science

Information Object Class (ASN.1)

Information Object Class (ASN.1) is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Information Object Class (ASN.1) rather than just read about it. In short: ASN.1 Information Object Class is a concept widely used in ASN.1 specifications to address issues related to protocol specification similar to issues addressed by CORBA/IDL specifications. Information Object Classes are used for example to specify ROSE (Remote Operations Service Element) protocol in ASN.1.

Key takeaways

Information Object Class (ASN.1) belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Information Object Class (ASN.1) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Information Object Class (ASN.1) from memory before moving on to harder problems.

Reference excerpt

ASN.1 Information Object Class is a concept widely used in ASN.1 specifications to address issues related to protocol specification similar to issues addressed by CORBA/IDL specifications. Information Object Classes are used for example to specify ROSE (Remote Operations Service Element) protocol in ASN.1.

Abbreviations Abbreviations used throughout this article:

ASN.1 Abstract Syntax Notation One IOC Information Object Class IOS Information Object Set IO Information Object SQL Structured Query Language PER Packed Encoding Rules BER Basic Encoding Rules IDL Interface Definition Language CORBA Common Object Request Broker Architecture IIOP Internet Inter-ORB Protocol

Introduction The simplest way of thinking of ASN.1 Information Object Classes is to regard them as a way to represent IDL specification in ASN.1 using concepts derived from the relational databases theory and SQL syntax in particular. The concepts used in ASN.1 are more flexible than the ones used in IDL, because, continuing the analogy, they allow to "customize grammar" of the "IDL specification". ASN.1 encoding rules are used as a transfer syntax for remote invocations that resemble CORBA/IIOP. In the light of this comparison, we can draw an approximate analogy between concepts used in Information Object Classes and SQL and IDL concepts as shown in Table 1.

Analogy by example Table 2 illustrates by example correspondence of ASN.1 concepts to similar constructs found in SQL and IDL.

Parameterization If you carefully examine the ASN.1 example presented in Table 2 and compare it to IDL concepts, you will see one important limitation on the ASN.1 side. Our example ASN.1 data types which we agreed to compare to a high-level CORBA/IDL transfer syntax specification are limited to definition of such transfer syntax only for a single instance of what we compared to an IDL interface (Information Object Set in ASN.1 terms). In other words, such transfer syntax is not generic and it is not reusable. With the current set of known tools you can't define such a transfer syntax in a generic way in, say, ASN.1 specification A and then reuse it in ASN.1 specifications B and C that define concrete application-specific "IDL interfaces" on which A does not depend. The reason for the current limitation is that we currently hard-code our Information Object Set (MyWarehouseOps in case of OPERATION, or MyErrorSet in case of ERROR) into our ASN.1 data types (high-level transfer syntax specification). Now we need to make one last step to have a complete and fully functioning system. We need to introduce a concept of type parameterization using Information Object Set as a type formal parameter. Here is our Request type rewritten with the concept of parameterization in mind:

Now the high-level transfer syntax descriptor Request can be parameterized with any arbitrary Information Object Set ("IDL interface") conforming to the Information Object Class specification ("IDL grammar"). Therefore, we can now instantiate it for any Information Object Set as follows:

The WITH SYNTAX clause The WITH SYNTAX clause is effectively a tiny grammar language used to express ways of syntactic definitions of Information Objects. Consider the following example:

Enclosure in square brackets ([]) means optionality of syntactic constructs contained in []. Optionality can be nested. Tokens all in capital mean keywords, tokens starting with & mean productions requiring substitution of the corresponding entity in place of the token (ASN.1 value, type, or Information Object Set, either instance or reference thereof), depending on the Information Object Class to which this field refers. Now what we would have otherwise been written as:

in the presence of the WITH SYNTAX clause can be rewritten as follows:

To fully understand the grammar concept behind the WITH SYNTAX clause, imagine we wrote our OPERATION Information Object Class definition as follows:

Then a corresponding Information Object instance for the definition above is to be defined as follows:

References

Footnotes

General This article uses material from the OpenTTCN Wiki Archived 2008-11-21 at the Wayback Machine article "Information Object Classes (ASN.1)" licensed under the GNU Free Documentation License.

External links ITU-T RECOMMENDATION X.681, Abstract Syntax Notation One (ASN.1): Information object specification ASN.1 Made Simple — Advanced Topics from OSS Nokalva

Worked examples

Example 1 — a first encounter with Information Object Class (ASN.1)

Start with the simplest possible case. Write down what Information Object Class (ASN.1) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Information Object Class (ASN.1) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Information Object Class (ASN.1) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Information Object Class (ASN.1)

In research: Information Object Class (ASN.1) appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Information Object Class (ASN.1) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Information Object Class (ASN.1) is common in secondary-school and first-year university syllabi. It links to neighbouring topics ASN.1, Data modeling languages, so understanding it makes those chapters shorter.
In everyday life: Look for Information Object Class (ASN.1) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Information Object Class (ASN.1) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Information Object Class (ASN.1) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Information Object Class (ASN.1) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Information Object Class (ASN.1) in simple terms?

Why does Information Object Class (ASN.1) matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Information Object Class (ASN.1)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Information Object Class (ASN.1).