SOAP and DISH web services are the means by which you create standard SOAP web services that can be accessed by standard SOAP clients, such as those written with Microsoft .NET or JAX-WS.

SOAP services

SOAP services are the mechanism for constructing web services in SQL Anywhere that accept and process standard SOAP requests.

To declare a SOAP service, specify that the service is to be of type SOAP. The body of a standard SOAP request is SOAP envelope, meaning an XML document with a specific format. SQL Anywhere parses and processes these requests using the procedures you provide. The response is automatically formatted in the form of a standard SOAP response, which is also a SOAP envelope, and returned to the client.

The syntax of the statement used to create SOAP services is as follows:

CREATE SERVICE service-name
TYPE 'SOAP'
[ FORMAT { 'DNET' | 'CONCRETE' | 'XML' | NULL } ]
[ common-attributes ]
AS statement

DISH services

DISH services act as proxies for groups of SOAP services. In addition, they automatically construct WSDL (Web Services Description Language) documents for their clients that describe the SOAP services that they currently expose.

When you create a DISH service, the name given in the GROUP clause determines which SOAP services the DISH service exposes. Every SOAP service whose name is prefixed with the name of the DISH service is exposed. For example, specifying GROUP xyz exposes SOAP services xyz/aaaa, xyz/bbbb, or xyz/cccc. It does not expose SOAP services named abc/aaaa or xyzaaaa. SOAP services can be exposed by more than one DISH service. If no group name is specified, the DISH service exposes all the SOAP services in the database. The same characters are permitted in DISH group names as in SOAP service names.

The syntax of the statement used to create DISH services is as follows:

CREATE SERVICE service-name
TYPE 'DISH'
[ GROUP { group-name | NULL } ]
[ FORMAT { 'DNET' | 'CONCRETE' | 'XML' | NULL } ]
[ common-attributes ]

SOAP and DISH service formats

The FORMAT clause of the CREATE SERVICE statement customizes the SOAP service data payload to best suit the various types of SOAP clients, such as .NET and JAX-WS. The FORMAT clause affects the content of the WSDL document returned by a DISH service and the format of data payloads returned in SOAP responses.

The default format, DNET, is a native format for use with .NET SOAP client applications, which expect a .NET DataSet format.

The CONCRETE format is for use with clients such as JAX-WS and .NET that automatically generate interfaces based on the format of the returned data structures. When you specify this format, the WSDL document returned by SQL Anywhere exposes a SimpleDataset element that describes a result set in concrete terms. This element is a containment hierarchy of a rowset composed of an array of rows, each containing an array of column elements.

The XML format is for use with SOAP clients that accept the SOAP response as one large string, and use an XML parser to locate and extract the required elements and values. This format is generally the most portable between different types of SOAP clients.

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.

Creating homogeneous DISH services

SOAP services need not specify a format type—you can set the format type to NULL. In this case, the format is inherited from the DISH services that act as proxies for them. More than one DISH service can act as a proxy for each SOAP service, and these DISH services need not be of the same type. These facts mean that it is possible to use a single SOAP service with different types of SOAP clients, such as .NET and JAX-WS, by using multiple DISH services, each of a different type. Such DISH services are said to be homogeneous because they expose the same data payloads for the same SOAP services, but in different formats.

For example, consider the following two SOAP services, neither of which specifies a format:

CREATE SERVICE "abc/hello"
TYPE 'SOAP'
AS CALL hello(:student);

CREATE SERVICE "abc/goodbye"
TYPE 'SOAP'
AS CALL goodbye(:student);

Since neither of these services includes a FORMAT clause, the format, by default, is NULL. It is thus inherited from the DISH service that is acting as a proxy. Now, consider the following two DISH services:

CREATE SERVICE "abc_xml"
TYPE 'DISH'
GROUP "abc"
FORMAT 'XML';

CREATE SERVICE "abc_concrete"
TYPE 'DISH'
GROUP "abc"
FORMAT 'CONCRETE';

Since both DISH services specify the same group name abc, they act as proxies for the same SOAP services, namely all SOAP services whose names have the prefix "abc/".

However, when either of the two SOAP services is accessed through the abc_xml DISH service, the SOAP service inherits the XML format; when accessed through the abc_concrete SOAP service, the SOAP service inherits the CONCRETE format.

Homogeneous DISH services provide a means of avoiding duplicate services whenever you want to give different types of SOAP clients access to the SOAP web services you create.