| Internet Engineering Task Force | V.P. Prehnal, Ed. |
| Internet-Draft | Faculty of Informatics, Masaryk University |
| Intended status: Standards Track | May 28, 2011 |
| Expires: November 29, 2011 |
Relational Schema Protocol (RSP)
draft-rsp-00
This document specifies the Relational Schema Protocol (RSP). RSP enables loosely coupled applications to share and exchange relational data. It defines fixed message format for an arbitrary relational schema so that the changes in the data schema do not affect the message format. This prevents the interacting applications from having to be reimplemented during the data schema evolvement.
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Widely disparate applications are very often required to share and exchange data from relational data sources. Typically, this is accomplished by passing messages over a shared environment (e.g. computer network, file system, computing memory, etc.) in a well-defined, machine-processable format. In such a case, the data schema is mapped to the message format such that the elements of the message format reflect the relations and their attributes in the data schema. If the data schema is a subject to change, the message format needs to be redefined. As a consequence, all the interacting applications need to be reimplemented. This represents a serious issue for evolving data schemas.
This specification defines a new communication protocol, RSP, for universal relational data exchange. This protocol enables the interacting applications to describe arbitrary relational schema (including the contained data) using a fixed hierarchy of data types. This way, the format of the messages does not need to be redefined when the data schema evolves.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].
The RSP protocol defines three REQUIRED request-response operations (remote procedures) listed below:
The operation behaviors are specified in section 3. The message format of operation requests and responses is defined using the hierarchy of abstract data types in section 2. These abstract data types MAY be serialized in arbitrary serialization format (e.g. XML, JSON, etc.).
This section specifies the data types used in the protocol.
This section specifies the data types shared by multiple operations.
Data type "TableHeader" represents basic metadata of particular data table. Attributes of this data type are specified in Table 1.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| Description | Description of the table for the documentation purposes | string | Zero or one (OPTIONAL) |
| PluralTitle | Plural user-friendly title of the table in the specified language | string | One (REQUIRED) |
| SingularTitle | Singular user-friendly title of the table in the specified language | string | One (REQUIRED) |
| TableName | Unique name of the table within the whole data schema | string | One (REQUIRED) |
Table 1 - Attributes of the "TableHeader" data type
Data type "ArrayOfTableHeader" represents 1-dimensional list of table headers. Attributes of this data type are specified in Table 2.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| TableHeader | Table header (item in the list) | TableHeader, see Table 1 | Zero or one (OPTIONAL) |
Table 2 - Attributes of the "ArrayOfTableHeader" data type
Data type "ArrayOfint" represents 1-dimensional list of integers. Attributes of this data type are specified in Table 3.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| int | Integer number (item in the list) | int | Zero or one (OPTIONAL) |
Table 3 - Attributes of the "ArrayOfint" data type
Data type "Field" represents metadata of particular table column. Attributes of this data type are specified in Table 4.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| DataType | Data type of the column (int, varchar, datetime, ...) | string | One (REQUIRED) |
| Description | Description of the column for the documentation purposes | string | Zero or one (OPTIONAL) |
| ID | Unique identifier of the column within the whole data schema | string | One (REQUIRED) |
| IsAutoGenerated | True if the column is auto-generated (identity) column | boolean | One (REQUIRED) |
| IsDisplayField | True if the column from the joined table should be displayed instead of the foreign key column in the specified table | boolean | One (REQUIRED) |
| IsEditable | True if the data in the column is editable | boolean | One (REQUIRED) |
| IsForeignKey | True if the column is the foreign key | boolean | One (REQUIRED) |
| IsJoined | True if the column is a part of joined table | boolean | One (REQUIRED) |
| IsNullable | True if the column may contain null-values | boolean | One (REQUIRED) |
| IsPrimaryKey | True if the column is a part of the primary key | boolean | One (REQUIRED) |
| MaximumLength | Maximum character length (only for character data types) | long | Zero or one (OPTIONAL) |
| Name | Unique name of the column within its parent table | string | One (REQUIRED) |
| ReferencedField | Unique name of the referenced column within the referenced table (only for foreign key columns) | string | Zero or one (OPTIONAL) |
| ReferencedTable | Unique name of the referenced table (only for foreign key columns) | long | Zero or one (OPTIONAL) |
| Table | Name of the parent table | string | One (REQUIRED) |
| Title | User-friendly title of the column in the specified language | string | One (REQUIRED) |
Table 4 - Attributes of the "Field" data type
Data type "ArrayOfField" represents 1-dimensional list of fields. Attributes of this data type are specified in Table 5.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| int | Field (item in the list) | Field, see Table 4 | Zero or one (OPTIONAL) |
Table 5 - Attributes of the "ArrayOfField" data type
Data type "ArrayOfstring" represents 1-dimensional list of text strings. Attributes of this data type are specified in Table 6.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| string | Text string (item in the list) | string | Zero or one (OPTIONAL) |
Table 6 - Attributes of the "ArrayOfstring" data type
Data type "ArrayOfArrayOfstring" represents 2-dimensional list of text strings. Attributes of this data type are specified in Table 7.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| ArrayOfstring | 1-dimensional array of text strings (item in the list) | ArrayOfstring, see Table 6 | Zero or one (OPTIONAL) |
Table 7 - Attributes of the "ArrayOfArrayOfstring" data type
Data type "Reference" represents metadata of the referencing table. Attributes of this data type are specified in Table 8.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| RedField | Unique name of the referenced column within the referenced table | string | One (REQUIRED) |
| RedTable | Unique name of the referenced table | string | One (REQUIRED) |
| RingField | Unique name of the referencing column within the referencing table | string | One (REQUIRED) |
| RingFieldTitle | User-friendly title of the referencing column in the specified language | string | One (REQUIRED) |
| RingTable | Unique name of the referencing table | string | One (REQUIRED) |
| RingTablePluralTitle | User-friendly plural title of the referencing table in the specified language | string | Zero or one (OPTIONAL) |
Table 8 - Attributes of the "Reference" data type
Data type "ArrayOfReference" represents 1-dimensional list of references. Attributes of this data type are specified in Table 9.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| Reference | Reference (item in the list) | Reference, see Table 8 | Zero or one (OPTIONAL) |
Table 9 - Attributes of the "ArrayOfReference" data type
Data type "Table" represents data and metadata from the particular data table. Attributes of this data type are specified in Table 10.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| Actions | List of granted permissions (actions) for the specified user and table: 1 ~ SELECT, 2 ~ INSERT, 3 ~ UPDATE, 4 ~ DELETE | ArrayOfint, see Table 3 | One (REQUIRED) |
| Fields | List of fields (columns) | ArrayOfField, see Table 5 | One (REQUIRED) |
| Header | Table header | TableHeader, see Table 1 | One (REQUIRED) |
| Items | List of data items (rows) | ArrayOfArrayOfstring, see Table 7 | One (REQUIRED) |
| References | List of references (e.g. list of tables referencing specified table) | ArrayOfReference, see Table 9 | One (REQUIRED) |
Table 10 - Attributes of the "Table" data type
This section specifies the data types for operation requests and responses.
Data type "ReadTableHeadersRequest" defines the "ReadTableHeaders" operation request message format. Attributes of this data type are specified in Table 11.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| UserName | User name | string | One (REQUIRED) |
| Password | Password | string | One (REQUIRED) |
| Language | Preferred localization language for the data schema (ISO 639-1 two-letter code) | string | Zero or one (OPTIONAL) |
Table 11 - Attributes of the "ReadTableHeadersRequest" data type
Data type "ReadTableHeadersResponse" defines the "ReadTableHeaders" operation response message format. Attributes of this data type are specified in Table 12.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| TableHeaders | 1-dimensional list of table headers | ArrayOfTableHeader, see Table 2 | One (REQUIRED) |
Table 12 - Attributes of the "ReadTableHeadersResponse" data type
Data type "ReadTableRequest" defines the "ReadTable" operation request message format. Attributes of this data type are specified in Table 13.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| UserName | User name | string | One (REQUIRED) |
| Password | Password | string | One (REQUIRED) |
| TableName | Unique name of the data table | string | One (REQUIRED) |
| Language | Preferred localization language for the data schema (ISO 639-1 two-letter code) | string | Zero or one (OPTIONAL) |
| Skip | Number of data items (rows) to skip | long | One (REQUIRED) |
| Take | Number of data items (rows) to take (if 0 is specified, all found items are returned) | long | One (REQUIRED) |
| OrderExpression | Defines how the data items should be sorted (ordered) | string | Zero or one (OPTIONAL) |
| FilterExpression | Defines how the data items should be filtered | string | Zero or one (OPTIONAL) |
Table 13 - Attributes of the "ReadTableRequest" data type
Data type "ReadTableResponse" defines the "ReadTable" operation response message format. Attributes of this data type are specified in Table 14.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| TableHeaders | 1-dimensional list of table headers | ArrayOfTableHeader, see Table 2 | One (REQUIRED) |
Table 14 - Attributes of the "ReadTableResponse" data type
Data type "SubmitRequest" defines the "Submit" operation request message format. Attributes of this data type are specified in Table 15.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| UserName | User name | string | One (REQUIRED) |
| Password | Password | string | One (REQUIRED) |
| TableName | Unique name of the data table | string | One (REQUIRED) |
| Operation | Type of submit operation (1 ~ INSERT, 2 ~ UPDATE, 3 ~ DELETE) | int | One (REQUIRED) |
| Fields | List of fields | ArrayOfField, see Table 5 | One (REQUIRED) |
| Data | Data item (table row) to submit. The order of the data values within the item must match the order of appropriate fields in Fields attribute. | ArrayOfstring, see Table 6 | One (REQUIRED) |
Table 15 - Attributes of the "SubmitRequest" data type
Data type "SubmitResponse" defines the "Submit" operation response message format. Attributes of this data type are specified in Table 16.
| Name | Definition | Data Type | Multiplicity |
|---|---|---|---|
| Identity | Identity of the new data item (only for INSERT operation and tables with autogenerated identity field) | string | Zero or one (OPTIONAL) |
Table 16 - Attributes of the "SubmitResponse" data type
This section specifies the operation behaviors.
Operation "ReadTableHeaders" enumerates tables accessible for the specified user and returns their headers in the specified localization language. The operation request is of type "ReadTableHeadersRequest" (see Table 11). The operation response is of type "ReadTableHeadersResponse" (see Table 12).
Operation "ReadTable" retrieves actions (access rights for specified user), header, fields (columns), items (rows) and references of the specified table. It automatically joins all the tables referenced by foreign keys from the specified table. The operation request is of type "ReadTableRequest" (see Table 13). The operation response is of type "ReadTableResponse" (see Table 14).
Operation "Submit" inserts, updates or deletes a single data item (table row) on the side of the operation provider. The operation request is of type "SubmitRequest" (see Table 15). The operation response is of type "SubmitResponse" (see Table 16).
This memo includes no request to IANA.
The communication security in the terms of RFC 3552 [RFC3552] is completely a matter of the communication environment (e.g. a transfer protocol). In order to ensure confidentiality across unsecured communication environment, the RSP messages SHOULD be encrypted. Furthermore, in unreliable communication environment, the data integrity SHOULD be verified. For these reasons, the HTTPS protocol is strongly RECOMMENDED as a transfer protocol for the RSP messages in the Internet environment.
The RSP protocol does not ensure full system security as specified in RFC 3552 [RFC3552]. It only provides a user access control in order to prevent the applications from unauthorized usage: in each operation request, the user credentials (user name and password or password hash) have to be provided by the operation requester.
The major threat regarding the system security represents inappropriate usage of the RSP-based applications, namely the SQL injection. Therefore, all the input data SHOULD be filtered on the side of the operation provider for the illegal characters and expressions depending upon the selected database engine.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. |
| [RFC3552] | Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, July 2003. |