EJB Bad Practices: Use of Java I/O
Weakness ID: 576 (Weakness Variant)Status: Draft
+ Description

Description Summary

The program violates the Enterprise JavaBeans (EJB) specification by using the java.io package.

Extended Description

The Enterprise JavaBeans specification requires that every bean provider follow a set of programming guidelines designed to ensure that the bean will be portable and behave consistently in any EJB container. In this case, the program violates the following EJB guideline: "An enterprise bean must not use the java.io package to attempt to access files and directories in the file system." The specification justifies this requirement in the following way: "The file system APIs are not well-suited for business components to access data. Business components should use a resource manager API, such as JDBC, to store data."

+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms

Languages

Java

+ Demonstrative Examples

Example 1

The following Java example is a simple stateless Enterprise JavaBean that retrieves the interest rate for the number of points for a mortgage. In this example, the interest rates for various points are retrieved from an XML document on the local file system, and the EJB uses the Java I/O API to retrieve the XML document from the local file system.

(Bad Code)
Example Language: Java 
@Stateless
public class InterestRateBean implements InterestRateRemote {

private Document interestRateXMLDocument = null;
private File interestRateFile = null;

public InterestRateBean() {
try {
/* get XML document from the local filesystem */
interestRateFile = new File(Constants.INTEREST_RATE_FILE);

if (interestRateFile.exists())
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
interestRateXMLDocument = db.parse(interestRateFile);
}
} catch (IOException ex) {...}
}

public BigDecimal getInterestRate(Integer points) {
return getInterestRateFromXML(points);
}

/* member function to retrieve interest rate from XML document on the local file system */
private BigDecimal getInterestRateFromXML(Integer points) {...}
}

This use of the Java I/O API within any kind of Enterprise JavaBean violates the EJB specification by using the java.io package for accessing files within the local filesystem.

An Enterprise JavaBean should use a resource manager API for storing and accessing data. In the following example, the private member function getInterestRateFromXMLParser uses an XML parser API to retrieve the interest rates.

(Good Code)
Example Language: Java 
@Stateless
public class InterestRateBean implements InterestRateRemote {

public InterestRateBean() {
}

public BigDecimal getInterestRate(Integer points) {
return getInterestRateFromXMLParser(points);
}

/* member function to retrieve interest rate from XML document using an XML parser API */
private BigDecimal getInterestRateFromXMLParser(Integer points) {...}
}
+ Potential Mitigations

Do not use Java I/O when writing EJBs.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness BaseWeakness Base695Use of Low-Level Functionality
Development Concepts (primary)699
Research Concepts (primary)1000
+ Content History
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential Mitigations, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Other Notes
2009-10-29CWE Content TeamMITREInternal
updated Description, Other Notes
2009-12-28CWE Content TeamMITREInternal
updated Demonstrative Examples
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