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Special Paclet Formats

Mathematica uses a number of specially constructed paclets to drive some of its frameworks. We'll briefly talk about these frameworks and how they showcase what paclets can do.

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Curated Data

The curated data framework has been in Mathematica since version 6. As I understand it, it is the Ur-usage for paclets. These paclets drive almost all the functions ending in Data , like ChemicalData , ElementData , and ExampleData .

A curated data function is in some sense a paclet is a divided into 3 chunks.

There is a code paclet that looks like:

 
 <DataType>Data 
  + PacletInfo.m 
  Kernel 
   + init.m 
  <DataType>Data.m

which configures a function <DataType>Data that acts as a router to two resource paclets.

The first resource paclet is looks like

 
 <DataType>Data_Index 
  + PacletInfo.m 
  Data 
   + Index.wdx 
   + Functions.wdx 
   + Names.wdx 
   + Groups.wdx 
   + Properties.wdx 
   + PrivateGroups.wdx

And the raw data distributes over a number of paclets that look like

 
 <DataType>Data_Part01 
  + PacletInfo.m 
  Data 
   + Part01.wdx

ExampleData

The ExampleData system works in a similar way to the bulk curated data, but since it provides more specialized resources it serves them in a slightly different way. Each of its resources looks like:

 
 ExampleData_<DataName>
 + PacletInfo.m 
  Data 
   + <DataName>.wdx

You can leverage this to make it serve your own resources with a bit of work.

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Service Connections

The Service Connections Framework is a good example of the flexibility of the paclet system. It provides a general set of high-level functions ServiceConnect , ServiceExecute , ServiceDisconnect , and low-level infrastructure that allow paclets to provide flexible connections to APIs with little effort.

Every service in the $Services list provides a paclet which looks like:

 
 ServiceConnection_<ServiceName>
 + PacletInfo.m 
  Kernel 
   + load.m 
   + <ServiceName>.m 
   + <ServiceName>Load.m 
   + <ServiceName>Functions.m

The framework first calls load.m which then loads the other packages. In the end a single set of functions is returned that encapsulates all the API parameters that the service provides.