Mosel Model Development Requirements

Review the following information to understand how to define the format by which input and result records will appear within Application Studio.

You should develop your Mosel model to get its input from a file named "input" located in the model's working directory. Should there be any results, the Mosel model will write them to a file named "result". Both the input and result files should be read and written using the 'helper' package named 'fssappstudio' which comes with FICO Xpress 7.8 (and later) versions.
The helper package reads and writes the input and results using an XML record format. The top-level element is InputRecordList (for inputs) or ResultRecordList (for results), which always contains a single InputRecord or ResultRecord. Scalars are represented as values enclosed in a named element, as shown in the following example:
```
<?xml version="1.0"?>
<InputRecordList xmlns="http://www.fico.com/input" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <InputRecord>
      <MyScalarValue>7.5</MyScalarValue>
   </InputRecord>
</InputRecordList>
```

Arrays are represented as a 'table' comprised of a named element which contains multiple 'rec' (_rec) elements that represent rows of the table. Each table row contains multiple elements representing individual cells. The following example has a table named 'Channels' with three columns: 'Channel', 'Cost', and 'Capacity'.

<?xml version="1.0"?>
 <InputRecordList xmlns="http://www.fico.com/input" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
   <InputRecord>
      <Channels>
      <Channels_rec>
        <Channel>1</Channel>
                  <Cost>0.5</Cost>
                  <Capacity>100</Capacity>
            </Channels_rec>
          <Channels_rec>
                  <Channel>2</Channel>
                  <Cost>1.2</Cost>
                  <Capacity>50</Capacity>
           </Channels_rec>       
          <Channels_rec>
               <Channel>3</Channel>
               <Cost>3</Cost>
               <Capacity>40</Capacity>
          </Channels_rec>
      </Channels>
     </InputRecord>
</InputRecordList>

Import this package by adding the following line to the top of your model:
```
uses "fssappstudio"
```
Add the following line to register the inputs:
```
appsxml_import("input")
```
If you have arrays named 'ChannelCost' and 'ChannelCapacity' that had a shared index set 'ChannelIDs', you could read them from the above XML example. To read an individual scalar value called 'MyScalarValue' into the variable 'myScalar', add the following lines:
```
initialisations from appsxml_in("MyScalarValue")
   myScalar as "[](MyScalarValue)"  
end-initialisations
```
Refer to the following code:
```
initialisations to appsxml_out("MyResultScalarValue")
     myScalar as "[](MyResultScalarValue)"
end-initialisations
initialisations to appsxml_out("ResultChannels")
   [ChannelCost,ChannelCapacity] as "[](ResultChannel,ResultCost,ResultCapacity)"
end-initialisations
appsxml_export("result")  
```
- The name in the brackets of appsxml_out refers to the 'table name', while the names in the "as' line refer to the 'column names'.
- The model results follow a similar format, except that it calls appsxml_out (rather than appsxml_in) and appsxml_export when all the data has been written, as shown in the preceding example.
- To test your model and run it locally, you will need to manually construct at least one input XML file. When running the model, two files are automatically created: input.xsd and result.xsd, which define the schemas of the input and result data-format respectively.

Note It is important that there be no overlap in the table or scalar names used in the input and result files.

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Mosel Model Development Requirements