ZCFG : the ZOO Service Configuration File
The ZOO Service configuration file (.zcfg) describes the service and will be parsed by the ZOO Kernel to know how to handle it. We will describe here what such a file contains. You can also take a look at the existing examples of ZCFG file in the cgi-env directory of each services available on the ZOO-Project SVN source tree.
A ZOO Configuration file is divided in three distinct sections :
- Main metadata informations
- List of Inputs metadata informations
- List of Outputs metadata informations
The ZOO Service Configuration File is case sensitive.
Main metadata informations
The fist part in a ZOO Configuration contains the metadata informations relatives to the service. Note that the "name of your service", between bracket on the first line, have to be the exact same name as the function you defined in your services provider code. In most case, this name is also the name of the ZCFG file without the ".zcfg" extension.
You can see bellow a description of the main metadata informations:
List of Inputs
The list of inputs contains metadata information of each supported input and they are grouped using a <DataInputs> node.
Each input is defined as :
- a name (between brackets as for the name of the service before)
- various medata properties (Title, Abstract, minOccurs and maxOccurs)
- a Type Of Data node (description)
A typical list of inputs (<DataInputs>) look like the following:
Note that you can add <MetaData> node as in the main metadata information.
List of Outputs
The list of outputs is very similar to a list of inputs except it is designed as a <DataOutputs> node.
A typical <DataOutputs> node look like the following:
Type Of Data Nodes
From the begining of this ZCFG presentation, we spoke about "Type Of Data Nodes" to describe data type of inputs and outputs.
You can define your data as:
Except for LiteralData, each Type Of Data node have at least one <Default> and one <Supported> node. Even if one of those are empty, it has to be present as an opening and closing tag on two different line. So, something like the following:
In other case, ZOO-Kernel won't be able to parse your ZCFG and will fail to process requests.
A <LiteralData> node get one <Default>, zero or more <Supported> node depending on the existence or the number of supported Unity Of Mesures (UOM) and a dataType property. The dataType property define the type of literal data, a string, an interger and so on (consult the complete list of supported data types). <Default> and <Supported> nodes can get the uom property to define which UOM have to be used for this input value.
For input <LiteralData> nodes, you can add the value property to the <Default> node to define a default value for this input. This means that, when your Service will be run, even if the input wasn't defined, this default value will be set as the current value for this input.
A typical <LiteralData> node, defining a float data type using meters or degree UOM, look like the following:
A <BoundingBoxData> node contains one <Defautl> node getting a CRS property defining the default Coordinate Reference Systems (CRS) and one or more <Supported> nodes depending on the number of CRS your service support (note that you can also use a list of supported CRS separated them by coma in only one <Supported> node).
A ComplexData node get a <Default> and one or more <Supported> nodes depending on the number of supported format. A format is this set of properties : mimeType, encoding and optionaly schema.
For output ComplexData nodes, you can add the extension property to define what extension to use to name the file when storing the result is required. Obviously, you'll have to add the extension property to each supported format ( <Default> and <Supported> nodes). You can also add the asReference property to the <Default> node to define if the output should be stored on server side per default. Note, that the client can always modify this behavior by setting asReference attribute to true or false for this output in the request ResponseDocument parameter.
You can see above a sample ComplexData node for default application/json and text/xml (encoded in UTF-8 or base64) mimeTypes support: