeader)
RDMHeader_GetQueryLanguage(RDMHeader)
RDMHeader_GetCSID(RDMHeader)
RDMHeader_GetResponseInterpret(RDMHeader)
RDMHeader_GetErrorMessage(RDMHeader)
RDMHeader_GetErrorNumber(RDMHeader)

RDMHeader_SetType(RDMHeader,RDMType)
RDMHeader_SetVersion(RDMHeader,stringvalue)
RDMHeader_SetQueryLanguage(RDMHeader,stringvalue)
RDMHeader_SetCSID(RDMHeader,stringvalue)
RDMHeader_SetResponseInterpret(RDMHeader,stringvalue)
RDMHeader_SetErrorMessage(RDMHeader,stringvalue)
RDMHeader_SetErrorNumber(RDMHeader,stringvalue)

`RDMHeader_Parse`	NSAPI_PUBLIC RDMHeader RDMHeader_Parse (SearchStream ss);
`RDMHeader_Create`	NSAPI_PUBLIC RDMHeader *RDMHeader_Create(RDMType t);
`RDMHeader_CreateRequest`	NSAPI_PUBLIC RDMHeader RDMHeader_CreateRequest (RDMType, char ql, CSID *)
`RDMHeader_CreateResponse`	NSAPI_PUBLIC RDMHeader RDMHeader_CreateResponse (RDMType, char ri, CSID *);
`RDMHeader_Free`	NSAPI_PUBLIC int RDMHeader_Free(RDMHeader *r);
`RDMHeader_Merge`	NSAPI_PUBLIC int RDMHeader_Merge(RDMHeader , Search ) Merges data from a Search object into the RDMHeader object.

An `RDMQuery`

An RDMQuery represents the body of an RDM. An RDMQuery structure has one public field, search, which is a Search containing a collection of attribute-value pairs. The allowable attribute names of the attribute-value pairs in the Search are:

scope (required)
view-attributes (optional)
view-hit (optional)
view-order (optional)
view-template (optional)

You can use the following macros to get and set the string values of these attributes:

RDMQuery_GetScope(query)
RDMQuery_GetViewAttr(query)
RDMQuery_GetViewHits(query)
RDMQuery_GetViewOrder(query)
RDMQuery_GetViewTemplate(query)

RDMQuery_SetScope(query, value)
RDMQuery_SetViewAttr(query,value-list)
RDMQuery_SetViewHits(query,value)
RDMQuery_SetViewOrder(query,value-list)
RDMQuery_SetViewTemplate(query,value)

`RDMQuery_Parse`	NSAPI_PUBLIC RDMQuery RDMQuery_Parse(SearchStream ss);
`RDMQuery_Create`	NSAPI_PUBLIC RDMQuery RDMQuery_Create(const char scope);
`RDMQuery_Free`	NSAPI_PUBLIC int RDMQuery_Free(RDMQuery *);
`RDMQuery_Merge`	NSAPI_PUBLIC int RDMQuery_Merge(RDMQuery , Search );

Other RDM Structures

In addition to RDMHeader and RDMQuery, the file rdm.h provides definitions and functions for the following auxiliary objects. See the rdm.h file in PortalServer-base/sdk/rdm/include directory for details.

RDMRequest
RDMResponse
RDMServer
RDMView
RDMViewHits
RDMViewOrder
RDMTaxonomy
RDMClassification
RDMSchema