Home > Articles > Software Development & Management

  • Print
  • + Share This
This chapter is from the book

Remote Procedure Invocation

remoteprocedure_icon.gif

by Martin Fowler

An enterprise has multiple applications that are being built independently, with different languages and platforms. The enterprise needs to share data and processes in a responsive way.

How can I integrate multiple applications so that they work together and can exchange information?

How can I integrate multiple applications so that they work together and can exchange information?

File Transfer and Shared Database enable applications to share their data, which is an important part of application integration, but just sharing data is often not enough. Changes in data often require actions to be taken across different applications. For example, changing an address may be a simple change in data, or it may trigger registration and legal processes to take into account different rules in different legal jurisdictions. Having one application invoke such processes directly in others would require applications to know far too much about the internals of other applications.

This problem mirrors a classic dilemma in application design. One of the most powerful structuring mechanisms in application design is encapsulation, where modules hide their data through a function call interface. In this way, they can intercept changes in data to carry out the various actions they need to perform when the data is changed. Shared Database provides a large, unencapsulated data structure, which makes it much harder to do this. File Transfer allows an application to react to changes as it processes the file, but the process is delayed.

The fact that Shared Database has unencapsulated data also makes it more difficult to maintain a family of integrated applications. Many changes in any application can trigger a change in the database, and database changes have a considerable ripple effect through every application. As a result, organizations that use Shared Database are often very reluctant to change the database, which means that the application development work is much less responsive to the changing needs of the business.

What is needed is a mechanism for one application to invoke a function in another application, passing the data that needs to be shared and invoking the function that tells the receiver application how to process the data.

Develop each application as a large-scale object or component with encapsulated data. Provide an interface to allow other applications to interact with the running application.

02inf03.gif

Develop each application as a large-scale object or component with encapsulated data. Provide an interface to allow other applications to interact with the running application.

02inf03.gif

Remote Procedure Invocation applies the principle of encapsulation to integrating applications. If an application needs some information that is owned by another application, it asks that application directly. If one application needs to modify the data of another, it does so by making a call to the other application. This allows each application to maintain the integrity of the data it owns. Furthermore, each application can alter the format of its internal data without affecting every other application.

A number of technologies, such as CORBA, COM, .NET Remoting, and Java RMI, implement Remote Procedure Invocation (also referred to as Remote Procedure Call, or RPC). These approaches vary as to how many systems support them and their ease of use. Often these environments add additional capabilities, such as transactions. For sheer ubiquity, the current favorite is Web services, using standards such as SOAP and XML. A particularly valuable feature of Web services is that they work easily with HTTP, which is easy to get through firewalls.

The fact that there are methods that wrap the data makes it easier to deal with semantic dissonance. Applications can provide multiple interfaces to the same data, allowing some clients to see one style and others a different style. Even updates can use multiple interfaces. This provides a lot more ability to support multiple points of view than can be achieved by relational views. However, it is awkward for integrators to add transformation components, so each application has to negotiate its interface with its neighbors.

Since software developers are used to procedure calls, Remote Procedure Invocation fits in nicely with what they are already used to. Actually, this is more of a disadvantage than an advantage. There are big differences in performance and reliability between remote and local procedure calls. If people don't understand these, then Remote Procedure Invocation can lead to slow and unreliable systems (see [Waldo], [EAA]).

Although encapsulation helps reduce the coupling of the applications by eliminating a large shared data structure, the applications are still fairly tightly coupled together. The remote calls that each system supports tend to tie the different systems into a growing knot. In particular, sequencing—doing certain things in a particular order—can make it difficult to change systems independently. These types of problems often arise because issues that aren't significant within a single application become so when integrating applications. People often design the integration the way they would design a single application, unaware that the rules of the engagement change dramatically.

To integrate applications in a more loosely coupled, asynchronous fashion, use Messaging to enable frequent exchanges of small amounts of data, ones that are perhaps used to invoke remote functionality.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020