Click here to view and discuss this page in DocCommentXchange. In the future, you will be sent there automatically.

SQL Anywhere 11.0.0 » SQL Anywhere Server - Programming » SQL Anywhere Data Access APIs » SQL Anywhere web services

 

Creating web services

Web services, created and stored in databases, define which URLs are valid and what they do. A single database can define multiple web services. It is possible to define web services in different databases so that they appear to be part of a single web site.

The following statements permit you to create, alter, and delete web services:

  • CREATE SERVICE
  • ALTER SERVICE
  • DROP SERVICE
  • COMMENT ON SERVICE

The general syntax of the CREATE SERVICE statement is as follows:

CREATE SERVICE service-name TYPE 'service-type' [ attributes ] [ AS statement ]
Service names

Since service names form part of the URL used to access them, they are flexible in terms of what characters they can contain. In addition to the standard alpha-numeric characters, the following characters are permitted: - _ . ! * '( )

In addition, service names other than those used in naming DISH services can contain a slash, "/", but some restrictions apply because this character is a standard URL delimiter and affects how SQL Anywhere interprets your URLs. It cannot be the first character of a service name. In addition, service names cannot contain two consecutive slashes.

The characters permitted in service names are also permitted in GROUP names, which apply to DISH services only.

Service types

The following service types are supported:

  • 'SOAP'   The result set is returned as a SOAP response. The format of the data is determined by the FORMAT clause. A request to a SOAP service must be a valid SOAP request, not just a simple HTTP request.

  • 'DISH'   A DISH service (Determine SOAP Handler) acts as a proxy for those SOAP services identified by the GROUP clause, and generates a WSDL (Web Services Description Language) document for each of these SOAP services.

  • 'HTML'   The result set of a statement or procedure is automatically formatted into an HTML document that contains a table.

  • 'XML'   The result set is returned as XML. If the result set is already XML, no additional formatting is applied. If it is not already XML, it is automatically formatted as XML. The effect is similar to that of using the FOR XML RAW clause in a SELECT statement.

  • 'JSON'   The result set is returned in JavaScript Object Notation (JSON). JSON is more compact than XML and has a similar structure. For more information about JSON, visit [external link] http://www.json.org.

  • 'RAW'   The result set is sent to the client without any further formatting. You can produce formatted documents by generating the required tags explicitly within your procedure.

Of all the service types, RAW gives you the most control over the output. However, it does require that you do more work as you must explicitly output all the necessary tags. The output of XML services can be adjusted by applying the FOR XML clause to the service's statement. The output of SOAP services can be adjusted using the FORMAT attribute of the CREATE or ALTER SERVICE statement.

For more information, see CREATE SERVICE statement.

Statements

The statement is the command, usually a stored procedure, that is called when someone accesses the service. If you define a statement, this is the only statement that can be run through this service. The statement is mandatory for SOAP services, and ignored for DISH services. The default is NULL, which means no statement.

You can create services that do not include statements. The statement is taken from the URL. Services configured in this way can be useful when you are testing a service, or want a general way of accessing information. To do so, either omit the statement entirely or use the phrase AS NULL in place of the statement.

Services without statements are a serious security risk because they permit web clients to execute arbitrary commands. When creating such services, you must enable authorization, which forces all clients to provide a valid user name and password. Even so, only services that define statements should be run in a production system.

Attributes

In general, all attributes are optional. However, some are interdependent. The following attributes are available:

  • AUTHORIZATION   This attribute controls which users can use the service. The default setting is ON. Authorization must be ON if no statement is provided. In addition, the authorization setting affects how user names, defined by the USER attribute, are interpreted.

  • SECURE   When set to ON, only secure connections are permitted. All connections received on the HTTP port are automatically redirected to the HTTPS port. The default is OFF, which enables both HTTP and HTTPS requests, provided these ports are enabled using the appropriate options when the database server is started.

    For more information, see -xs server option.

  • USER   The USER clause controls which database user accounts can be used to process service requests. However, the interpretation of this setting depends on whether authorization is ON or OFF.

    When authorization is set to ON, all clients must provide a valid user name and password when they connect. When authorization is ON, the USER option can be NULL, a database user name, or the name of a database group. If it is NULL, any database user can connect and make requests. Requests are run using the account and permissions of that user. If a group name is specified, only those users who belong to the group can run requests. All other database users are denied permission to use the service.

    If authorization is OFF, a statement must be provided. In addition, a user name must be provided. All requests are run using that user's account and permissions. Thus, if the server is connected to a public network, the permissions of the named user account should be minimal to limit the damage that could be caused through malicious use.

  • GROUP   The GROUP clause, which applies to DISH services only, determines which SOAP services are exposed by the DISH service. Only SOAP services whose names begin with the name of the group name of a DISH service are exposed by that DISH service. Thus, the group name is a common prefix among the exposed SOAP services. For example, specifying GROUP xyz exposes only SOAP services xyz/aaaa, xyz/bbbb, or xyz/cccc, but does not expose abc/aaaa or xyzaaaa. If no group name is specified, the DISH service exposes all the SOAP services in the database. The same characters are permitted in group names as in service names.

    SOAP services can be exposed by more than one DISH service. In particular, this feature permits a single SOAP service to supply data in multiple formats. The service type, unless specified in a SOAP service, is inherited from the DISH service. Thus, you can create a SOAP service that declares no format type, then include it in multiple DISH services, each of which specifies a different format.

  • FORMAT   The FORMAT clause, which applies to DISH and SOAP services only, controls the output format of the SOAP or DISH response. Output formats compatible with various types of SOAP clients, such as .NET or JAX-WS, are available. If the format of a SOAP service is not specified, the format is inherited from the service's DISH service declaration. If the DISH service also does not declare a format, it defaults to DNET, which is compatible with .NET clients. A SOAP service that does not declare a format can be used with different types of SOAP clients by defining multiple DISH services, each having a different FORMAT type.

  • URL [PATH]   The URL or URL PATH clause controls the interpretation of URLs and applies to XML, HTML, and RAW service types only. In particular, it determines whether URL paths are accepted and, if so, how they are processed. If the service name ends with the character "/", URL must be set to OFF.

    For more information, see CREATE SERVICE statement.