See:
Creating Named Shared Memory
http://msdn.microsoft.com/
...and
Using Shared Memory in a Dynamic-Link Library
http://msdn.microsoft.com/
for
Main Topics
Browse All Topics
Loading Advertisement...
Question
VirtualAlloxEx ReadProcessMemory WriteProcessMemory
Process1 reads data to memory and places pointers on a list and remains open
Process 2 needs to access the data from process 1.
Is it possible to save the pointers only of data in a process so the next process can access the data without re-reading the data into a buffer? I dont want to re-read the data in memory of process1 back into memory again in process2 as that defeats the object, I just want access.
I had a great post answered yesterday from subn0wa
http://www.experts-exchang
but Im stuck again on whether the above can be done?
If it can could someone provide me with an example? Thanks
This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.
Subscribe now for full access to Experts Exchange and get
Instant Access to this Solution
- Plus...
- 30 Day FREE access, no risk, no obligation
- Collaborate with the world's top tech experts
- Unlimited access to our exclusive solution database
- Never be left without tech help again
Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.
- "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
- "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
- "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.
See what Experts Exchange can do for you.
Got a question?
We've got the answer.
Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.
Need individual assistance?
Our experts are ready to help.
If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.
Want to learn from the best?
Read articles from industry experts.
Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.
Working on a long term project?
Store your work and research.
Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.
Access the answers to your technology questions today.
30-day free trial. Register in 60 seconds.
What Makes Experts Exchange Unique?
Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.
Trusted by the world's most respected brands.
Faithfully serving IT professionals since 1996.
Try it out and discover for yourself.
30-day free trial. Register in 60 seconds.
Free Tech Articles
-
WARNING: 5 Reasons why you should NEVER fix a computer for free.
It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
-
SCCM OSD Basic troubleshooting
SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
-
Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
-
Create a Win7 Gadget
This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
-
Outlook continually prompting for username and password
There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
-
Backup Exchange 2010 Information Store using Windows Backup
There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...
Cloud Class Webinars
- Avoiding Bugs in Microsoft Access
Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
- Top 10 Best New Features in Visio 2010
Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
- IT Consultant Business Secrets Revealed
Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
- Disaster Recovery and Business Continuity
Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
- Organize Your Visio Diagrams with Containers and Lists
Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
- How to Us Objects, Properties, Events and Methods in Microsoft Access
Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...
Join the Community
Give a Little. Get a Lot.
Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.
Answers
ReadProcessMemory/WritePro
You can't just take a pointer from another process and treat it as mapped into your own memory. You need to setup a shared memory segment.
To do that, you either use native Windows shared memory calls or a third-party framework, tool, or library. And you attach to the shared memory.
e.g.
SharedMemoryLib:
http://www.inf.pucrs.br/~p
Microsoft Article on shared memory
http://msdn.microsoft.com/
the boost library:
http://www.mathematik.uni-
http://www.boost.org/doc/l
http://www.codeproject.com
Thanks all. Mysidia, those are great links Ive speedread so I can make a post but will absorb the detail over this week, I see some very credible options, I didnt know the NAME of what it was I was trying to look for, its always the way I suppose, so its called shared memory, thank you.
What Im attempting to do is read my data to memory on a head node of a computer clustrer and have each instance of the data crunching client app "see the data" and act upon it accordingly. Im wondering whether shared memory can be seen across servers? Is this possible, I want the sub-nodes(the other servers) to have access to the shared memory, is that possible?
Also the first link you sent was very simple which is great, it shares arrays and my data is in arrays which is cool. my arrays end up being pointers in a list and there are a few lists on a list of lists if that makes sense so theres an overall pointer that just accesses the data in memory, is there a way of remembering this structure so that I only call the pointer from shared memory?
As I say Ill absorb the links in more detail, Ive upped teh points as well as I ve asked a couple of side questions, thanks for your support.
This is a place where one would normally use a RDBM like Oracle or postgresql for typical application loads, or sockets, to exchange state info between apps.
How to actually go about this actuallly depends on your needs ands the hardware you will choose; whether you just have a bunch of standalone PCs running normal OSes, or if you actually have specialized clustering hardware and/or software.
The better performance you need, the hardware the work will be.
Specialized multi-processing environments hardware/software may actually provide you shared memory facilities, e.g. Kerrighed, OpenSSI, Treadmarks, DIPC.
The feature is called DSM or "Distributed Shared Memory"; there are many ways you can accomplish memory sharing, from true DSM, to something like a shared file on a server and memcache for speeding reads of infrequently written data, but they all involve a fair deal of work.
Implementing a Shared Memory Cluster across multiple independent computers is quite a bit harder than implementing shared memory on one machine.
You'll have to deal with issues like concurrency between your apps; there will be issues if two apps try to write to the same place at once, and you don't have some mechanisms to ensure adequate read-write consistency, typical threading issues, except, now your lock status has to be persistent across different machines, and surprising issues may show up, e.g. application on another machine crashes, but leaves a record locked...
And ..what happens if your storage server reboots/crashes on you?
Locking issues can be trickier. With a shared FS, you might go for SCSI-3
reservations, however.
For apps with high performance requirements, NFS (indeed), or a SAN with a clustered filesystem may be your easiest options. mmap()'ing a file into memory, means the memory addresses will correspond to bytes in the file.
Fastest/robust would probably be to have specialized distributed filesystems
here ala the Google File system (which is unfortunately proprietary and
not available), and use sockets for most communication...
This all depends on the scale of your app and its requirements.
A NFS server is great if you don't mind single points of failure.
You might need a more complex architecture though, for a HA cluster.
3 Ways to Join
Business Accounts
- Perfect for organizations
- Multiple users
- Save over 36%
- Create a Business Account
Answer for Membership
- Earn free access
- Showcase your knowledge
- No credit card required
- Sign Up to Answer
Loading Advertisement...
by: DanRollinsPosted on 2009-05-09 at 16:34:28ID: 24346158
Any pointer into that memory would be meaningless/useless to an external process. For instance, if the external process wanted to pass a string from the shared memory to an API function, it would need to copy it to its own address space first -- so that it could pass a process-valid address to the API function.
As to access of the data... for instance, if you need a integer at offset 0x00001234 in the shared memory block, you need to copy it to a variable, anyway.
Shared memory blocks in a DLL can be accessed by all processes that use that same DLL. I don't know if that buys you anything -- the DLL would need to provide access to the data, which (again) would appear to defeat the purpose -- at some point the data needs to be copied to the local process, doesn't it?
If you describe your needs in more detail (i.e., what will you do with the shared memory block data) then I might be able to provide some additional ideas.