Extended Document


While documents provide us with a dynamic schema, they force us to give up Java’s type-safety for working with type less key-value pairs. GigaSpaces supports extending the SpaceDocument class to provide a type-safe wrapper for documents which is much easier to code with, while maintaining the dynamic schema.

Definition

Let’s create a type-safe document wrapper for the Product type described in the Document Support page. The extensions are:

  • Provide a parameter less constructor, since the type name is fixed.
  • Provide type-safe properties, but instead of using private fields to store/retrieve the values, use the getProperty/setProperty methods from the SpaceDocument class.

Here’s an example (only parts of the properties have been implemented to keep the example short):

public class ProductDocument extends SpaceDocument {
    private static final String TYPE_NAME = "Product";
    private static final String PROPERTY_CATALOG_NUMBER = "CatalogNumber";
    private static final String PROPERTY_NAME = "Name";
    private static final String PROPERTY_PRICE = "Price";

    public ProductDocument() {
        super(TYPE_NAME);
    }

    public String getCatalogNumber() {
        return super.getProperty(PROPERTY_CATALOG_NUMBER);
    }
    public ProductDocument setCatalogNumber(String catalogNumber) {
        super.setProperty(PROPERTY_CATALOG_NUMBER, catalogNumber);
        return this;
    }

    public String getName() {
        return super.getProperty(PROPERTY_NAME);
    }
    public ProductDocument setName(String name) {
        super.setProperty(PROPERTY_NAME, name);
        return this;
    }

    public float getPrice() {
        return super.getProperty(PROPERTY_PRICE);
    }
    public ProductDocument setPrice(float price) {
        super.setProperty(PROPERTY_PRICE, price);
        return this;
    }
}

Registration

If your only intention is to write/update document entries, creating the extension class is sufficient - from the space’s perspective it is equivalent to a SpaceDocument instance. However, if you attempt to read/take entries from the space, the results will be SpaceDocument instances, and the cast to ProductDocument will throw an exception. To overcome that, we need to include the document wrapper class in the type introduction:

public void registerProductType(GigaSpace gigaspace) {
    // Create type descriptor:
    SpaceTypeDescriptor typeDescriptor =
        new SpaceTypeDescriptorBuilder("Product")
        // ... Other type settings
        .documentWrapperClass(ProductDocument.class)
        .create();
    // Register type:
    gigaspace.getTypeManager().registerTypeDescriptor(typeDescriptor);
}

This wrapper type-registration is kept in the proxy and not propagated to the server, so that from the server’s perspective this is still a virtual document type with no affiliated POJO class.

Usage

The following code snippet demonstrate usage of the ProductDocument extensions we’ve created to write and read documents from the space.

public void example(GigaSpace gigaSpace) {
    // Create a product document:
    ProductDocument product = new ProductDocument()
        .setCatalogNumber("hw-1234")
        .setName("Anvil")
        .setPrice(9.99f);
    // Write a product document:
    gigaSpace.write(product);

    // Read product document using a template:
    ProductDocument template = new ProductDocument()
        .setName("Anvil");
    ProductDocument result1 = gigaSpace.read(template);
    // Read product document using a SQL query:
    SQLQuery<ProductDocument> query = new SQLQuery<ProductDocument>("Product", "Price > ?")
        .setParameter(1, 5.5f);
    ProductDocument result2 = gigaSpace.read(query);
    // Read product document by ID:
    ProductDocument result3 = gigaSpace.readById(new IdQuery<ProductDocument>("Product", "hw-1234"));
}

Inheritance Support

SpaceDocument query supports inheritance relationships so that entries of a sub-class are visible in the context of the super class, but not the other way around. For example, suppose class EmployeeDoc extends class PersonDoc and PersonDoc extends from SpaceDocument, you can register the the sub classes in the following way:

SpaceTypeDescriptor employeeDescriptor = new SpaceTypeDescriptorBuilder(
				"Subclass Document Type Name", parentSpaceTypeDescriptor).create();

Here is an example:

public class PersonDoc extends SpaceDocument {

    public static final String TYPE_ID = "ID";
    public static final String TYPE_NAME = "PersonDoc";
    public static final String FIRST_NAME = "FirstName";
    public static final String LAST_NAME = "LastName";

    public PersonDoc() {
        super(TYPE_NAME);
    }

    public PersonDoc(String type) {
        super(type);
    }
    public void setId(String id) {
        super.setProperty(TYPE_ID, id);
    }

    public String getId() {
        return super.getProperty(TYPE_ID);
    }

    public String getFirstName() {
        return super.getProperty(FIRST_NAME);
    }

    public String getLastName() {
        return super.getProperty(FIRST_NAME);
    }

    public void setFirstNme(String name) {
        super.setProperty(FIRST_NAME, name);
    }

    public void setLastNme(String name) {
        super.setProperty(LAST_NAME, name);
    }
}
public class EmployeeDoc extends PersonDoc {

    public static final String TYPE_NAME = "EmployeeDoc";
    public static final String EMPLOYE_NUMBER = "EMPLOYE_NUMBER";

    public EmployeeDoc() {
        super(TYPE_NAME);
    }

    public String getEmployeNumber() {
        return super.getProperty(EMPLOYE_NUMBER);
    }

    public void setEmployeNumber(String number)
    {
        super.setProperty(EMPLOYE_NUMBER, number);
    }
}
   static public void registerDocument(GigaSpace space) {
        SpaceTypeDescriptor personDescriptor = new SpaceTypeDescriptorBuilder(
                PersonDoc.TYPE_NAME).documentWrapperClass(PersonDoc.class).
                idProperty(PersonDoc.TYPE_ID).create();
        // Register type:
        space.getTypeManager().registerTypeDescriptor(personDescriptor);

        SpaceTypeDescriptor employeeDescriptor = new SpaceTypeDescriptorBuilder(
                EmployeeDoc.TYPE_NAME, personDescriptor).documentWrapperClass(EmployeeDoc.class).create();
        // Register type:
        space.getTypeManager().registerTypeDescriptor(employeeDescriptor);
    }
public static void main(String[] args) {

        // Create the Space
        GigaSpace space = new GigaSpaceConfigurer(new EmbeddedSpaceConfigurer(
                "mySpace")).gigaSpace();


        registerDocument(space);

        PersonDoc doc1 = new PersonDoc();
        doc1.setId("1");
        doc1.setFirstNme("John");
        doc1.setLastNme("Fellner");

        space.write(doc1);

        EmployeeDoc doc2 = new EmployeeDoc();
        doc2.setId("2");
        doc2.setFirstNme("John");
        doc2.setLastNme("Fellner");
        doc2.setEmployeNumber("1234");

        space.write(doc2);

        SQLQuery<SpaceDocument> query1 = new SQLQuery<SpaceDocument>(
                PersonDoc.TYPE_NAME, "");

        PersonDoc[] result = (PersonDoc[]) space.readMultiple(query1);

        // You should see two objects
        System.out.println(result.length);

        SQLQuery<SpaceDocument> query2 = new SQLQuery<SpaceDocument>(
                EmployeeDoc.TYPE_NAME, "");

        EmployeeDoc[] result2 = (EmployeeDoc[]) space.readMultiple(query2);

        // You should see one object
        System.out.println(result2.length);
}